Abstract:
Provided is a lens array that can reliably obtain monitor light and is easy to manufacture. In the provided lens array, light incident on a first lens surface ( 11 ) from light-emitting elements is split by a reflective/transmissive layer ( 17 ) between a first optical surface ( 14   a ) and a first prism surface ( 16   a ) and sent, respectively, towards a second lens surface ( 12 ) and a third lens surface ( 13 ). Monitor light included in the light sent towards the third lens surface ( 13 ) is sent by the third lens surface ( 13 ) towards a light-receiving element ( 8 ). The path of light incident on the first optical surface ( 14   a ) is collinear with the path of light outgoing from the second optical surface ( 14   b ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a lens array and an optical module provided therewith, and relates particularly to a lens array and an optical module provided therewith that are suitable for optically coupling light emitting elements and end faces of optical transmission members. 
       BACKGROUND ART 
       [0002]    In recent years, the so-called optical interconnection, a technique for transmitting signals within a system device, or between devices or between optical modules at high speed, has found a wide variety of applications. Here, the optical interconnection refers to a technique in which optical components are used as if they were electric components, and the components are mounted on a mother board or a circuit board for use in a personal computer, a vehicle, an optical transceiver or the like. 
         [0003]    Optical modules used for such optical interconnection have a variety of applications, such as intra-device and inter-device connection of components for internal connections of a media converter or a switching hub, an optical transceiver, medical equipment, a testing device, a video system, or a high speed computer cluster. 
         [0004]    In such types of optical modules, light that contains communication information emitted from a light emitting element is coupled via a lens to an end face of an optical fiber, which is an example of an optical transmission member, to transmit the communication information via the optical fiber. 
         [0005]    To support bidirectional communication, some optical modules include, together with a light emitting element, a light receiving element for receiving the light that contains communication information propagated through an optical fiber and emitted from an end face of the optical fiber. 
         [0006]    Conventionally, in such an optical module, variations in output characteristics of light from an light emitting element due to adverse effects of temperature may hinder appropriate transmission of communication information. 
         [0007]    Thus, in such types of optical modules, various techniques have been proposed for monitoring light (in particular, an intensity or amount of light) emitted from a light emitting element to stabilize output characteristics of the light emitting element. 
         [0008]    For instance, PTL 1 discloses an optical element that includes a reflecting surface (reflecting surface part) around a lens surface (transmitting surface part), the reflecting surface reflecting a part of light emitted from a light emitting element toward a light receiving element, as monitor light. 
         [0009]    Furthermore, PTL 2 discloses an optical unit that has an optical surface and includes a total reflecting mirror that totally reflects laser light emitted from a surface emitting laser toward an optical fiber side, and a groove that reflects a part of the laser light emitted from the surface emitting laser as monitor light toward a PD side, in a connecting manner. 
       CITATION LIST 
     Patent Literature 
     PTL 1 
       [0000]    
       
         Japanese Patent Application Laid-Open No. 2008-151894 
       
     
       PTL 2 
       [0000]    
       
         Japanese Patent Application Laid-Open No. 2006-344915 (in particular, see FIGS. 16A and 16B) 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0012]    Unfortunately, PTL 1 has a problem of difficulty against effective application in the case where multichannel optical communication is to be realized in a compact configuration. That is, in recent years, there has been an increasing demand for a lens array that includes lenses arranged in a predetermined alignment direction, as a small optical component for realizing multichannel optical communication. As to such type of lens array, in a light emitting device including light emitting elements arranged in line, the light emitting elements are disposed so as to be opposed to respective lens surfaces on an incident side of the lens array, and optical fibers are arranged so as to be opposed to respective lens surfaces on an emitting side of the lens array. Light emitted from each light emitting element is optically coupled to end faces of the optical fibers by the respective lenses of the lens array, thereby allowing multichannel optical communication (transmission). In such a lens array, it is very important to monitor the light emitted from the light emitting elements in terms of securing stability and reliability of optical communication. In such a lens array, each of the lenses is formed in a significantly reduced diameter, and furthermore, the lenses adjacent to each other are arranged at a significantly narrow pitch. Accordingly, there is a problem in that it is difficult to apply the configuration described in PTL 1 to a lens array to form a reflecting surface for reflecting monitor light, around the lenses. 
         [0013]    PTL 2 requires positional accuracy at the interface between the total reflecting mirror and the groove, which causes a problem of difficulty in manufacturing. 
         [0014]    It is an object of the present invention to provide a lens array and an optical module provided therewith that can securely acquire monitor light and realize facilitation of manufacturing. 
       Solution to Problem 
       [0015]    A lens array of the present invention adopts a configuration in which a lens array is disposed between an optoelectric converting device and an optical transmission member, the optoelectric converting device including a plurality of light emitting elements formed therein in line and at least one light receiving element formed therein for receiving monitor light, the monitor light being used for monitoring light emitted from at least one of the plurality of light emitting elements, the lens array being able to optically couple the plurality of light emitting elements with an end face of the optical transmission member, the lens array including: a plurality of first lens surfaces that are formed to align in a predetermined alignment direction corresponding to the plurality of light emitting elements on a first surface facing the optoelectric converting device in a lens array body, the first lens surfaces each receiving light that is emitted from each of the plurality of light emitting elements and incident on the first lens surfaces; a plurality of second lens surfaces for emitting light incident on each of the plurality of first lens surfaces from each of the plurality of light emitting elements toward the end face of the optical transmission member, the second lens surfaces being formed to align along the alignment direction of the first lens surfaces on a second surface facing the end face of the optical transmission member in the lens array body; at least one third lens surface for emitting the monitor light incident from an inside of the lens array body toward the light receiving element, the third lens surface being formed on the first surface of the lens array body; a concave part formed in the lens array body in a reentrant manner so that optical paths connecting the first lens surfaces and the second lens surfaces pass through in the concave part; a first optical surface that is formed as a part of an inner surface of the concave part and formed to have a predetermined inclining angle to the second surface, the first optical surface receiving, in an incident direction perpendicular to the second surface, the light that is emitted from each of the plurality of light emitting elements and incident on the first lens surfaces; a second optical surface that is a part of the inner surface of the concave part, formed as a portion opposed to the first optical surface and formed to be parallel to the second surface, the light from each of the plurality of light emitting elements having been incident on the first optical surface and subsequently moved forth toward the second lens surface side being perpendicularly incident on the second optical surface; a prism that is disposed in a space formed by the concave part, formed to have a refractive index identical to that of the lens array body, and forms an optical path of the light from each of the plurality of light emitting elements having been incident on the first optical surface and subsequently moved forth toward the second lens surface side; a first prism surface that forms a part of a surface of the prism and is disposed at a position adjacent to the first optical surface; a second prism surface that is a part of the surface of the prism, forms a portion opposed to the first prism surface, and is disposed parallel to the second optical surface at a position facing the second optical surface; a reflecting/transmitting layer for reflecting the light that is emitted from each of the plurality of light emitting elements and incident on the first optical surface at a predetermined reflectance toward the third lens surface side and allowing the light to pass through at a predetermined transmittance toward the prism side, while reflecting at least one beam of the light from the plurality of light emitting elements as the monitor light, the reflecting/transmitting layer intervening between the first optical surface and the first prism surface; and a filler that is inserted between the second optical surface and the second prism surface and has a predetermined refractive index. 
         [0016]    A lens array of the present invention adopts a configuration in which a lens array is disposed between an optoelectric converting device and an optical transmission member, the optoelectric converting device including a plurality of light emitting elements formed therein in line and at least one light receiving element formed therein for receiving monitor light, the monitor light being used for monitoring light emitted from at least one of the plurality of light emitting elements, the lens array being able to optically couple the plurality of light emitting elements with an end face of the optical transmission member, the lens array including: a plurality of first lens surfaces that are formed to align in a predetermined alignment direction corresponding to the plurality of light emitting elements on a first surface facing the optoelectric converting device in a lens array body, the first lens surfaces each receiving light that is emitted from each of the plurality of light emitting elements and incident on the first lens surfaces; a plurality of second lens surfaces for emitting light incident on each of the plurality of first lens surfaces from each of the plurality of light emitting elements toward the end face of the optical transmission member, the second lens surfaces being formed to align along the alignment direction of the first lens surfaces on a second surface facing the end face of the optical transmission member in the lens array body; at least one third lens surface for emitting the monitor light incident from an inside of the lens array body toward the light receiving element, the third lens surface being formed on the first surface of the lens array body; a concave part formed in the lens array body in a reentrant manner so that optical paths connecting the first lens surfaces and the second lens surfaces pass through in the concave part; a first optical surface that is formed as a part of an inner surface of the concave part and formed to be parallel to the second surface, the first optical surface receiving, in an incident direction perpendicular to the second surface, the light that is emitted from each of the plurality of light emitting elements and incident on the first lens surfaces; a second optical surface that is a part of the inner surface of the concave part, formed as a portion opposed to the first optical surface and formed to be parallel to the second surface, the light from each of the plurality of light emitting elements having been incident on the first optical surface and subsequently moved forth toward the second lens surface side being perpendicularly incident on the second optical surface; a prism that is disposed in a space formed by the concave part and forms an optical path of the light from each of the plurality of light emitting elements having been incident on the first optical surface and subsequently moved forth toward the second lens surface side; a first prism surface that forms a part of a surface of the prism and is disposed to have a predetermined inclining angle to the second surface at a position facing the first optical surface; a second prism surface that is a part of the surface of the prism, forms a portion opposed to the first prism surface, and is disposed parallel to the second surface at a position facing the second optical surface; a reflecting/transmitting layer for reflecting the light that is emitted from each of the plurality of light emitting elements and incident on the first optical surfaces at a predetermined reflectance toward the third lens surface side and allowing the light to pass through at a predetermined transmittance toward the prism side, while reflecting at least one beam of the light from the plurality of light emitting elements as the monitor light, the reflecting/transmitting layer being formed on the first prism surface; and a filler that is inserted between the first optical surface and the reflecting/transmitting layer, and has a refractive index identical to that of the prism. 
         [0017]    A lens array of the present invention adopts a configuration in which a lens array is disposed between an optoelectric converting device and an optical transmission member, the optoelectric converting device including a plurality of light emitting elements formed therein in line and at least one light receiving element formed therein for receiving monitor light, the monitor light being used for monitoring light emitted from at least one of the plurality of light emitting elements, the lens array being able to optically couple the plurality of light emitting elements with an end face of the optical transmission member, the lens array including: a plurality of first lens surfaces that are formed to align in a predetermined alignment direction corresponding to the plurality of light emitting elements on a first surface facing the optoelectric converting device in a lens array body, the first lens surfaces each receiving light that is emitted from each of the plurality of light emitting elements and incident on the first lens surfaces; a plurality of second lens surfaces for emitting light incident on each of the plurality of first lens surfaces from each of the plurality of light emitting elements toward the end face of the optical transmission member, the second lens surfaces being formed to align along the alignment direction of the first lens surfaces on a second surface facing the end face of the optical transmission member in the lens array body; at least one third lens surface for emitting the monitor light incident from an inside of the lens array body toward the light receiving element, the third lens surface being formed on the first surface of the lens array body; a concave part formed in the lens array body in a reentrant manner so that optical paths connecting the first lens surfaces and the second lens surfaces pass through in the concave part; a first optical surface that is formed as a part of an inner surface of the concave part and formed to be parallel to the second surface, the first optical surface receiving, in an incident direction perpendicular to the second surface, the light that is emitted from each of the plurality of light emitting elements and incident on the first lens surfaces; a second optical surface that is a part of the inner surface of the concave part, formed as a portion opposed to the first optical surface and formed to be parallel to the second surface, the light from each of the plurality of light emitting elements having been incident on the first optical surface and subsequently moved forth toward the second lens surface side being perpendicularly incident on the second optical surface; a prism that is disposed in a space formed by the concave part and forms an optical path of the light from each of the plurality of light emitting elements having been incident on the first optical surface and subsequently moved forth toward the second lens surface side; a first prism surface that forms a part of a surface of the prism and is disposed to have a predetermined inclining angle to the second surface at a position facing the first optical surface; a second prism surface that is a part of the surface of the prism, forms a portion opposed to the first prism surface, and is disposed to have a predetermined inclining angle to the second surface at a position facing the second optical surface; a reflecting/transmitting layer for reflecting the light that is emitted from each of the plurality of light emitting elements and incident on the first lens surfaces at a predetermined reflectance toward the third lens surface side and allowing the light to pass through at a predetermined transmittance toward the prism side, while reflecting at least one beam of the light from the plurality of light emitting elements as the monitor light, the reflecting/transmitting layer being formed on the first prism surface; and a filler that is inserted between the first optical surface and the reflecting/transmitting layer and between the second optical surface and the second prism surface, and has a refractive index identical to that of the prism. 
         [0018]    A lens array of the present invention adopts a configuration in which a lens array is disposed between an optoelectric converting device and an optical transmission member, the optoelectric converting device including a plurality of light emitting elements formed therein in line and at least one light receiving element formed therein for receiving monitor light, the monitor light being used for monitoring light emitted from at least one of the plurality of light emitting elements, the lens array being able to optically couple the plurality of light emitting elements with an end face of the optical transmission member, the lens array including: a plurality of first lens surfaces that are formed to align in a predetermined alignment direction corresponding to the plurality of light emitting elements on a first surface facing the optoelectric converting device in a lens array body, the first lens surfaces each receiving light that is emitted from each of the plurality of light emitting elements and incident on the first lens surfaces; a plurality of second lens surfaces for emitting light incident on each of the plurality of first lens surfaces from each of the plurality of light emitting elements toward the end face of the optical transmission member, the second lens surfaces being formed to be arranged in line along the alignment direction of the first lens surfaces on a second surface facing the end face of the optical transmission member in the lens array body; at least one third lens surface for emitting the monitor light incident from an inside of the lens array body toward the light receiving element, the third lens surface being formed on the first surface of the lens array body; a concave part formed in the lens array body in a reentrant manner so that optical paths connecting the first lens surfaces and the second lens surfaces pass through in the concave part; a first optical surface that is formed as a part of an inner surface of the concave part and formed to have a predetermined slight inclining angle to the second surface, the first optical surface receiving, in an incident direction perpendicular to the second surface, the light that is emitted from each of the plurality of light emitting elements and incident on the first lens surfaces; a second optical surface that is a part of the inner surface of the concave part, formed as a portion opposed to the first optical surface and formed to have a predetermined slight inclining angle to the second surface, the light from each of the plurality of light emitting elements having been incident on the first optical surface and subsequently moved forth toward the second lens surface side being incident on the second optical surface perpendicularly to the second surface; a prism that is disposed in a space formed by the concave part, formed to have a refractive index identical to that of the lens array body, and forms an optical path of the light from each of the plurality of light emitting elements having been incident on the first optical surface and subsequently moved forth toward the second lens surface side; a first prism surface that forms a part of a surface of the prism and is disposed to have a predetermined inclining angle to the second surface at a position facing the first optical surface; a second prism surface that is a part of the surface of the prism, forms a portion opposed to the first prism surface, and is disposed to have a predetermined inclining angle to the second surface at a position facing the second optical surface; a reflecting/transmitting layer for reflecting the light that is emitted from each of the plurality of light emitting elements and incident on the first lens surfaces at a predetermined reflectance toward the third lens surface side and allowing the light to pass through at a predetermined transmittance toward the prism side, while reflecting at least one beam of the light from the plurality of light emitting elements as the monitor light, the reflecting/transmitting layer being formed on the first prism surface; and a filler that is inserted between the first optical surface and the reflecting/transmitting layer and between the second optical surface and the second prism surface, and has a refractive index identical to that of the prism. 
         [0019]    An optical module of the present invention adopts a configuration including the aforementioned lens array, and an optoelectric converting device corresponding thereto. 
         [0020]    A lens array of the present invention adopts a configuration in which a lens array is disposed between an optoelectric converting device and an optical transmission member, the optoelectric converting device including a plurality of light emitting elements formed therein in line and at least one light receiving element formed therein for receiving monitor light, the monitor light being used for monitoring light emitted from at least one of the plurality of light emitting elements, the lens array being able to optically couple the plurality of light emitting elements with an end face of the optical transmission member, the lens array including: a plurality of first lens surfaces that are formed to align in a predetermined alignment direction corresponding to the plurality of light emitting elements on a first surface facing the optoelectric converting device in a lens array body, the first lens surfaces each receiving light that is emitted from each of the plurality of light emitting elements and incident on the first lens surfaces; a plurality of second lens surfaces for emitting light incident on each of the plurality of first lens surfaces from each of the plurality of light emitting elements toward the end face of the optical transmission member, the second lens surfaces being formed to align along the alignment direction of the first lens surfaces on a second surface facing the end face of the optical transmission member in the lens array body; at least one third lens surface for emitting the monitor light incident from an inside of the lens array body toward the light receiving element, the third lens surface being formed on the first surface of the lens array body; a concave part formed in the lens array body in a reentrant manner so that optical paths connecting the first lens surfaces and the second lens surfaces pass through in the concave part; a first optical surface that is formed as a part of an inner surface of the concave part and formed to have a predetermined inclining angle to the second surface, the first optical surface receiving, in an incident direction perpendicular to the second surface, the light that is emitted from each of the plurality of light emitting elements and incident on the first lens surfaces; a second optical surface that is a part of the inner surface of the concave part, formed as a portion opposed to the first optical surface and formed to be parallel to the second surface, the light from each of the plurality of light emitting elements having been incident on the first optical surface and subsequently moved forth toward the second lens surface side being perpendicularly incident on the second optical surface; a prism that is disposed in a space formed by the concave part, formed to have a refractive index identical to that of the lens array body, and forms an optical path of the light from each of the plurality of light emitting elements having been incident on the first optical surface and subsequently moved forth toward the second lens surface side; a first prism surface that forms a part of a surface of the prism and is disposed parallel to the first optical surface at a position facing the first optical surface; a second prism surface that is a part of the surface of the prism, forms a portion opposed to the first prism surface, and is disposed parallel to the second optical surface at a position facing the second optical surface; a reflecting/transmitting layer for reflecting the light that is emitted from each of the plurality of light emitting elements and incident on the first optical surfaces at a predetermined reflectance toward the third lens surface side and allowing the light to pass through at a predetermined transmittance toward the prism side, while reflecting at least one beam of the light from the plurality of light emitting elements as the monitor light, the reflecting/transmitting layer being disposed on the first prism surface or the first optical surface; an adhesive sheet that is disposed between the reflecting/transmitting layer on the first prism surface and the first optical surface or between the first prism surface and the reflecting/transmitting layer on the first optical surface, and has a predetermined refractive index for bonding the prism on the lens array body; and a filler that is inserted between the second optical surface and the second prism surface and has a predetermined refractive index. 
         [0021]    An optical module of the present invention adopts a configuration including the aforementioned lens array, and the aforementioned optoelectric converting device corresponding thereto. 
         [0022]    A lens array of the present invention adopts a configuration in which a lens array is disposed between an optoelectric converting device and an optical transmission member, the optoelectric converting device including a plurality of light emitting elements formed therein in line and at least one first light receiving element formed therein for receiving monitor light, the monitor light being used for monitoring light emitted from at least one of the plurality of light emitting elements, the lens array being able to optically couple the plurality of light emitting elements with an end face of the optical transmission member, the lens array including: a plurality of first lens surfaces that are formed to align in a predetermined alignment direction corresponding to the plurality of light emitting elements on a first surface facing the optoelectric converting device in a lens array body, the first lens surfaces each receiving light that is emitted from each of the plurality of light emitting elements and incident on the first lens surfaces; a plurality of second lens surfaces for emitting light incident on each of the plurality of first lens surfaces from each of the plurality of light emitting elements toward the end face of the optical transmission member, the second lens surfaces being formed to align along the alignment direction of the first lens surfaces on a second surface facing the end face of the optical transmission member in the lens array body; at least one third lens surface for emitting the monitor light incident from an inside of the lens array body toward the first light receiving element, the third lens surface being formed on the first surface of the lens array body; a concave part formed in the lens array body in a reentrant manner so that optical paths connecting the first lens surfaces and the second lens surfaces pass through in the concave part; a first optical surface that is formed as a part of an inner surface of the concave part and formed to have a predetermined inclining angle to the second surface, the first optical surface receiving, in an incident direction perpendicular to the second surface, the light that is emitted from each of the plurality of light emitting elements and incident on the first lens surfaces; a second optical surface that is a part of the inner surface of the concave part, formed as a portion opposed to the first optical surface and formed to have a predetermined inclining angle to the second surface, the light from each of the plurality of light emitting elements having been incident on the first optical surface and subsequently moved forth toward the second lens surface side being incident on the second optical surface; a first reflecting/transmitting layer for reflecting the light that is emitted from each of the plurality of light emitting elements and incident on the first optical surfaces at a predetermined reflectance toward the third lens surface side and allowing the light to pass through at a predetermined transmittance toward the second optical surface side, while reflecting at least one beam of the light from the plurality of light emitting elements as the monitor light, the reflecting/transmitting layer being disposed on the first optical surface or adjacent thereto; and a filler that fills a space formed by the concave part and has a refractive index identical to that of the lens array body, wherein an optical path of the light emitted from each of the plurality of light emitting elements in an predetermined range on an incident side onto the first optical surface, and an optical path of the light emitted from each of the plurality of light emitting elements on an emitting side from the second optical surface are located on an identical line. 
         [0023]    An optical module of the present invention adopts a configuration including the aforementioned lens array, and the aforementioned optoelectric converting device corresponding thereto. 
       Advantageous Effects of Invention 
       [0024]    The present invention can securely acquire monitor light and realize facilitation of manufacturing. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0025]      FIG. 1  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 1 of the lens array and the optical module provided therewith according to the present invention; 
           [0026]      FIG. 2  is a plan view of the lens array shown in  FIG. 1 ; 
           [0027]      FIG. 3  is a left side view of the lens array shown in  FIG. 1 ; 
           [0028]      FIG. 4  is a right side view of the lens array shown in  FIG. 1 ; 
           [0029]      FIG. 5  is a bottom view of the lens array shown in  FIG. 1 ; 
           [0030]      FIG. 6  is a configurational diagram schematically showing a variation of Embodiment 1; 
           [0031]      FIG. 7  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 2 of the lens array and the optical module provided therewith according to the present invention; 
           [0032]      FIG. 8  is a plan view of the lens array shown in  FIG. 7 ; 
           [0033]      FIG. 9  is a left side view of  FIG. 8 ; 
           [0034]      FIG. 10  is a right side view of  FIG. 8 ; 
           [0035]      FIG. 11  is a bottom view of  FIG. 8 ; 
           [0036]      FIG. 12  is a configurational diagram schematically showing a variation of Embodiment 2; 
           [0037]      FIG. 13  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 3 of the lens array and the optical module provided therewith according to the present invention; 
           [0038]      FIG. 14  is a plan view of the lens array shown in  FIG. 13 ; 
           [0039]      FIG. 15  is a right side view of  FIG. 14 ; 
           [0040]      FIG. 16  is a configurational diagram schematically showing a first variation of Embodiment 3; 
           [0041]      FIG. 17  is a configurational diagram schematically showing a second variation of Embodiment 3; 
           [0042]      FIG. 18  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 4 of the lens array and the optical module provided therewith according to the present invention; 
           [0043]      FIG. 19  is a configurational diagram schematically showing a variation of Embodiment 4; 
           [0044]      FIG. 20  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 5 of the lens array and the optical module provided therewith according to the present invention; 
           [0045]      FIG. 21  is a configurational diagram of a variation of Embodiment 5; 
           [0046]      FIG. 22  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 6 of the lens array and the optical module provided therewith according to the present invention; 
           [0047]      FIG. 23  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 7 of the lens array and the optical module provided therewith according to the present invention; 
           [0048]      FIG. 24  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 8 of the lens array and the optical module provided therewith according to the present invention; 
           [0049]      FIG. 25  is a plan view of the lens array shown in  FIG. 24 ; 
           [0050]      FIG. 26  is a left side view of the lens array shown in  FIG. 24 ; 
           [0051]      FIG. 27  is a bottom view of the lens array shown in  FIG. 24 ; 
           [0052]      FIG. 28  is a configurational diagram schematically showing a variation of Embodiment 8; 
           [0053]      FIG. 29  is a configurational diagram schematically showing another mode of the lens array; 
           [0054]      FIG. 30  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 9 of the lens array and the optical module provided therewith according to the present invention; 
           [0055]      FIG. 31  is a plan view of the lens array shown in  FIG. 30 ; 
           [0056]      FIG. 32  is a left side view of the lens array shown in  FIG. 30 ; 
           [0057]      FIG. 33  is a right side view of the lens array shown in  FIG. 30 ; 
           [0058]      FIG. 34  is a bottom view of the lens array shown in  FIG. 30 ; 
           [0059]      FIG. 35  is a configurational diagram schematically showing a variation of Embodiment 9; 
           [0060]      FIG. 36  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 10 of the lens array and the optical module provided therewith according to the present invention; 
           [0061]      FIG. 37  is a plan view of the lens array shown in  FIG. 36 ; 
           [0062]      FIG. 38  is a left side view of  FIG. 37 ; 
           [0063]      FIG. 39  is a right side view of  FIG. 37 ; 
           [0064]      FIG. 40  is a bottom view of  FIG. 37 ; 
           [0065]      FIG. 41  is a configurational diagram schematically showing a variation of Embodiment 10; 
           [0066]      FIG. 42  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 11 of the lens array and the optical module provided therewith according to the present invention; 
           [0067]      FIG. 43  is a plan view of the lens array shown in  FIG. 42 ; 
           [0068]      FIG. 44  is a right side view of  FIG. 42 ; 
           [0069]      FIG. 45  is a configurational diagram schematically showing a first variation of Embodiment 11; 
           [0070]      FIG. 46  is a configurational diagram schematically showing a second variation of Embodiment 11; 
           [0071]      FIG. 47  is a diagram schematically showing an embodiment of the present invention different from Embodiments 9 to 11; 
           [0072]      FIG. 48  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 12 of the lens array and the optical module provided therewith according to the present invention; 
           [0073]      FIG. 49  is a plan view of the lens array shown in  FIG. 48 ; 
           [0074]      FIG. 50  is a left side view of the lens array shown in  FIG. 48 ; 
           [0075]      FIG. 51  is a right side view of the lens array shown in  FIG. 48 ; 
           [0076]      FIG. 52  is a bottom view of the lens array shown in  FIG. 48 ; 
           [0077]      FIG. 53  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in a variation of Embodiment 12; 
           [0078]      FIG. 54  is a plan view of the lens array shown in  FIG. 53 ; 
           [0079]      FIG. 55  is a left side view of  FIG. 54 ; 
           [0080]      FIG. 56  is a right side view of  FIG. 54 ; 
           [0081]      FIG. 57  is a bottom view of  FIG. 54   
           [0082]      FIG. 58  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 13 of the lens array and the optical module provided therewith according to the present invention; 
           [0083]      FIG. 59  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 14 of the lens array and the optical module provided therewith according to the present invention; 
           [0084]      FIG. 60  is a bottom view of the lens array shown in  FIG. 59 ; 
           [0085]      FIG. 61  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in a variation of Embodiment 14; 
           [0086]      FIG. 62  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 15 of the lens array and the optical module provided therewith according to the present invention; and 
           [0087]      FIG. 63  is a configurational diagram schematically showing an overview of an optical module together with a longitudinal sectional view of a lens array in Embodiment 16 of the lens array and the optical module provided therewith according to the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiment 1 
       [0088]    Embodiment 1 of a lens array and an optical module provided therewith according to the present invention will now be described with reference to  FIGS. 1 to 6 . 
         [0089]      FIG. 1  is a configurational diagram schematically showing an overview of optical module  1  in this embodiment together with a longitudinal sectional view of lens array  2  in this embodiment.  FIG. 2  is a plan view of lens array  2  shown in  FIG. 1 .  FIG. 3  is a left side view of lens array  2  shown in  FIG. 1 .  FIG. 4  is a right side view of lens array  2  shown in  FIG. 1 .  FIG. 5  is a bottom view of lens array  2  shown in  FIG. 1 . 
         [0090]    As shown in  FIG. 1 , lens array  2  in this embodiment is disposed between optoelectric converting device  3  and optical fiber  5 . 
         [0091]    Here, optoelectric converting device  3  includes a plurality of light emitting elements  7  that emit laser light L toward a surface of semiconductor substrate  6  facing lens array  2  in the direction perpendicular to this surface (upper direction in  FIG. 1 ). Light emitting elements  7  constitute a vertical cavity surface emitting laser (VCSEL). In  FIG. 1 , light emitting elements  7  are arranged in line along the direction perpendicular to the sheet of  FIG. 1 . Furthermore, optoelectric converting device  3  includes a plurality of light receiving elements  8  at left adjacent positions of  FIG. 1  to the respective light emitting elements  7 , on a surface of semiconductor substrate  6  facing lens array  2 . Light receiving elements  8  receive monitor light M for monitoring of an output of laser light L (e.g. intensity and amount of light) emitted from respective light emitting elements  7 , and are provided equal in number to light emitting elements  7 . Light receiving elements  8  are arranged in line along the direction identical to the alignment direction of light emitting elements  7  disposed in arrangement in line. The positions of light emitting elements  7  and light receiving elements  8 , which correspond to each other, in the alignment direction match with each other. That is, light receiving elements  8  are arranged at the same pitch as light emitting elements  7 . Light receiving elements  8  may be photo-detectors. Furthermore, although not shown, optoelectric converting device  3  is connected with a control circuit that controls an output of laser light L emitted from light emitting elements  7  on the basis of the intensity or amount of monitor light M received by light receiving elements  8 . For instance, such optoelectric converting device  3  is disposed opposite to lens array  2  such that a contact part (not shown) with lens array  2  is in contact with lens array  2 . Optoelectric converting device  3  is attached to lens array  2  by publicly known fixation means. 
         [0092]    Optical fibers  5  in this embodiment are provided equal in number to light emitting elements  7  and light receiving elements  8 . In  FIG. 1 , optical fibers  5  are arranged in line along the direction perpendicular to the sheet of  FIG. 1 . Optical fibers  5  are arranged at the same pitch as light emitting elements  7 . Each optical fiber  5  is attached to lens array  2  by publicly known fixation means in the state where a part of the fiber on a side of end face  5   a  is held in bulk multicore connector  10 . 
         [0093]    Lens array  2  optically couples light emitting elements  7  and end faces  5   a  of respective optical fibers  5  to each other in the state of being disposed between optoelectric converting device  3  and optical fibers  5 . 
         [0094]    Lens array  2  is further described; as shown in  FIG. 1 , lens array  2  includes lens array body  4 . Lens array body  4  is formed to have a substantially trapezoidal external shape in a longitudinal sectional view, a substantially rectangular shape in a plan view as shown in  FIG. 2 , and a rectangular shape in a side view as shown in  FIGS. 3 and 4 . 
         [0095]    As shown in  FIGS. 1 and 5 , lens array  2  has a plurality of (eight) first lens surfaces (convex lens surfaces)  11  that are plano-convex and equal in number to light emitting elements  7 , on bottom face  4   a  (plane) as a first surface of lens array body  4  in  FIG. 1  facing optoelectric converting device  3 . The plurality of first lens surfaces  11  are arranged in line along the predetermined alignment direction (direction perpendicular to the sheet of  FIG. 1 , longitudinal direction in  FIG. 5 ) corresponding to light emitting elements  7 . First lens surfaces  11  are arranged at the same pitch as light emitting elements  7 . Furthermore, as shown in  FIG. 1 , optical axis OA( 1 ) on each first lens surface  11  coincides with the central axis of laser light L emitted from light emitting element  7  corresponding to first lens surface  11 . 
         [0096]    As shown in  FIG. 1 , laser light L emitted from each light emitting element  7  corresponding to first lens surface  11  is incident on first lens surface  11 . Each first lens surface  11  collimates incident laser light L from light emitting element  7 , and causes the collimated light to move forth into lens array body  4 . 
         [0097]    As shown in  FIGS. 1 and 3 , lens array  2  has a plurality of second lens surfaces (convex lens surfaces)  12  equal in number to first lens surfaces  11 , on left end face  4   b  (plane) in  FIG. 1  as a second surface of lens array body  4  facing the end faces of optical fibers  5 . The plurality of second lens surfaces  12  are arranged in line along the same direction as the alignment direction of first lens surfaces  11 . Second lens surfaces  12  are arranged at the same pitch as first lens surfaces  11 . Optical axis OA( 2 ) on each second lens surface  12  is preferably located on the same axis as the central axis of end face  5   a  of optical fiber  5  corresponding to second lens surface  12 . 
         [0098]    As shown in  FIG. 1 , laser light L from each light emitting element  7 , having been incident on first lens surface  11  corresponding to second lens surface  12  and traveled moved forth through an optical path in lens array body  4 , is incident on second lens surface  12  in the state where the central axis of the laser light coincides with optical axis OA( 2 ) on second lens surface  12 . Each second lens surface  12  emits incident laser light L from light emitting element  7  toward end face  5   a  of optical fiber  5  corresponding to second lens surface  12 . 
         [0099]    Thus, light emitting elements  7  and respective end faces  5   a  of optical fibers  5  are optically coupled to each other via first lens surfaces  11  and second lens surfaces  12 . 
         [0100]    Furthermore, as shown in  FIGS. 1 and 5 , third lens surfaces  13  equal in number to light receiving elements  8  (also equal in number to light emitting elements  7 , optical fibers  5 , first lens surfaces  11  and second lens surfaces  12  in this embodiment) are formed at left adjacent positions of  FIG. 1  to first lens surfaces  11 , on bottom face  4   a  of lens array body  4 . Third lens surfaces  13  are arranged in line along the predetermined alignment direction corresponding to light receiving elements  8 , that is, the same direction as the alignment direction of first lens surface  11 . Third lens surfaces  13  are arranged at the same pitch as light receiving elements  8 . Optical axis OA( 3 ) on each third lens surface  13  preferably coincides with the central axis of light receiving surface of light receiving element  8  corresponding to third lens surface  13 . 
         [0101]    As shown in  FIG. 1 , monitor light M from each light emitting element  7  corresponding to third lens surface  13  is incident on third lens surface  13  from the inside of lens array body  4 . Each third lens surface  13  emits incident monitor light M from light emitting element  7  toward light receiving element  8  corresponding to third lens surface  13 . 
         [0102]    Furthermore, as shown in  FIGS. 1 and 4 , lens array body  4  includes total reflection surface  4   d  at the right upper end in  FIG. 1 . Total reflection surface  4   d  is formed into an inclining surface where the upper end is located left to the bottom end in  FIG. 1  (i.e. on a side of after-mentioned concave part  14 ). Total reflection surface  4   d  lies in the optical path of laser light L emitted from each light emitting element  7 , between first lens surface  11  and after-mentioned first optical surface  14   a  of concave part  14 . 
         [0103]    As shown in  FIG. 1 , laser light L from each light emitting element  7 , having been incident on first lens surface  11 , is incident on such total reflection surface  4   d  from the bottom in  FIG. 1  at an incident angle of at least a critical angle. Total reflection surface  4   d  totally reflects incident laser light L from each light emitting element  7  toward the left in  FIG. 1 . 
         [0104]    Note that a reflection film made of Au, Ag, Al or the like may be coated onto total reflection surface  4   d.    
         [0105]    As shown in  FIGS. 1 and 2 , concave part  14  is formed on top face  4   c  (plane) of lens array body  4  in  FIG. 1  as a third surface. Concave part  14  is formed in a reentrant manner so that the optical paths connecting first lens surfaces  11  and second lens surfaces  12  pass through therein. Top face  4   c  is formed parallel to bottom face  4   a.    
         [0106]    Here, as shown in  FIG. 1 , concave part  14  has first optical surface  14   a  forming a part of the inner surface (right side face of concave part  14  in  FIG. 1 ). First optical surface  14   a  is formed into an inclining surface having a predetermined inclining angle to left end face  4   b  where the upper end is located right to the bottom end in  FIG. 1  (i.e. on a side of total reflection surface  4   d ). 
         [0107]    As shown in  FIG. 1 , laser light L from each light emitting element  7 , having been totally reflected by total reflection surface  4   d , is incident on such first optical surface  14   a  at a predetermined incident angle. This incident angle (i.e. incident direction) is perpendicular to left end face  4   b.    
         [0108]    As shown in  FIG. 1 , concave part  14  has second optical surface  14   b , which is a part of the inner surface and opposite to first optical surface  14   a  at the left in  FIG. 1  (left side face of concave part  14  in  FIG. 1 ). Second optical surface  14   b  is formed parallel to left end face  4   b.    
         [0109]    As shown in  FIG. 1 , laser light L from each light emitting element  7 , having been incident on first optical surface  14   a  and subsequently moved forth toward second lens surface  12  side, is incident on such second optical surface  14   b  perpendicularly to second optical surface  14   b . Second optical surface  14   b  allows incident laser light L from each light emitting element  7  to pass perpendicularly to the surface. 
         [0110]    Furthermore, as shown in  FIG. 1 , prism  16  having a trapezoidal longitudinal section is disposed in a space formed by concave part  14 . Prism  16  is formed to have the same refractive index as that of lens array body  4 . Prism  16  may be made of the same material as that of lens array body  4  (e.g. resin material, such as polyetherimide). For instance, in the case where lens array body  4  and prism  16  are made of Ultem made by SABIC as a polyetherimide, the refractive indices of lens array body  4  and prism  16  are 1.64 for light with a wavelength of 850 nm. In the case where lens array body  4  and prism  16  are made of ARTON made by JSR as an annular olefin resin, the refractive index is 1.50 for light with a wavelength of 850 nm. 
         [0111]    Here, as shown in  FIG. 1 , prism  16  has first prism surface  16   a  forming a part of the surface of this prism (right side face of prism  16  in  FIG. 1 ). First prism surface  16   a  is disposed at a position adjacent to first optical surface  14   a . First prism surface  16   a  may be disposed parallel to first optical surface  14   a.    
         [0112]    Furthermore, as shown in  FIG. 1 , prism  16  has second prism surface  16   b  forming a part of the surface of this prism (left side face of prism  16  in  FIG. 1 ). Second prism surface  16   b  is disposed parallel to second optical surface  14   b  at a position facing second optical surface  14   b  at a predetermined interval from second optical surface  14   b  in the right direction in  FIG. 1 . 
         [0113]    Prism  16  forms the optical path of laser light L from each light emitting element  7 , having been incident on first optical surface  14   a  and subsequently moved forth toward second lens surface  12  side. 
         [0114]    Furthermore as shown in  FIG. 1 , lens array body  4  includes reflecting/transmitting layer  17  that intervenes between first optical surface  14   a  and first prism surface  16   a  and has a small thickness. The surface of reflecting/transmitting layer  17  on the side of first optical surface  14   a  is closely contact with first optical surface  14   a . The surface of reflecting/transmitting layer  17  on the side of first prism surface  16   a  is closely contact with first prism surface  16   a.    
         [0115]    Here, as shown in  FIG. 1 , laser light L from each light emitting element  7 , having been incident on first optical surface  14   a , is directly incident on reflecting/transmitting layer  17 . Note that the incident angle of laser light L from each light emitting element  7  onto reflecting/transmitting layer  17  is identical to the incident angle of laser light L from each light emitting element  7  onto first optical surface  14   a . Reflecting/transmitting layer  17  reflects incident laser light L from each light emitting element  7  at a predetermined reflectance toward third lens surface  13  side while allowing the light to pass through at a predetermined transmittance toward prism  16  side. Reflectance and transmittance of reflecting/transmitting layer  17  can be set to desired values in accordance with the material, thickness and the like of reflecting/transmitting layer  17  within a limit where an amount of monitor light M that is considered sufficient for monitoring the output of laser light L can be acquired. For instance, in the case where reflecting/transmitting layer  17  is formed of a single film made of a single metal, such as Ni, Cr or Al, the reflectance of reflecting/transmitting layer  17  may be 20% and the transmittance thereof may be 60% (absorptance of 20%), which, however, depends on the thickness. For instance, in the case where reflecting/transmitting layer  17  is formed of a dielectric multilayer film made by alternately stacking dielectrics with different permittivities (e.g. Tiθ 2  and Siθ 2 ), the reflectance of reflecting/transmitting layer  17  may be 10% and the transmittance thereof may be 90%, which, however, depends on the thickness and the number of layers. 
         [0116]    As shown in  FIG. 1 , in such reflection or transmission, reflecting/transmitting layer  17  reflects a part of laser light L from each light emitting element  7  (light of the amount of reflectance), having been incident on reflecting/transmitting layer  17 , as monitor light M from light emitting element  7  that corresponds to each light emitting element  7 , toward third lens surface  13  side corresponding to monitor light M. 
         [0117]    Monitor light M from each light emitting element  7  thus reflected by reflecting/transmitting layer  17  moves forth in lens array body  4  toward third lens surface  13  side and is subsequently emitted from third lens surface  13  toward corresponding light receiving element  8 . 
         [0118]    Meanwhile, laser light L from each light emitting element  7 , having passed through reflecting/transmitting layer  17 , is incident on first prism surface  16   a  immediately after passing. The incident direction of laser light L from each light emitting element  7  onto first prism surface  16   a  can be regarded as the same as the incident direction of laser light L from each light emitting element  7  onto first optical surface  14   a . This is because reflecting/transmitting layer  17  is significantly thin and refraction of laser light L at reflecting/transmitting layer  17  can almost be neglected. Laser light L from each light emitting element  7 , having been incident on first prism surface  16   a  moves forth through the optical path in prism  16  toward second lens surface  12  side. 
         [0119]    At this time, prism  16  is formed to have the same refractive index as that of lens array body  4 . Accordingly, when laser light L from each light emitting element  7  is incident on first prism surface  16   a , laser light L is not refracted. Laser light L from each light emitting element  7 , having moved forth through the optical path in prism  16 , is perpendicularly incident on second prism surface  16   b , and emitted from second prism surface  16   b  to the outside of prism  16  perpendicularly to second prism surface  16   b.    
         [0120]    As shown in  FIG. 1 , lens array body  4  includes filler  18  that has a predetermined refractive index and is inserted between second optical surface  14   b  and second prism surface  16   b . Here, as shown in  FIG. 1 , laser light L from each light emitting element  7 , having been emitted from second prism surface  16   b , is incident on surface (hereinafter, referred to as incident side surface)  18   a  of filler  18  on the side of second prism surface  16   b  perpendicularly to second prism surface  16   b . Laser light L from each light emitting element  7 , having been incident on incident side surface  18   a , moves forth through the optical path in filler  18  without refraction toward second lens surface  12  side. Further, laser light L from each light emitting element  7 , having moved forth through the optical path in filler  18 , is perpendicularly incident on surface (hereinafter, referred to as emitting side surface)  18   b  of filler  18  on the side of second optical surface  14   b , and emitted from emitting side surface  18   b  to the outside of filler  18  perpendicularly to emitting side surface  18   b.    
         [0121]    Laser light L from each light emitting element  7 , having thus emitted from filler  18  perpendicularly to emitting side surface  18   b , is incident on second optical surface  14   b  immediately after emission as described above. Laser light L from each light emitting element  7 , having been perpendicularly incident on second optical surface  14   b , moves forth through the optical path in lens array body  4  after second optical surface  14   b  toward each second lens surface  12  side and is subsequently emitted from second lens surface  12  toward the end face of corresponding optical fiber  5 . 
         [0122]    The aforementioned configuration allows reflecting/transmitting layer  17  between first optical surface  14   a  and first prism surface  16   a  to split laser light L from each light emitting element  7 , having been incident on first lens surface  11 , toward second lens surface  12  side and third lens surface  13  side. Monitor light M split toward third lens surface  13  side is emitted from each third lens surface  13  toward light receiving element  8  side. As a result, monitor light M can be securely acquired. Adoption of reflecting/transmitting layer  17  capable of being easily formed to have a certain extent of area, as a configuration of acquiring such monitor light M, facilitates manufacturing of lens array  2 . 
         [0123]    According to this embodiment, prism  16  is formed to have the same refractive index as that of lens array body  4 , thereby allowing the optical path of laser light L from each light emitting element  7  in prism  16  to be maintained perpendicular to left end face  4   b . Furthermore, laser light L from each light emitting element  7 , having thus moved forth through the optical path in prism  16  can sequentially be incident perpendicularly to second prism surface  16   b  and second optical surface  14   b . This allows the optical path of laser light L from each light emitting element  7  in lens array body  4  to be aligned on the same line between an incident side onto first optical surface  14   a  (between total reflection surface  4   d  and first optical surface  14   a  in  FIG. 1 ) and an emitting side from second optical surface  14   b . As a result, for instance, in the case of product inspection, this can reduce the number of spots required to be adjusted in measurements (modification of a mold shape etc.) for canceling a deviation from the center of each second lens surface  12  concerning laser light L, which has been from each light emitting element  7  and incident on each second lens surface  12 , if such a deviation is confirmed. In the case of a configuration incapable of aligning the optical path on the incident side onto first optical surface  14   a  and the optical path on the emitting side from second optical surface  14   b  on the same line, the measurements of optical surfaces  14   a  and  14   b  of concave part  14  and prism surfaces  16   a  and  16   b  of prism  16  (including the inclining angle) are sometimes required to be adjusted for correcting the axial deviation of incident light on second lens surface  12 . In contrast, according to this embodiment, if only accuracy in measuring is secured such that the total reflection direction at total reflection surface  4   d  is perpendicular to left end face  4   b  and further second optical surface  14   b  and second prism surface  16   b  are parallel to left end face  4   b , complicated measurement adjustment to reset optimal inclining angles relative to respective surfaces  14   a ,  14   b ,  16   a  and  16   b  is not required. This can contribute to further facilitation of manufacturing lens array  2 . 
         [0124]    Furthermore, according to this embodiment, second optical surface  14   b  is formed parallel to left end face  4   b , thereby allowing design of second optical surface  14   b  and determination of accuracy in measuring thereof to be simplified. 
         [0125]    Moreover, according to this embodiment, filler  18  is inserted between second optical surface  14   b  and second prism surface  16   b . Accordingly, even if a scratch is formed on second optical surface  14   b , reflection or scattering of laser light L on second optical surface  14   b  caused by the scratch can be suppressed. The effect of suppressing reflected/scattered light owing to filler  18  is based on the same principle as a principle that drops of water applied onto a surface of frosted glass cover irregularities thereat and the frosted glass becomes transparent. Here, reflection and scattering of laser light L cause occurrence of stray light or reduction in coupling efficiency with an end face of the optical fiber. Accordingly, suppression thereof is significantly important in terms of securing optical performance. In particular, such an effect of suppressing reflected light or scattered light is effective in the case where lens array body  4  is acquired by injection molding of resin material (polyetherimide, etc.) using a mold. More specifically, in the case of forming lens array body  4  by injection molding, a molded piece having a shape transferred from concave part  14  is released from the mold. According to this embodiment, as described above, in terms of simplifying design and determination of accuracy in measuring, second optical surface  14   b  is formed parallel to left end face  4   b  (i.e. perpendicular to top face  4   c ). In demolding, the piece is demolded such that the mold slides in the direction of the surface of second optical surface  14   b . In this case, second optical surface  14   b  is susceptible to damage. Accordingly, with the configuration of second optical surface  14   b  having high frequency of occurrence of a scratch, it is significantly important to provide filler  18  that avoids malfunction on optical performance due to the scratch. As a result, manufacturing and handling (e.g. determination of accuracy in measuring) are facilitated by forming second optical surface  14   b  parallel to left end face  4   b , as well as occurrence of stray light and reduction in coupling efficiency is suppressed, i.e. optical performance is secured, by suppressing reflected light or scattered light on second optical surface  14   b.    
         [0126]    In addition to the configuration, reflecting/transmitting layer  17  may be formed by coating first prism surface  16   a  or first optical surface  14   a  with the aforementioned metal single layer film or dielectric multilayer film. A publicly known coating technique, such as Inconel deposition, can be adopted as the coating. This allows the configuration of reflecting/transmitting layer  17  to be simplified, thereby enabling further facilitation of manufacturing to be realized. Furthermore, reflecting/transmitting layer  17  can be formed significantly thinly (e.g. 1 μm or less). This allows refraction of laser light L from each light emitting element  7  passing through reflecting/transmitting layer  17  to be significantly small to such an extent that it can be neglected, and enables straightness of light before and after incident on prism  16  to be secured. Moreover, the optical path on the incident side onto first optical surface  14   a  and the optical path on the emitting side from second optical surface  14   b  can be securely aligned on the same line, thereby contributing to further facilitation of manufacturing. However, the present invention is not limited to such a configuration. Instead, for instance, reflecting/transmitting layer  17  may be made of a glass filter. 
         [0127]    In addition to the configuration, light-transmitting adhesive may be used as filler  18 , and prism  16  may be bonded to concave part  14  with filler  18 . This allows filler  18  to also serve as adhesive for bonding prism  16  to lens array body  4 . As a result, cost can be reduced. For instance, thermosetting resin or ultraviolet-setting resin may be adopted as such filler  18  that also serves as light-transmitting adhesive. 
         [0128]    In addition to the configuration, it is preferred that the difference of refractive indices between filler  18  and lens array body  4  be a predetermined value of 0.35 or less. According to this configuration, Fresnel reflection at the interface between second prism surface  16   b  and filler  18  and Fresnel reflection at the interface between filler  18  and left end face  4   b  can be suppressed, thereby occurrence of stray light and reduction in coupling efficiency to be suppressed more securely. In the case of forming lens array body  4  using the aforementioned Ultem made by SABIC, for instance LPC1101 made by Mitsubishi Gas Chemical Company can be used as filler  18 . As to this product, the refractive index of light with wavelength of 850 nm, which is calculated on the basis of the refractive index and Abbe number for d line and disclosed by the manufacturer, is 1.66. Furthermore, use of LPJ1104 made by the same manufacturer allows a refractive index of 1.64 for wavelength of 850 nm to be acquired. 
         [0129]    Besides that, in the case of forming lens array body  4  using the aforementioned ARTON made by JSR, suitable filler  18  may be A1754B made by TECS, which is UV-curable resin. The refractive index of this product for light with a wavelength of 850 nm is 1.50. In this case, the difference of refractive indices between lens array body  4  and filler  18  is 0. 
         [0130]    In addition to the configuration, the inclining angle of total reflection surface  4   d  is preferably within a range from 40° to 50° (more preferably, 45°) in the clockwise direction in  FIG. 1  with reference to bottom face  4   a (0°). The inclining angle of first optical surface  14   a  is preferably within a range from 40° to 50° (more preferably, 45°) in the counterclockwise direction in  FIG. 1  with reference to bottom face  4   a (0°). In the case of adopting left end face  4   b  as a reference (0°), a preferable range of such an inclining angle of first optical surface  14   a  is from 40° to 50° (more preferably, 45°) in the clockwise direction in this diagram. This configuration allows a reasonable design for totally reflecting incident laser light L from each light emitting element  7  on total reflection surface  4   d  toward concave part  14  side and for splitting laser light L incident on first optical surface  14   a  toward second lens surface  12  side and third lens surface  13  side. In particular, in the case where the inclining angles of total reflection surface  4   d  and first optical surface  14   a  are 45°, the design of total reflection surface  4   d  and first optical surface  14   a  and determination of accuracy in measuring thereof are more simplified. 
         [0131]    In addition to the configuration, bottom face  4   a  and left end face  4   b  may be formed perpendicular to each other. Optical axis OA( 1 ) on first lens surface  11  and optical axis OA( 3 ) on third lens surface  13  may be formed perpendicular to bottom face  4   a . Optical axis OA( 2 ) on second lens surface  12  may be formed perpendicular to left end face  4   b . This configuration can relax accuracy in measuring that is required for lens array  2  to secure the optical path connecting light emitting element  7  and light receiving element  8  and the optical path connecting light emitting element  7  and the end face of optical fiber  5 , thereby allowing further facilitation of manufacturing to be realized. More specifically, for instance, in the case where optical axis OA( 3 ) on third lens surface  13  is configured to be inclined at an acute angle to optical axis OA( 1 ) on first lens surface  11 , there is a possibility that a slight measurement error in the longitudinal direction in  FIG. 1  prevents monitor light M, having been emitted from third lens surface  13 , from being coupled to light receiving element  8 . In contrast, in this embodiment, optical axis OA( 1 ) on first lens surface  11  and optical axis OA( 3 ) on third lens surface  13  are parallel to each other. By this means, even if lens array  2  causes a slight measurement error in the longitudinal direction in  FIG. 1 , the beam diameter of monitor light M emitted from third lens surface  13  merely becomes larger or smaller with respect to a designed value, thus allowing the monitor light M to be appropriately received by each light receiving element  8 . If optical axis OA( 2 ) on second lens surface  12  has an angle other than a right angle to optical axis OA( 1 ) on first lens surface  11 , there is a possibility that a slight measurement error in the lateral direction in  FIG. 1  prevents laser light L, having been emitted from second lens surface  12 , from being coupled to the end face of optical fiber  5 . In contrast, in this embodiment, optical axis OA( 1 ) on first lens surface  11  and optical axis OA( 2 ) on second lens surface  12  are formed to be perpendicular to each other. By this means, even if lens array  2  causes a slight measurement error in the lateral direction in  FIG. 1 , the beam diameter of laser light L emitted from second lens surface  12  merely becomes slightly larger or smaller with respect to a designed value, thus allowing the laser light L to be appropriately coupled to the end face of optical fiber  5   
         [0132]    In addition to the configuration, in this embodiment, as shown in  FIGS. 1 and 2 , concave part  14  is formed into a shape accommodating bottom surface (bottom face in  FIG. 1 )  14   e  and all sides  14   a  to  14   d  of concave part  14  within a range indicated by the external shape of opening  14   f  of concave part  14  in the case of being viewed in the plane normal direction of top face  4   c  (from the top in  FIG. 1 ). In other words, concave part  14  is formed so as to accommodate projected surfaces of bottom surface  14   e  and all sides  14   a  to  14   d  in the plane normal direction of top face  4   c  within the range indicated by the external shape of opening  14   f . As shown in  FIG. 2 , opening  14   f  is formed into a rectangular shape elongated in the longitudinal direction in  FIG. 2  and encompassed therearound by top face  4   c . Sides  14   b  to  14   d  other than first optical surface  14   a  are formed perpendicular to top face  4   c . This allows concave part  14  to be formed into a shape capable of securing demoldability from the mold. This can realize effective manufacturing of lens array  2  using the mold. 
         [0133]    Third lens surfaces  13  and light receiving elements  8  corresponding thereto are not necessarily provided so as to be equal in number to light emitting elements  7 . It is sufficient that at least one set is provided. In this case, at reflecting/transmitting layer  17 , in laser light L from each light emitting element  7  incident on each first lens surface  11 , only a part of laser light L to which third lens surfaces  13  correspond is reflected as monitor light M. The other part of laser light L is reflected but is not used as monitor light M. 
         [0134]    In the configuration in  FIG. 1 , top face  16   c  of prism  16  is at the same plane as top face  4   c  of lens array body  4 , and bottom face  16   d  of prism  16  is in contact with bottom surface  14   e  of concave part  14 . However, as shown in  FIG. 6 , even if prism  16  is bonded in the state where top face  16   c  of prism  16  protrudes upward from top face  4   c  of lens array body  4 , optical performance is not affected. 
         [0135]    A counter-bore part having a bottom surface parallel to bottom face  4   a  may be provided with a dent in a portion on bottom face  4   a  facing optoelectric converting device  3 . First lens surfaces  11  and third lens surfaces  13  may be formed on bottom surfaces of the counter-bore part. In this case, optoelectric converting device  3  is fixed to lens array  2  in the state where semiconductor substrate  6  is in contact with the inner circumference of the counter-bore part at bottom face  4   a.    
       Embodiment 2 
       [0136]    Embodiment 2 of a lens array and an optical module provided therewith according to the present invention will now be described mainly on difference from Embodiment 1 with reference to  FIGS. 7 to 12 . 
         [0137]    In this embodiment, elements having configurations identical or similar to those in  FIGS. 1 to 6  will be described using the same reference signs as those of  FIGS. 1 to 6 . 
         [0138]      FIG. 7  is a configurational diagram schematically showing an overview of optical module  21  in this embodiment together with a longitudinal sectional view of lens array  22  in this embodiment.  FIG. 8  is a plan view of lens array  22  shown in  FIG. 7 .  FIG. 9  is a left side view of  FIG. 8 .  FIG. 10  is a right side view of  FIG. 8 .  FIG. 11  is a bottom view of  FIG. 8 . 
         [0139]    In this embodiment, as a difference from Embodiment 1, means is provided for mechanically positioning optoelectric converting device  3  and optical fiber  5  when optoelectric converting device  3  and optical fiber  5  are fixed to lens array  22 . 
         [0140]    More specifically, as shown in  FIGS. 7 and 11 , in this embodiment, first lens surfaces  11  and second lens surfaces  12  are formed on bottom surface  23   a  of first counter-bore part  23  (first surface in this embodiment) provided with a dent in bottom face  4   a  of lens array body  4 . Bottom surface  23   a  of first counter-bore part  23  is formed parallel to bottom face  4   a . As shown in  FIG. 11 , first counter-bore part  23  is formed to have such a width in the longitudinal direction in  FIG. 11  (hereinafter, referred to as the lens alignment direction) that the widthwise edges of first counter-bore part  23  are disposed slightly outwardly from lens surfaces  11  and  13  that are arranged outermost in the lens alignment direction. In this embodiment, lens array body  4  is formed wider in the lens alignment direction than the width of first counter-bore part  23  in the lens alignment direction. In accordance with this, as shown in  FIG. 11 , bottom face  4   a  includes portions that extend outwardly in the lens alignment direction from both ends of first counter-bore part  23 . As shown in  FIG. 11 , at the both extended portions of bottom face  4   a  extending outwardly in the lens alignment direction from both ends of first counter-bore part  23 , two pairs, four in total, of plano-convex fitting holes  24  are formed so as to be disposed across first counter-bore part  23  for positioning optoelectric converting device  3 . Fitting holes  24  are fitted with fitting pins, not shown, penetrating through semiconductor substrate  6  in the state where semiconductor substrate  6  is in contact with extended portions of bottom face  4   a . This allows optoelectric converting device  3  to be mechanically positioned when optoelectric converting device  3  is fixed to lens array  22 . 
         [0141]    As shown in  FIGS. 7 and 9 , in this embodiment, second lens surfaces  12  are formed on bottom surface  26   a  (second surface in this embodiment) of second counter-bore part  26  provided with a dent in left end face  4   b  of lens array  4 . Bottom surface  26   a  of second counter-bore part  26  is formed parallel to left end face  4   b . As shown in  FIG. 9 , second counter-bore part  26  is formed to have such a width in lens alignment direction that the widthwise edges of second counter-bore part  26  are disposed slightly outwardly from lens surfaces  12  arranged outermost in the lens alignment direction. As shown in  FIG. 9 , in this embodiment, left end face  4   b  includes portions that extend outwardly in the lens alignment direction from both ends of second counter-bore part  26 . As shown in  FIG. 9 , at the both extended portions of left end face  4   b , a pair, two in total, of fitting pins  27  are formed so as to be disposed across second counter-bore part  26  in a protruding manner as a structure for positioning optical fiber  5 . Fitting pins  27  are fitted into fitting holes, not shown, formed in connector  10  in the state where connector  10  is in contact with the extended portions of left end face  4   b . This allows optical fibers  5  to be mechanically positioned when optical fibers  5  are fixed to lens array  22 . 
         [0142]    As shown in  FIG. 7 , in this embodiment, as to a difference from Embodiment 1, concave part  14  is formed to extend upwardly from first optical surface  14   a  and second optical surface  14   b . In accordance with this, the upper end of lens array body  4  is located upwardly from top face  16   c  of prism  16 . 
         [0143]    In  FIG. 7 , the upper end of lens array body  4  is a plane, or top face  4   c , at the left of concave part  14 . The upper end of lens array body  4  forms a ridge line at the right of concave part  14  by intersection of a portion extending upwardly from first optical surface  14   a  of the inner surface of concave part  14  and an extension of total reflection surface  4   d.    
         [0144]    Furthermore, as shown in  FIG. 7 , in this embodiment, filler  18  fills not only a space between second prism surface  16   b  and second optical surface  14   b  but also a space above top face  16   c  of prism  16 , thereby filling a step between the upper end of lens array body  4  and top face  16   c  of prism  16 . 
         [0145]    The configuration of this embodiment can also exert excellent working-effect similar to those of Embodiment 1. Furthermore, in this embodiment, optoelectric converting device  3  and optical fiber  5  can be simply positioned with respect to lens array  22  using positioning structures  24  and  27 . This allows optoelectric converting device  3  and optical fiber  5  to be simply fixed to lens array  22 . Moreover, in this embodiment, the amount of filler  18  is larger and the adhesive area between prism  16  and concave part  14  is increased in comparison with Embodiment 1. This allows prism  16  to be bonded further firmly to concave part  14 . 
         [0146]    Instead of aforementioned fitting holes  24 , through holes each having the same diameter as that of fitting hole  24  and penetrating lens array body  4  may be formed. As the structure for positioning optical fiber  5 , fitting holes or through holes may be formed on the side of lens array body  4  and fitting pins may be formed on the side of optical fiber  5 . Likewise, as the structure for positioning optoelectric converting device  3 , fitting pins may be formed on the side of lens array body  4  and fitting holes or through holes may be formed on the side of optoelectric converting device  3 . The positioning of optical fiber  5  and optoelectric converting device  3  is not limited to mechanical positioning. Instead, for instance, the positioning may be performed according to an optical method by optically recognizing a mark formed on lens array body  4 . 
         [0147]    (Variation) 
         [0148]    Next,  FIG. 12  shows a variation of this embodiment. Lens array  22  in this variation extends upwardly from top face  16   c  of prism  16  only at left side face of the array in  FIG. 12  including second optical surface  14   b  among the sides of concave part  14 . The other portions are formed to the same height as top face  16   c  of prism  16 . In this variation, filler  18  fills not only a space between second prism surface  16   b  and second optical surface  14   b  but also the space in a manner flowing upwardly therefrom. More specifically, filler  18  fills the space up to the extension upward from second optical surface  14   b  on the left side face of concave part  14  and a predetermined range at the left end side of top face  16   c  of prism  16 . 
       Embodiment 3 
       [0149]    Embodiment 3 of a lens array and an optical module provided therewith according to the present invention will now be described mainly on difference from Embodiments 1 and 2 with reference to  FIGS. 13 to 16 . 
         [0150]    In this embodiment, elements having configurations identical or similar to those in  FIGS. 1 to 12  will be described using the same reference signs as those of  FIGS. 1 to 12 . 
         [0151]      FIG. 13  is a configurational diagram schematically showing an overview of optical module  30  in this embodiment together with a longitudinal sectional view of lens array  31  in this embodiment.  FIG. 14  is a plan view of lens array  31  shown in  FIG. 13 . 
         [0152]      FIG. 15  is a right side view in  FIG. 14 . 
         [0153]    As shown in  FIG. 13 , the configuration in this embodiment is similar to those in Embodiment 2 in that the side surfaces of concave part  14  extend upwardly from first optical surface  14   a  and second optical surface  14   b , and filler  18  fills a space over top face  16   c  of prism  16 . 
         [0154]    However, this embodiment is different from Embodiment 2 in that concave part  14  has a characteristic shape in a part of the inner surface thereof to assist installation of prism  16  into concave part  14 . More specifically, as shown in  FIG. 13 , in this embodiment, bottom surface  14   e  of concave part  14  has a two-step structure. The portion located to the left of prism  16  in  FIG. 13  protrudes upwardly from the remaining portions (a portion in contact with bottom face  16   d  of prism  16 ). The measurements of the remaining portions of bottom surface  14   e  in the lateral direction in  FIG. 13  match with the measurements of bottom face  16   d  of prism  16  in the same direction. 
         [0155]    Bottom surface  14   e  of concave part  14  having such two-step structure can regulate backlash of prism  16  in the lateral direction in  FIG. 13  by means of the step of bottom surface  14   e  in the case where prism  16  is installed in concave part  14  while securing a filling space with filler  18 . This allows bottom surface  14   e  to assist installation of prism  16  into concave part  14 . 
         [0156]    Accordingly, this embodiment can exert advantageous working-effects of Embodiment 1, facilitate installation of prism  16  when prism  16  is bonded to concave part  14 , and further facilitate manufacturing of lens array  31 . 
         [0157]    (First Variation) 
         [0158]    Next,  FIG. 16  shows a first variation of this embodiment. Lens array  31  in this variation corresponds to a configuration where bottom surface  14   e  of concave part  14  of lens array  22  in Embodiment 2 shown in  FIGS. 7 to 11  is formed into the two-step structure as with  FIG. 13 . 
         [0159]    Lens array  31  in this variation can regulate the backlash of prism  16  in the lateral direction in  FIG. 16  by means of the step of bottom surface  14   e  when prism  16  is installed in concave part  14  while securing the filling space with filler  18 , as with lens array  31  shown in  FIGS. 13 to 15 . This allows bottom surface  14   e  to assist installation of prism  16  into concave part  14 . 
         [0160]    (Second Variation) 
         [0161]    Next,  FIG. 17  shows a second variation of this embodiment. Lens array  31  in this variation has a configuration shown in  FIG. 13  or  16  wherein the measurements of bottom surface  16   d  of prism  16  in the lateral direction in  FIG. 17  are larger than those of the portion at the lower step of the two-step structure of bottom surface  14   e  of concave part  14  in the same direction. Accordingly, in lens array  31  of this variation, a space can intentionally be formed between bottom surface  16   d  of prism  16  and the portion at the lower step of bottom surface  14   e  of concave part  14 . Therefore, according to lens array  31  in this variation, as shown in  FIG. 17 , filler  18  can be inserted between bottom surface  16   d  of prism  16  and the portion at the lower step of bottom surface  14   e  of concave part  14 , thereby allowing prism  16  to be fixed further firmly to lens array body  4 . Lens array  31  in this variation allows lens array body  4  to support prism  16  via first optical surface  14   a  and the steps of bottom surface  14   e  such that prism  16  is laterally sandwiched, thereby enabling prism  16  to be stably disposed in concave part  14 . Lens array  31  in this variation can facilitate an operation of fixing prism  16  using filler  18 . 
       Embodiment 4 
       [0162]    Embodiment 4 of a lens array and an optical module provided therewith according to the present invention will now be described mainly on difference from Embodiments 1 to 3 with reference to  FIGS. 18 and 19 . 
         [0163]    In this embodiment, elements having configurations identical or similar to those in  FIGS. 1 to 17  will be described using the same reference signs as those of  FIGS. 1 to 17 . 
         [0164]    As shown in  FIG. 18 , lens array  35  and optical module  34  in this embodiment are different from those in Embodiments 1 to 3 in that first optical surface  14   a  is formed parallel to left end face  4   b.    
         [0165]    As shown in  FIG. 18 , in this embodiment, reflecting/transmitting layer  17  is formed on first prism surface  16   a  having an inclining angle to left end face  4   b . As with Embodiment 1, reflecting/transmitting layer  17  may be formed by coating first prism surface  16   a  with a metal single layer film or a dielectric multilayer film. The preferable range of the inclining angle of first prism surface  16   a  is as shown in Embodiment 1. 
         [0166]    In accordance with the configurations of first optical surface  14   a  and reflecting/transmitting layer  17 , as shown in  FIG. 18 , in this embodiment, a space having a right triangle in a sectional view is formed between first optical surface  14   a  and reflecting/transmitting layer  17 . As shown in  FIG. 18 , in this embodiment, filler  18  fills not only a space between second optical surface  14   b  and second prism surface  16   b  but also a space between first optical surface  14   a  and reflecting/transmitting layer  17 . Filler  18  inserted between first optical surface  14   a  and reflecting/transmitting layer  17  may be integral with filler  18  inserted between second optical surface  14   b  and second prism surface  16   b . In this case, concave part  14  is formed larger in measurements in the lens alignment direction than prism  16  in the lens alignment direction. The portion largely formed in concave part  14  is filled with filler  18 , and filler  18  may be integrated in the front and rear of prism  16 . This configuration allows the contact area between prism  16  and filler  18  to be increased, thereby enabling prism  16  to be fixed further firmly to lens array body  4 . 
         [0167]    In the following description, for the sake of convenience, filler  18  inserted between first optical surface  14   a  and reflecting/transmitting layer  17  is referred to as filler  18  in the front of prism. Filler  18  inserted between second optical surface  14   b  and second prism surface  16   b  is referred to as filler  18  in the rear of prism. 
         [0168]    Furthermore, in this embodiment, prism  16  and filler  18  are formed so as to have the same refractive index. Prism  16  and filler  18  are preferably formed to have the same refractive index as that of lens array body  4 , in order to suppress Fresnel reflection on the interface between lens array body  4  and filler  18 . 
         [0169]    As shown in  FIG. 18 , in this embodiment, the right side face of concave part  14  where first optical surface  14   a  is formed extends upwardly in the perpendicular direction from first optical surface  14   a . Furthermore, in this embodiment, the upper end of prism  16  is located above the upper end of first prism surface  16   a . In accordance with this, the right end face of prism  16  parallel to left end face  4   b  is formed to extend from the upper end of first prism surface  16   a  toward the upper end of prism  16 . As shown in  FIG. 18 , the right end face of prism  16  is in contact with the extension at the right side face of concave part  14  extending upwardly from first optical surface  14   a . This allows prism  16  to be simply disposed at a fixation position in concave part  14 . 
         [0170]    Furthermore, as shown in  FIG. 18 , in this embodiment, plate-shaped flange  36  is formed integrally with prism  16  at the upper end of prism  16 . Flange  36  is formed such that the measurements in lateral direction in  FIG. 18  are larger than the measurements of prism  16  and concave part  14  in the same direction. Prism  16  is stably disposed in concave part  14  such that the undersurface of flange  36  is in contact with the circumference of concave part  14  at top face  4   c  of lens array body  4 . In  FIG. 18 , bottom face  16   d  of prism  16  is in contact with bottom surface  14   e  of concave part  14 . However, as long as flange  36  can secure stability and reliability of prism  16  as with this embodiment, bottom face  16   d  of prism  16  may be located above bottom surface  14   e  of concave part  14 . 
         [0171]    According to such a configuration of this embodiment, laser light L from each light emitting element  7 , having been totally reflected by total reflection surface  4   d , is perpendicularly incident on first optical surface  14   a , and then immediately incident perpendicularly on filler  18  in the front of prism. 
         [0172]    Next, laser light L from each light emitting element  7 , having been incident on filler  18  in the front of prism is not refracted and moves forth through the optical path in filler  18  in the front of prism, and subsequently is incident on reflecting/transmitting layer  17 . The incident direction at this time is perpendicular to left end face  4   b.    
         [0173]    On the traveling path of laser light L thereafter, laser light L from each light emitting element  7  moving forth through reflecting/transmitting layer  17  toward second lens surface  12  side is the same as that described in Embodiment 1. 
         [0174]    Meanwhile, monitor light M from each light emitting element  7 , having been reflected by reflecting/transmitting layer  17  and moved forth toward third lens surface  13  side, moves forth through the optical path in filler  18  in the front of prism, and subsequently is incident on bottom surface  14   e  of concave part  14 . Monitor light M from each light emitting element  7 , having been incident on bottom surface  14   e , moves forth through the optical path in lens array body  4  and subsequently is incident on third lens surface  13 . 
         [0175]    That is, this embodiment allows monitor light M to be securely acquired by reflecting/transmitting layer  17 , as with Embodiment 1. 
         [0176]    In this embodiment, first optical surface  14   a  is formed parallel to left end face  4   b , and prism  16  is formed so as to have the same refractive index as that of filler  18 . Accordingly, this embodiment enables the optical path of laser light L from each light emitting element  7  in filler  18  and prism  16  to be maintained perpendicular to left end face  4   b . Furthermore, laser light L from each light emitting element  7 , having moved forth in filler  18  and prism  16 , can be incident perpendicularly to second optical surface  14   b . Moreover, as with Embodiment 1, the optical path on the incident side onto first optical surface  14   a  and the optical path on the emitting side from second optical surface  14   b  can be aligned on the same line. 
         [0177]    Furthermore, in this embodiment, not only second optical surface  14   b  but also first optical surface  14   a  are formed parallel to left end face  4   b , thereby simplifying design of first optical surface  14   a  and determination of accuracy in measuring thereof. On the other hand, for instance, in demolding of lens array body  4  from the mold in the case of injection molding of lens array body  4 , if a scratch is formed on first optical surface  14   a , filler  18  inserted between first optical surface  14   a  and reflecting/transmitting layer  17  can suppress occurrence of reflected light and scattered light due to the scratch on first optical surface  14   a.    
         [0178]    In the case where the effect of suppressing reflected light or scattered light on second optical surface  14   b  is not required, it is sufficient to fill filler  18  only between first optical surface  14   a  and reflecting/transmitting layer  17 . Also in this case, laser light L from each light emitting element  7 , having moved forth in filler  18  and prism  16 , can sequentially be incident perpendicularly on second prism surface  16   b  and second optical surface  14   b . This allows the optical path on the incident side onto first optical surface  14   a  and the optical path on the emitting side from second optical surface  14   b  to be aligned on the same line. 
         [0179]    As shown in  FIG. 19 , filler  18  may newly be disposed that causes the entire left end face of prism  16  including second prism surface  16   b  to be in contact with the entire left side face of concave part  14  including second optical surface  14   b  and covers the entire flange  36  and circumference of flange  36  on top face  4   c  of lens array body  4  from above. 
         [0180]    Furthermore, in this embodiment (configuration in  FIG. 18 ), bottom surface  14   e  may have a two-step structure to assist installation of prism  16  into concave part  14  as with Embodiment 3. 
       Embodiment 5 
       [0181]    Embodiment 5 of a lens array and an optical module provided therewith according to the present invention will now be described mainly on difference from Embodiment 4 with reference to  FIGS. 20 and 21 . 
         [0182]    In this embodiment, elements having configurations identical or similar to those in  FIGS. 18 and 19  will be described using the same reference signs as those of  FIGS. 18 and 19 . 
         [0183]    As shown in  FIG. 20 , lens array  40  and optical module  39  in this embodiment are formed such that first optical surface  14   a  is parallel to left end face  4   b  as with Embodiment 4. 
         [0184]    Note that, as shown in  FIG. 20 , this embodiment is different from Embodiment 4 in that second prism surface  16   b  is disposed to have a predetermined inclining angle to left end face  4   b . More specifically, as shown in  FIG. 20 , the inclining angle of second prism surface  16   b  is set such that it extends toward first prism surface  16   a  side in the direction from opening  14   f  side to bottom surface  14   e  side of concave part  14 . On the other hand, the inclining angle of first prism surface  16   a  is set such that it extends toward second prism surface  16   b  side in the direction from opening  14   f  side to bottom surface  14   e  side of concave part  14 . Furthermore, as shown in  FIG. 20 , first prism surface  16   a  and second prism surface  16   b  intersect with each other at the bottom ends thereof. Accordingly, in this embodiment, prism  16  reflects such inclining angles of prism surfaces  16   a  and  16   b , and thereby has the entire side shape similar to a home plate. The inclining angle of second prism surface  16   b  is preferably within a range from 40° to 50° (more preferably, 45°) in the counterclockwise direction in  FIG. 20  with reference to left end face  4   b  (0°). 
         [0185]    As shown in  FIG. 20 , in this embodiment, left end face of prism  16  parallel to left end face  4   b  is in contact with a portion extending upwardly in the vertical direction from second optical surface  14   b  of left side face of concave part  14  identically parallel to left end face  4   b.    
         [0186]    This embodiment can also realize the optical path of monitor light M as with that described in Embodiment 4, thereby allowing monitor light to be securely acquired. 
         [0187]    According to this embodiment, laser light L from each light emitting element  7 , having passed through reflecting/transmitting layer  17 , moves forth through the optical path in prism  16  while maintaining linearity to the optical path connecting total reflection surface  4   d  and first optical surface  14   a , and subsequently is incident on filler  18  in the rear of prism via second prism surface  16   b . Here, filler  18  in the rear of prism is formed to have the same refractive index as that of prism  16 . Accordingly, laser light L from each light emitting element  7 , having been incident on filler  18  in the rear of prism, is not refracted and moves forth through the optical path in filler  18 , and subsequently is perpendicularly incident on second optical surface  14   b . Accordingly, as with Embodiment 1, the optical path on the incident side onto first optical surface  14   a  and the optical path on the emitting side from second optical surface  14   b  can be aligned on the same line. 
         [0188]    As shown in  FIG. 21 , in this embodiment, filler  18  may newly be provided that covers the entire flange  36  and circumference of flange  36  at top face  4   c  of lens array body  4  from the above. 
       Embodiment 6 
       [0189]    Embodiment 6 of a lens array and an optical module provided therewith according to the present invention will now be described mainly on difference from Embodiment 5 with reference to  FIG. 22 . 
         [0190]    In this embodiment, elements having configurations identical or similar to those in  FIGS. 20 and 21  will be described using the same reference signs. 
         [0191]    As shown in  FIG. 22 , as to lens array  43  and optical module  42  in this embodiment, first prism surface  16   a  and second prism surface  16   b  are formed into inclining surfaces, as with Embodiment 5. 
         [0192]    Note that this embodiment is different from Embodiment 5 in that first optical surface  14   a  is formed to have a predetermined slight inclining angle to left end face  4   b  and second optical surface  14   b  is formed to have a predetermined slight inclining angle to left end face  4   b . The slight inclining angle of first optical surface  14   a  is set such that first optical surface  14   a  slightly inclines toward second optical surface  14   b  side in the direction from opening  14   f  side to bottom surface  14   e  side of concave part  14 . The slight inclining angle of second optical surface  14   b  is set such that second optical surface  14   b  slightly inclines toward first optical surface  14   a  side in the direction from opening  14   f  side to bottom surface  14   e  side of concave part  14 . 
         [0193]    For instance, the slight inclining angle of first optical surface  14   a  may be in a range from 1° to 3° (preferably, 2°) in the clockwise direction in  FIG. 22  with reference to left end face  4   b (0°). The slight inclining angle of second optical surface  14   b  may be in a range from 1° to 3° (preferably, 2°) in the counterclockwise direction in  FIG. 22  with reference to left end face  4   b  (0°). 
         [0194]    Furthermore, in this embodiment, lens array body  4 , prism  16  and filler  18  (both in the front and rear of prism) are formed to have the same refractive index. In the case of using the aforementioned ARTON as the material of lens array body  4  and prism  16 , the aforementioned A1754B can be used as filler  18 . Instead, in the case of using PMMA as the material of lens array body  4  and prism  16 , AX4-LS-06 made by NIPPON SHOKUBAI can be used as filler  18 . 
         [0195]    This embodiment can also realize the optical path of monitor light M similar to that described in Embodiment 5, thereby allowing the monitor light to be securely acquired. 
         [0196]    Furthermore, according to this embodiment, laser light L from each light emitting element  7 , having been totally reflected by total reflection surface  4   d , moves forth through the optical path in lens array body  4  and subsequently is incident from first optical surface  14   a  to filler  18  in the front of prism. At this time, filler  18  in the front of prism is formed to have the same refractive index as that of lens array body  4 . Accordingly, laser light L from each light emitting element  7 , having been incident on filler  18  in the front of prism is not refracted, moves forth through the optical path in filler  18  in the front of prism while maintaining linearity to the optical path connecting total reflection surface  4   d  and first optical surface  14   a , and subsequently is incident on reflecting/transmitting layer  17 . Moreover, prism  16  is formed to have the same refractive index as that of filler  18  in the front of prism. Accordingly, laser light L from each light emitting element  7 , having passed through reflecting/transmitting layer  17 , moves forth through the optical path in prism  16  while maintaining linearity to the optical path connecting total reflection surface  4   d  and first optical surface  14   a , and subsequently is incident on filler  18  in the rear of prism via second prism surface  16   b . Here, filler  18  in the rear of prism is formed to have the same refractive index as that of prism  16 . Accordingly, laser light L from each light emitting element  7 , having been incident on filler  18  in the rear of prism, is not refracted and moves forth through the optical path in filler  18  in the rear of prism while maintaining linearity to the optical path connecting total reflection surface  4   d  and first optical surface  14   a . Subsequently, laser light L from each light emitting element  7  is incident on lens array body  4  via second optical surface  14   b . Here, lens array body  4  is formed to have the same refractive index as that of filler  18  in the rear of prism. Accordingly, laser light L from each light emitting element  7 , having been incident on lens array body  4 , is not refracted, and moves forth through the optical path in lens array body  4  toward second lens surface  12  while maintaining linearity to the optical path connecting total reflection surface  4   d  and first optical surface  14   a . Accordingly, as with Embodiment 1, the optical path on the incident side onto first optical surface  14   a  and the optical path on the emitting side from second optical surface  14   b  can be aligned on the same line. 
         [0197]    Furthermore, in this embodiment, first optical surface  14   a  and second optical surface  14   b  have a slight inclining angle. Accordingly, in the case of integrally forming lens array body  4  using a mold, demoldability of lens array body  4  can be secured. 
         [0198]    In  FIG. 22 , the entire right side face of concave part  14  including first optical surface  14   a  has a slight inclining angle. In accordance with this, the right end face of prism  16  (portion extending upwardly from the upper end of first prism surface  16   a ) is contact with the portion extending upwardly from the upper end of first optical surface  14   a  on the right side face of concave part  14  in the state where the right end face of prism  16  has the same inclining angle as that of the right side face of concave part  14 . However, the configuration is not necessarily limited to such a configuration. For instance, the portion upwardly extending from the upper end of first optical surface  14   a  on the right side face of concave part  14  may be formed parallel to left end face  4   b  (inclining angle 0°). In accordance with this, the right end face of prism  16  may be formed parallel to left end face  4   b.    
         [0199]    Likewise, in  FIG. 22 , the entire left side face of concave part  14  including second optical surface  14   b  has a slight inclining angle. In accordance with this, the left end face of prism  16  (portion extending upwardly from the upper end of second prism surface  16   b ) is in contact with the portion extending upwardly from the upper end of second optical surface  14   b  on the left side face of concave part  14 , in the state where the left end face of prism  16  has the same inclining angle as that of the left side face of concave part  14 . However, the configuration is not necessarily limited to such a configuration. For instance, the portion extending upwardly from the upper end of second optical surface  14   b  on the left side face of concave part  14  may be formed parallel to left end face  4   b . In accordance with this, the left end face of prism  16  may also be formed parallel to left end face  4   b.    
       Embodiment 7 
       [0200]    Embodiment 7 of a lens array and an optical module provided therewith according to the present invention will now be described mainly on difference from Embodiment 5 with reference to  FIG. 23 . 
         [0201]    In this embodiment, elements having configurations identical or similar to those in  FIGS. 20 and 21  will be described using the same reference signs. 
         [0202]    As shown in  FIG. 23 , as to lens array  46  and optical module  45  in this embodiment, as with Embodiment 5, first optical surface  14   a  and second optical surface  14   b  are formed parallel to left end face  4   b , and first prism surface  16   a  and second prism surface  16   b  are formed into inclining surfaces. 
         [0203]    However, the configuration of this embodiment is different from that in Embodiment 5, and applicable not only to transmission of optical signals but also to reception of optical signals. 
         [0204]    More specifically, as shown in  FIG. 23 , in this embodiment, laser light having the same wavelength is emitted from end face  5   a  of each optical fiber  5  toward lens array  46 . Accordingly, the laser light emitted from each optical fiber  5  has a wavelength different from that of laser light L emitted from each light emitting element  7 . As more specific means, a plurality of light emitting elements, not shown, equal in number to optical fibers  5  are disposed at the end faces of optical fibers  5  on the side opposite to end faces  5   a  facing lens array  46 , and light emitted from the light emitting elements are incident on respective corresponding optical fibers  5 . 
         [0205]    The laser light having thus emitted from each optical fiber  5  enters respective second lens surfaces  12  corresponding to the optical fibers. 
         [0206]    As shown in  FIG. 23 , in this embodiment, optoelectric converting device  3  includes a plurality of second light receiving elements  47  that are on a surface of semiconductor substrate  6  facing lens array  46  at left adjacent positions of light receiving elements  8  in  FIG. 23  and receive laser light emitted from respective optical fibers  5 . The plurality of second light receiving elements  47  are arranged equal in number and pitch to second lens surfaces  12  along the same direction as the alignment direction of second lens surfaces  12 . Each second light receiving element  47  may be a photo-detector. 
         [0207]    Furthermore, as shown in  FIG. 23 , at positions facing second light receiving elements  47  at bottom face  4   a  (i.e. bottom surface  23   a  of counter-bore part  23 ), a plurality of respective fourth lens surfaces  48  are formed that emit laser light toward second light receiving elements  47  after it has been emitted from optical fibers  5  and incident from the inside of lens array body  4 . The plurality of fourth lens surfaces  48  are provided equal in number and pitch to second lens surfaces  12 , along the same direction as the alignment direction of second lens surfaces  12 . 
         [0208]    Furthermore, as shown in  FIG. 23 , second reflecting/transmitting layer  50  is disposed on second prism surface  16   b.    
         [0209]    Here, laser light having been emitted from each optical fiber  5  and incident on second lens surface  12  is incident on second reflecting/transmitting layer  50 . Second reflecting/transmitting layer  50  reflects the incident laser light at a predetermined reflectance toward fourth lens surfaces  48  side while allowing the light to pass through at a predetermined transmittance. 
         [0210]    According to such a configuration, the laser light emitted from each optical fiber  5  passes through second lens surface  12 , second reflecting/transmitting layer  50  and fourth lens surface  48  and is coupled to second light receiving element  47 . Accordingly, bidirectional optical communication can be effectively supported. 
         [0211]    Second reflecting/transmitting layer  50  may be formed using the same material and method as those of reflecting/transmitting layer  17 . 
         [0212]    In terms of facilitation of design, optical axis OA( 4 ) on fourth lens surface  48  is preferably perpendicular to bottom face  4   a . The configuration for supporting bidirectional communication similar to this embodiment may be applied to the configuration in Embodiment 6. 
       Embodiment 8 
       [0213]    Embodiment 8 of a lens array and an optical module provided therewith according to the present invention will now be described mainly on a configuration specific to this embodiment with reference to  FIGS. 24 to 27 . 
         [0214]    In this embodiment, elements having configurations identical or similar to those in each of the embodiments will be described using the same reference signs. 
         [0215]      FIG. 24  is a configurational diagram schematically showing an overview of optical module  55  in this embodiment together with a longitudinal sectional view of lens array  56  in this embodiment.  FIG. 25  is a plan view of lens array  56  shown in  FIG. 24 .  FIG. 26  is a left side view of lens array  56  shown in  FIG. 24 .  FIG. 27  is a bottom view of lens array  56  shown in  FIG. 24 . 
         [0216]    Here, as shown in  FIG. 24 , lens array  56  and optical module  55  of this embodiment are the same as those in the configuration of Embodiment 4 in  FIG. 18 , in terms of configurations of concave part  14 , prism  16 , reflecting/transmitting layer  17  and filler  18  in concave part  14 . In this embodiment, the left end of flange  36  of prism  16  is formed shorter than that in Embodiment 4, and disposed on filler  18  in concave part  14 . Adoption of such a difference in configuration in Embodiment 4 may be optional. 
         [0217]    As shown in  FIG. 24 , in this embodiment, as with Embodiment 7 shown in  FIG. 23 , optoelectric converting device  3  includes second light receiving elements  47  formed to align along the alignment direction of second lens surface  12  that are on a surface of semiconductor substrate  6  facing lens array  56  at left adjacent positions of light receiving elements  8  in  FIG. 24 . Furthermore, as shown in  FIGS. 24 and 27 , in this embodiment, as with Embodiment 7, the plurality of fourth lens surfaces  48  are formed to align along the alignment direction of second lens surfaces  12  at positions facing second light receiving elements  47  at bottom face  4   a  of lens array  4  (bottom surface  23   a  of counter-bore part  23 ). 
         [0218]    As with Embodiment 7, second light receiving elements  47  and fourth lens surfaces  48  have configurations for supporting reception of optical signals. 
         [0219]    Note that, in this embodiment, optical signals are not received according to a one core bidirectional (BiDi) system, which is adopted in Embodiment 7. As shown in  FIG. 24 , signals are received using second optical fibers  58  dedicated for reception, which are second transmission members. Second optical fibers  58  are arranged in parallel adjacent to optical fibers  5  for transmission (below adjacent in  FIG. 24 ) so that second optical fibers  58  are held in the same connector  10  as optical fibers  5  for transmission. In this embodiment, second optical fibers  58  are provided equal in pitch and number (twelve) to optical fibers  5  for transmission, along the same direction as the alignment direction of optical fibers  5  for transmission. The number of second optical fibers  58  is identical to the number of second light receiving elements  47  and the number of fourth lens surfaces  48 . 
         [0220]    In this embodiment, laser light is emitted from end faces  58   a  of the plurality of second optical fibers  58  facing lens array  56 , toward lens array  56 . The laser light corresponds to a reception optical signal. 
         [0221]    As shown in  FIGS. 24 and 26 , fifth lens surfaces  60 , which are equal in number to second optical fibers  58  and on which light emitted from respective second optical fibers  58  is incident, are provided at positions that are adjacent to second lens surfaces  12  on left end face  4   b  of lens array  4  in the direction orthogonal to the alignment direction of these surfaces  12  (downward direction in  FIG. 24 ) and face end faces  58   a  of second optical fibers  58 . The plurality of fifth lens surfaces  60  are arranged in line at the same pitch as second lens surfaces  12  along the alignment direction of second lens surfaces  12 . Fifth lens surfaces  60  may have the same diameter as that of the second lens surfaces. 
         [0222]    Furthermore, as shown in  FIGS. 24 and 25 , second concave part  61  is formed in a reentrant manner so as to be located at the left of concave part  14  on top face  4   c  of lens array  4  and be located at the left of concave part  14  and so that the optical paths connecting first lens surfaces  11  and second lens surfaces  12  pass through concave part  14 . 
         [0223]    Here, as shown in  FIG. 24 , second concave part  61  has third optical surface  61   a  forming a part of the inner surface (right side face of second concave part  61  in  FIG. 24 ). Third optical surface  61   a  is formed parallel to left end face  4   b.    
         [0224]    As shown in  FIG. 24 , laser light L T  from each light emitting element  7 , having been incident on second optical surface  14   b  of concave part  14  and moved forth toward second lens surfaces  12  side, is perpendicularly incident on third optical surface  61   a  from the right in  FIG. 24 . As shown in  FIG. 24 , second concave part  61  has fourth optical surface  61   b  that is a part of the inner surface and forms a portion opposite to third optical surface  61   a  at the left in  FIG. 24  (left side face of second concave part  61  in  FIG. 24 ). Fourth optical surface  61   b  is formed parallel to left end face  4   b.    
         [0225]    As shown in  FIG. 24  laser light L T  from each light emitting element  7 , having been incident on third optical surface  61   a  and moved forth toward second lens surface  12  side, is perpendicularly incident on fourth optical surface  61   b  from the right in  FIG. 24 . 
         [0226]    Furthermore, as shown in  FIG. 24 , second concave part  61  has second total reflection surface  61   c , which is a part of the inner surface, that is, forms a center portion of the bottom surface of second concave part  61  in  FIG. 24 . Second total reflection surface  61   c  is formed into an inclining surface where the upper end is located to the left of the bottom end in  FIG. 24 . A portion that is at the bottom surface of second concave part  61  and other than second total reflection surface  61   c  is formed parallel to top face  4   c  of lens array body  4 . Second total reflection surface  61   c  may be formed parallel to total reflection surface  4   d  described earlier. 
         [0227]    Laser light L R , having been incident on fifth lens surfaces  60  from second optical fibers  58 , is incident on such second total reflection surface  61   c  from the left in  FIG. 24  at an incident angle of at least the critical angle. Second total reflection surface  61   c  totally reflects laser light L R , having been incident from second optical fibers  58 , toward fourth lens surfaces  48  side (in the downward direction in  FIG. 24 ). 
         [0228]    This configuration allows laser light L R , having been emitted from second optical fibers  58 , to pass through fifth lens surface  60 , second total reflection surface  61   c  and fourth lens surfaces  48  and be coupled to respective second light receiving elements  47 . Accordingly, reception of optical signals can be effectively supported. 
         [0229]    In particular, the configuration of this embodiment is optimal to be applied to the optical communication at 120 Gbps according to CXP standard (see September 2009, Annex A6, InfiniBand architecture specifications Vol. 2 Release 1.2.1) having recently been proposed. 
         [0230]    In this embodiment, as described above, laser light L T  is perpendicularly incident on both third optical surface  61   a  and fourth optical surface  61   b . This does not cause second concave part  61  to refract laser light L T  to change the traveling direction; second concave part  61  is an effective element to form second total reflection surface  61   c  into a shape capable of securing demoldability without increase in the number of components. Accordingly, optical signals can securely be transmitted as well as be received. 
         [0231]    Furthermore, as shown in  FIG. 27 , in this embodiment, fitting holes  24  for positioning optoelectric converting device  3  are formed on bottom face  4   a  of lens array  4 , as with the configuration shown in  FIG. 11 . However, in this embodiment, fitting holes  24  are different from those in  FIG. 11  in that fitting holes  24  are formed such that a pair of fitting holes  24  are disposed across counter-bore part  23 . However, in this embodiment, the means for positioning optoelectric converting device  3  and optical fibers  5  and  58  are not limited to that shown in the diagram. 
         [0232]    Furthermore, as shown in  FIG. 24 , in lens array body  4 , third concave part  63  that has a trapezoidal shape in a sectional view and includes total reflection surface  4   d  as a part of the inner surface is formed. Third concave part  63  has a function of storing filler  18  if filler  18  is spilled out of flange  36  during installation of filler  18  on flange  36  of prism  16 . Accordingly, in this embodiment, advancement of spilling of filler  18  can be suppressed. 
         [0233]    As shown in  FIGS. 25 and 27 , mark  65  for positioning optoelectric converting device  3  may be formed on bottom face  4   a  of lens array body  4  (bottom surface  23   a  of counter-bore part  23 ), and optical means may be utilized to position optoelectric converting device  3 . 
         [0234]    In terms of facilitating design, optical axis OA( 5 ) of fifth lens surface  60  is preferably perpendicular to left end face  4   b.    
         [0235]    Furthermore, as one variation of this embodiment, the configurations of concave part  14 , prism  16 , reflecting/transmitting layer  17  and filler  18  may be replaced with the configuration of Embodiment 4 shown in  FIG. 19 , or any one of Embodiments 1 to 3, 5 and 6. Even in such a case, the configuration specific to this embodiment for also supporting reception of optical signals is not degraded. 
         [0236]    Furthermore, as another variation in this embodiment, as shown in  FIG. 28 , second prism  67  formed so as to have the same refractive index as that of lens array body  4  may be arranged between third optical surface  61   a  and fourth optical surface  61   b  in a space formed by second concave part  61 . Note that second prism  67  is formed into a shape that does not reach second total reflection surface  61   c . Thus, the number of components is increased in comparison with the configuration shown in  FIG. 24 . However, this configuration can effectively suppress Fresnel reflection on third optical surface  61   a  and fourth optical surface  61   b.    
         [0237]    The present invention is not limited to the aforementioned embodiments, and can be modified variously in such an extent that the characteristics of the present invention is not degraded. 
         [0238]    For instance, as shown in  FIG. 29 , second total reflection surface  61   c  for supporting reception of optical signals that has been described in Embodiment 8 may be formed in concave part  14  as a part of the inner surface of concave part  14  without provided in second concave part  61 . 
         [0239]    Lens array body  4  may be formed using light-transmitting material (e.g. glass) other than resin material. 
         [0240]    Furthermore, the present invention is effectively applicable also to an optical transmission member other than optical fiber  5 , such as an optical waveguide. 
       Embodiment 9 
       [0241]    Embodiment 9 of a lens array and an optical module provided therewith according to the present invention will now be described with reference to  FIGS. 30 to 35 . 
         [0242]    In  FIGS. 30 to 35 , components having the same configuration as those of  FIGS. 1 to 29  are assigned with the same reference signs. 
         [0243]      FIG. 30  is a configurational diagram schematically showing an overview of optical module  1  in this embodiment together with a longitudinal sectional view of lens array  2  in this embodiment.  FIG. 31  is a plan view of lens array  2  shown in  FIG. 30 .  FIG. 32  is a left side view of lens array  2  shown in  FIG. 30 .  FIG. 33  is a right side view of lens array  2  shown in  FIG. 30 .  FIG. 34  is a bottom view of lens array  2  shown in  FIG. 30 . 
         [0244]    As shown in  FIG. 30 , lens array  2  in this embodiment is disposed between optoelectric converting device  3  and optical fiber  5 . 
         [0245]    Here, optoelectric converting device  3  includes the plurality of light emitting elements  7  that emit laser light L toward a surface of semiconductor substrate  6  facing lens array  2  in the direction perpendicular to this surface (upper direction in  FIG. 30 ). Light emitting elements  7  constitute a vertical cavity surface emitting laser (VCSEL). In  FIG. 30 , light emitting elements  7  are formed to align along the direction perpendicular to the sheet of  FIG. 30 . Furthermore, optoelectric converting device  3  includes the plurality of light receiving elements  8  that are for receiving monitor light M to monitor an output of laser light L (e.g. intensity and amount of light) emitted from respective light emitting elements  7  and are equal in number to light emitting elements  7 , at left adjacent positions of  FIG. 30  to the respective light emitting elements  7 , on a surface of semiconductor substrate  6  facing lens array  2 . Light receiving elements  8  are arranged in line in the same direction as the direction of light emitting elements  7 . The positions of light emitting elements  7  and light receiving elements  8 , which correspond to each other, in the alignment direction match with each other. That is, light receiving elements  8  are arranged at the same pitch as light emitting elements  7 . Light receiving elements  8  may be photo-detectors. Furthermore, although not shown, optoelectric converting device  3  is connected with a control circuit that controls an output of laser light L emitted from light emitting elements  7  on the basis of the intensity or amount of monitor light M received by light receiving elements  8 . For instance, such optoelectric converting device  3  is disposed opposite to lens array  2  such that a contact part (not shown) with lens array  2  is in contact with lens array  2 . Optoelectric converting device  3  is attached to lens array  2  by publicly known fixation means. 
         [0246]    Optical fibers  5  in this embodiment are provided equal in number to light emitting elements  7  and light receiving elements  8 . Optical fibers  5  are arranged in line along the direction perpendicular to the sheet of  FIG. 30 . Optical fibers  5  are arranged in line at the same pitch as light emitting elements  7 . Each optical fiber  5  is attached to lens array  2  by publicly known fixation means in the state where a part of the fiber on a side of end face  5   a  is held in bulk multicore connector  10 . 
         [0247]    Lens array  2  optically couples light emitting elements  7  and end faces  5   a  of respective optical fibers  5  to each other in the state where lens array  2  is disposed between optoelectric converting device  3  and optical fibers  5 . 
         [0248]    Lens array  2  is further described; as shown in  FIG. 30 , lens array  2  includes lens array body  4 . Lens array body  4  is formed to have a substantially trapezoidal external shape in a longitudinal sectional view, a substantially rectangular shape in a plan view as shown in  FIG. 31 , and a rectangular shape in a side view as shown in  FIGS. 32 and 33 . 
         [0249]    As shown in  FIGS. 30 and 34 , lens array  2  has a plurality of (eight) first lens surfaces (convex lens surfaces)  11  that are plano-convex and equal in number to light emitting elements  7 , on bottom face  4   a  (plane) as a first surface of lens array body  4  in  FIG. 34  facing optoelectric converting device  3 . The plurality of first lens surfaces  11  are formed to align in the predetermined alignment direction (direction perpendicular to the sheet of  FIG. 30 , longitudinal direction in  FIG. 34 ) corresponding to light emitting elements  7 . First lens surfaces  11  are arranged at the same pitch as light emitting elements  7 . Furthermore, as shown in  FIG. 30 , optical axis OA( 1 ) on each first lens surface  11  coincides with the central axis of laser light L emitted from light emitting element  7  corresponding to first lens surface  11 . 
         [0250]    As shown in  FIG. 30 , laser light L emitted from each light emitting element  7  corresponding to first lens surface  11  is incident on first lens surface  11 . Each first lens surface  11  collimates incident laser light L emitted from light emitting element  7 , and causes the collimated light to move forth into lens array body  4 . 
         [0251]    As shown in  FIGS. 30 and 32 , lens array  2  has the plurality of second lens surfaces (convex lens surfaces)  12  equal in number to first lens surfaces  11 , on left end face  4   b  (plane) in  FIG. 30  as a second surface of lens array body  4  facing end faces  5   a  of optical fibers  5 . The plurality of second lens surfaces  12  are formed to align in the same direction as the alignment direction of first lens surfaces  11 . Second lens surfaces  12  are arranged at the same pitch as first lens surfaces  11 . Optical axis OA( 2 ) on each second lens surface  12  is preferably disposed on the same axis as the central axis of end face  5   a  of optical fiber  5  corresponding to second lens surface  12 . 
         [0252]    As shown in  FIG. 30 , laser light L from each light emitting element  7 , having been incident on first lens surface  11  corresponding to second lens surface  12  and moved forth through the optical path in lens array body  4 , is incident on second lens surface  12  in the state where the central axis of the laser light coincides with optical axis OA( 2 ) on second lens surface  12 . Each second lens surface  12  emits incident laser light L from light emitting element  7  toward end face  5   a  of optical fiber  5  corresponding to second lens surface  12 . 
         [0253]    Thus, light emitting elements  7  and respective end faces  5   a  of optical fibers  5  are optically coupled to each other via first lens surfaces  11  and second lens surfaces  12 . 
         [0254]    Furthermore, as shown in  FIGS. 30 and 34 , third lens surfaces  13  equal in number to light receiving elements  8  (also equal in number to light emitting elements  7 , optical fibers  5 , first lens surfaces  11  and second lens surfaces  12  in this embodiment) are formed at left adjacent positions of  FIG. 30  to first lens surfaces  11 , on bottom face  4   a  of lens array body  4 . Third lens surfaces  13  are formed to align in the predetermined alignment direction corresponding to light receiving elements  8 , that is, the same direction as the alignment direction of first lens surfaces  11 . Third lens surfaces  13  are arranged at the same pitch as light receiving elements  8 . Optical axis OA( 3 ) on each third lens surface  13  preferably coincides with the central axis of light receiving surface of light receiving element  8  corresponding to third lens surface  13 . 
         [0255]    As shown in  FIG. 30 , monitor light M from each light emitting element  7  corresponding to third lens surface  13  is incident on third lens surface  13  from the inside of lens array body  4 . Each third lens surface  13  emits incident monitor light M from light emitting element  7  toward light receiving element  8  corresponding to third lens surface  13 . 
         [0256]    Furthermore, as shown in  FIGS. 30 and 33 , lens array body  4  includes total reflection surface  4   d  at the right upper end in  FIG. 30 . Total reflection surface  4   d  is formed into an inclining surface where the upper end is located left to the bottom end in  FIG. 30  (i.e. on a side of after-mentioned concave part  14 ). Total reflection surface  4   d  lies in the optical path of laser light L from each light emitting element  7 , between first lens surface  11  and after-mentioned first optical surface  14   a  of concave part  14 . 
         [0257]    As shown in  FIG. 30 , laser light L from each light emitting element  7 , having been incident on first lens surface  11 , is incident on such total reflection surface  4   d  from the bottom in  FIG. 30  at an incident angle of at least the critical angle. Total reflection surface  4   d  totally reflects incident laser light L from each light emitting element  7  toward the left in  FIG. 30 . 
         [0258]    Note that a reflection film made of Au, Ag, Al or the like may be coated onto total reflection surface  4   d.    
         [0259]    As shown in  FIGS. 30 and 31 , concave part  14  is formed in a reentrant manner so that the optical paths connecting first lens surfaces  11  and second lens surfaces  12  pass through therein, on top face  4   c  (plane) of lens array body  4  in  FIG. 30  as a third surface. Top face  4   c  is formed parallel to bottom face  4   a.    
         [0260]    Here, as shown in  FIG. 30 , concave part  14  has first optical surface  14   a  forming a part of the inner surface (right side face of concave part  14  in  FIG. 30 ). First optical surface  14   a  is formed into an inclining surface having a predetermined inclining angle to left end face  4   b  where the upper end is located right to the bottom end in  FIG. 30  (i.e. on a side of total reflection surface  4   d ). 
         [0261]    As shown in  FIG. 30 , laser light L from each light emitting element  7 , having been totally reflected by total reflection surface  4   d , is incident on such first optical surface  14   a  at a predetermined incident angle. However, the incident direction of laser light L from each light emitting element  7  onto first optical surface  14   a  is perpendicular to left end face  4   b.    
         [0262]    As shown in  FIG. 30 , concave part  14  has second optical surface  14   b , which is a part of the inner surface and opposite to first optical surface  14   a  at the left in  FIG. 30  (left side face of concave part  14  in  FIG. 30 ). Second optical surface  14   b  is formed parallel to left end face  4   b.    
         [0263]    As shown in  FIG. 30 , laser light L from each light emitting element  7 , having been incident on first optical surface  14   a  and subsequently moved forth toward second lens surface  12  side, is incident on such second optical surface  14   b  perpendicularly to second optical surface  14   b . Second optical surface  14   b  allows incident laser light L from each light emitting element  7  to pass perpendicularly to the surface. 
         [0264]    Furthermore, as shown in  FIG. 30 , prism  16  having a trapezoidal longitudinal section is disposed in a space formed by concave part  14 . Prism  16  is formed to have the same refractive index as that of lens array body  4 . Prism  16  may be made of the same material as that of lens array body  4  (e.g. resin material, such as polyetherimide). 
         [0265]    For instance, in the case where lens array body  4  and prism  16  are made of Ultem made by SABIC as a polyetherimide, the refractive indices of lens array body  4  and prism  16  are 1.64 for light with a wavelength of 850 nm. 
         [0266]    Besides that, in the case of forming lens array body  4  and prism  16  using ARTON made by JSR as an annular olefin resin, the refractive index for light with a wavelength of 850 nm is 1.50. 
         [0267]    Here, as shown in  FIG. 30 , prism  16  has first prism surface  16   a  forming a part of the surface thereof (right side face of prism  16  in  FIG. 30 ). First prism surface  16   a  is disposed parallel to first optical surface  14   a  at a position facing first optical surface  14   a  at a predetermined interval from first optical surface  14   a  in the left direction in  FIG. 30 . 
         [0268]    Furthermore, as shown in  FIG. 30 , prism  16  has second prism surface  16   b  forming a part of the surface thereof (left side face of prism  16  in  FIG. 30 ). Second prism surface  16   b  is disposed parallel to second optical surface  14   b  at a position facing second optical surface  14   b  at a predetermined interval from second optical surface  14   b  in the right direction in  FIG. 30 . 
         [0269]    Prism  16  forms the optical path of laser light L from each light emitting element  7 , having been incident on first optical surface  14   a  and subsequently moved forth toward second lens surface  12  side. 
         [0270]    Furthermore, as shown in  FIG. 30 , thin reflecting/transmitting layer  17  having a uniform thickness is disposed on first prism surface  16   a . The surface of reflecting/transmitting layer  17  on the side of first prism surface  16   a  is in closely contact with first prism surface  16   a.    
         [0271]    Moreover, as shown in  FIG. 30 , light-transmitting adhesive sheet  15 , which has a uniform thickness and a predetermined refractive index, is arranged between reflecting/transmitting layer  17  and first optical surface  14   a . The surface of adhesive sheet  15  on the side of reflecting/transmitting layer  17  is in closely contact with reflecting/transmitting layer  17 . The surface of adhesive sheet  15  on the side of first optical surface  14   a  is in closely contact with first optical surface  14   a . Prism  16  is bonded by adhesive sheet  15  to lens array body  4  (more specifically, first optical surface  14   a ) via reflecting/transmitting layer  17 . For instance, adhesive thin (e.g. 20 μm) refractive index matching film, such as Fitwell manufactured by Tomoegawa, can be used as adhesive sheet  15 . 
         [0272]    Here, as shown in  FIG. 30 , laser light L from each light emitting element  7 , having been incident on first optical surface  14   a , passes through adhesive sheet  15  and subsequently is incident on reflecting/transmitting layer  17 . Reflecting/transmitting layer  17  reflects incident laser light L from each light emitting element  7  toward third lens surface  13  side at a predetermined reflectance, and allows the light to pass through toward prism  16  side at a predetermined transmittance. 
         [0273]    Here, as shown in  FIG. 30 , reflecting/transmitting layer  17  reflects a part of laser light L from each light emitting element  7  (light of the amount of reflectance), having been incident on reflecting/transmitting layer  17 , as monitor light M from each light emitting element  7  that corresponds to each light emitting element  7 , toward third lens surface  13  side corresponding to monitor light M. 
         [0274]    Monitor light M from each light emitting element  7  thus reflected by reflecting/transmitting layer  17  moves forth in lens array body  4  toward third lens surface  13  side and is subsequently emitted from third lens surface  13  toward corresponding light receiving element  8 . 
         [0275]    Here, for instance, in the case of coating first prism surface  16   a  with a single layer film of Cr using a publicly known coating technique to form reflecting/transmitting layer  17 , reflectance of reflecting/transmitting layer  17  can be 30% and transmittance can be 30% (absorptance of 40%). Reflecting/transmitting layer  17  may be formed using a single metal single layer film of Ni, Al or the like, which is other than Cr. In the case of coating first prism surface  16   a  with a publicly known dielectric multilayer film of Tiθ 2 , Siθ 2  or the like using a publicly known coating technique to form reflecting/transmitting layer  17 , for instance, reflectance of reflecting/transmitting layer  17  can be 20% and transmittance can be 80%. Instead, reflectance and transmittance of reflecting/transmitting layer  17  can be set to desired values in accordance with the material, thickness and the like of reflecting/transmitting layer  17  within a limit where an amount of monitor light M that is considered sufficient for monitoring the output of laser light L can be acquired. Reflecting/transmitting layer  17  can be coated using a coating technique, such as Inconel deposition. Furthermore, for instance, reflecting/transmitting layer  17  may be made of a glass filter. 
         [0276]    On the other hand, laser light L from each light emitting element  7 , having passed through reflecting/transmitting layer  17 , is incident on first prism surface  16   a  immediate after the transmission. Laser light L from each light emitting element  7 , having been incident on first prism surface  16   a , moves forth through the optical path in prism  16  toward second lens surface  12  side. 
         [0277]    At this time, prism  16  is formed to have the same refractive index as that of lens array body  4 , thereby allowing the optical path of laser light L from each light emitting element  7  in prism  16  to be maintained parallel to the optical path of laser light L connecting total reflection surface  4   d  and first optical surface  14   a.    
         [0278]    This will be described in detail. Provided that first optical surface  14   a , the interface between adhesive sheet  15  and reflecting/transmitting layer  17 , and first prism surface  16   a  are parallel to each other, following Equations 1 and 2 hold. 
         [0279]    (Snell&#39;s Law at First Optical Surface) 
         [0000]      n 1  sin θ 1 =n 2  sin θ 2   (Equation 1)
 
         [0280]    (Snell&#39;s Law at First Prism Surface) 
         [0000]      n 2  sin θ 2 =n 1  sin θ 3   (Equation 2)
 
         [0281]    Note that, in Equations 1 and 2, n 1  represents the refractive index of lens array body  4  and prism  16 , and n 2  represents refractive index of adhesive sheet  15 . These n 1  and n 2  are acquired with reference to light having the same wavelength. θ 1  in Equation 1 represents the incident angle of laser light L from each light emitting element  7  onto first optical surface  14   a. θ   2  in Equations 1 and 2 represents the emission angle from first optical surface  14   a  concerning laser light L from each light emitting element  7 , and the incident angle of laser light L from each light emitting element  7  onto first prism surface  16   a , respectively. Note that, the refraction of laser light L at reflecting/transmitting layer  17  is neglected here, because the thickness of reflecting/transmitting layer  17  (measurement in the optical path direction) is significantly thin in comparison with lens array body  4 , adhesive sheet  15  and prism  16 . θ 3  in Equation 2 represents the emission angle from first prism surface  16   a  concerning laser light L from each light emitting element  7 . The plane normal direction of first optical surface  14   a  is adopted as the references (0°) of θ 1  to θ 3 . 
         [0282]    Because the right side of Equation 1 and the left side of Equation 2 are identical to each other, the following equation is derived. 
         [0000]      n 1  sin θ 1 =n 1  sin θ 3   (Equation 3)
 
         [0283]    According to Equation 3, θ 3 =θ 1 . This represents that the optical path of laser light L from each light emitting element  7  in prism  16  is parallel to the optical path of laser light L connecting total reflection surface  4   d  and first optical surface  14   a.    
         [0284]    Thus, laser light L from each light emitting element  7 , having moved forth through the optical path in prism  16 , is perpendicularly incident on second prism surface  16   b  as shown in  FIG. 30  and emitted from second lens surface  16   b  to the outside of prism  16  perpendicularly to second lens surface  16   b , while parallelity to the optical path of laser light L connecting total reflection surface  4   d  and first optical surface  14   a  is maintained. 
         [0285]    As shown in  FIG. 30 , lens array body  4  includes filler  18  that has a predetermined refractive index and is inserted between second optical surface  14   b  and second prism surface  16   b . Here, as shown in  FIG. 30 , laser light L from each light emitting element  7 , having been emitted from second prism surface  16   b , is incident on surface (hereinafter, referred to as incident side surface)  18   a  of filler  18  on the side of second prism surface  16   b  perpendicularly to incident side surface  18   a  immediate after the emission. Laser light L from each light emitting element  7 , having been incident on incident side surface  18   a , moves forth through the optical path in filler  18  toward second lens surface  12  side. Further, laser light L from each light emitting element  7 , having moved forth through the optical path in filler  18 , is perpendicularly incident on surface (hereinafter, referred to as emitting side surface)  18   b  of filler  18  on the side of second optical surface  14   b , and emitted from emitting side surface  18   b  to the outside of filler  18  perpendicularly to emitting side surface  18   b.    
         [0286]    Laser light L from each light emitting element  7 , having thus perpendicularly emitted from filler  18 , is perpendicularly incident on second optical surface  14   b  immediately after emission as described above. Laser light L from each light emitting element  7 , having been incident on second optical surface  14   b , moves forth through the optical path in lens array body  4  after second optical surface  14   b  toward each second lens surface  12  side and is subsequently emitted by second lens surface  12  toward end face  5   a  of corresponding optical fiber  5 . 
         [0287]    The aforementioned configuration allows reflecting/transmitting layer  17  between adhesive sheet  15  and first prism surface  16   a  to split laser light L from each light emitting element  7 , having been incident on first lens surface  11 , toward second lens surface  12  side and third lens surface  13  side. Monitor light M split toward third lens surface  13  side can be emitted by each third lens surface  13  toward light receiving element  8  side. As a result, monitor light M can be securely acquired. Adoption of reflecting/transmitting layer  17  capable of being easily formed to have a certain extent of area, as a configuration of acquiring such monitor light M, facilitates manufacturing of lens array  2 . 
         [0288]    According to this embodiment, prism  16  is formed to have the same refractive index as that of lens array body  4 , thereby allowing the optical path of laser light L from each light emitting element  7  in prism  16  to be maintained perpendicular to left end face  4   b . Furthermore, laser light L from each light emitting element  7 , having thus moved forth through the optical path in prism  16 , can sequentially be incident perpendicularly to second prism surface  16   b  and second optical surface  14   b . This allows the optical path of laser light L from each light emitting element  7  in lens array body  4  to be parallel to each other between an incident side onto first optical surface  14   a  (between total reflection surface  4   d  and first optical surface  14   a  in  FIG. 30 ) and an emitting side from second optical surface  14   b . As a result, for instance, in the case of product inspection, this can reduce the number of spots required to be adjusted in measurements (modification of a mold shape etc.) for canceling a deviation from the center of each second lens surface  12  concerning laser light L, which has been from each light emitting element  7  and incident on each second lens surface  12 , if such a deviation is confirmed. More specifically, in the case of a configuration incapable of securing parallelity between the optical path on the incident side onto first optical surface  14   a  and the optical path on the emitting side from second optical surface  14   b , the measurements of optical surfaces  14   a  and  14   b  of concave part  14  and prism surfaces  16   a  and  16   b  of prism  16  (including the inclining angle) are sometimes required to be adjusted within a permissible limit for correcting the axial deviation of incident light on second lens surface  12 . 
         [0289]    In contrast, according to this embodiment, if accuracy in measuring is secured such that the total reflection direction at total reflection surface  4   d  is perpendicular to left end face  4   b  and further second optical surface  14   b  and second prism surface  16   b  are parallel to left end face  4   b , complicated measurement adjustment to reset optimal inclining angles relative to respective surfaces  14   a ,  14   b ,  16   a  and  16   b  is not required. This can contribute to further facilitation of manufacturing lens array  2 . 
         [0290]    Furthermore, according to this embodiment, second optical surface  14   b  is formed parallel to left end face  4   b , thereby allowing design of second optical surface  14   b  and determination of accuracy in measuring thereof to be simplified. 
         [0291]    Moreover, according to this embodiment, filler  18  is inserted between second optical surface  14   b  and second prism surface  16   b . Accordingly, in this embodiment, even if a scratch is formed on second optical surface  14   b , reflection or scattering of laser light L on second optical surface  14   b  caused by the scratch can be suppressed. The effect of suppressing reflected/scattered light owing to filler  18  is based on the same principle as a principle that drops of water applied onto a surface of frosted glass cover irregularities thereat and the frosted glass becomes transparent. Here, reflection and scattering of laser light L cause occurrence of stray light or reduction in coupling efficiency of laser light L with fiber end  5   a . Accordingly, suppression of reflection and scattering of laser light L is significantly important in terms of securing optical performance. In particular, such an effect of suppressing reflected/scattered light is effective in the case where lens array body  4  is integrally molded by injection molding of resin material (polyetherimide, etc.) using a mold. More specifically, in the case of forming lens array body  4  by injection molding, a molded piece having a shape transferred from concave part  14  is demolded. According to this embodiment, as described above, in terms of simplifying design and determination of accuracy in measuring, second optical surface  14   b  is formed parallel to left end face  4   b  (i.e. perpendicular to top face  4   c ). In demolding, the piece is demolded by relatively moving in the upper direction in  FIG. 30  such that the mold slides in the direction of the surface of second optical surface  14   b . In this case, second optical surface  14   b  is susceptible to damage. Accordingly, with the configuration of second optical surface  14   b  having high frequency of occurrence of a scratch, it is significantly important to provide filler  18  that avoids malfunction on optical performance due to the scratch. As a result, according to this embodiment, manufacturing and handling (e.g. determination of accuracy in measuring) are facilitated by forming second optical surface  14   b  parallel to left end face  4   b , as well as occurrence of stray light and reduction in coupling efficiency is suppressed (i.e. optical performance is secured) by suppressing reflected/scattered light on second optical surface  14   b.    
         [0292]    Furthermore, as described above, coating of first prism surface  16   a  with the single metal single layer film or the dielectric multilayer film to form reflecting/transmitting layer  17  allows the configuration of reflecting/transmitting layer  17  to be simplified, thereby enabling further facilitation of manufacturing to be realized. Moreover, the coating allows reflecting/transmitting layer  17  to be formed significantly thinly (e.g. 1 μm or less). Accordingly, a lateral deviation of laser light L (shift amount in the longitudinal direction in  FIG. 30 ) caused by the refraction on transmission of laser light L from each light emitting element  7  through reflecting/transmitting layer  17  can be reduced to a negligible level. This allows the optical path on the incident side onto first optical surface  14   a  and the optical path on the emitting side from second optical surface  14   b  to be brought closely to the same line. Accordingly, the position of second lens surface  12  can be simply determined when being designed, thereby contributing to further facilitation of manufacturing. 
         [0293]    Furthermore, preferably, adhesive sheet  15  is configured such that difference of refractive indices with lens array body  4  is 0.35 or less (more preferably, 0). This configuration can suppress the refraction when laser light L from each light emitting element  7  passes through adhesive sheet  15 . Accordingly, the lateral deviation of laser light L when laser light L passes through adhesive sheet  15  can be suppressed. It is a matter of course that if the difference of refractive index is 0, the refraction is not caused at all. This enables optical path on the incident side onto first optical surface  14   a  and the optical path on the emitting side from second optical surface  14   b  to be aligned on the substantially same line. Accordingly, the position of second lens surface  12  can be simply determined when being designed, thereby contributing to further facilitation of manufacturing. 
         [0294]    Furthermore, light-transmitting adhesive may be adopted as filler  18 , and prism  16  may be bonded to lens array body  4  with filler  18 . This allows prism  16  and lens array body  4  to be fixed to each other more firmly in comparison with the case of adhesion only with adhesive sheet  15 , thereby mechanical strength, such as impact resistance, to be improved. Filler  18  may also function as adhesive for bonding prism  16  to lens array body  4 . As a result, the cost can be reduced. For instance, thermoset resin or ultraviolet-set resin may be adopted as such filler  18  that also functions as light-transmitting adhesive. 
         [0295]    Moreover, preferably, the difference of refractive indices between filler  18  and lens array body  4  is a predetermined value of 0.35 or less (more preferably, 0). According to this configuration, Fresnel reflection at the interface between second prism surface  16   b  and filler  18  and Fresnel reflection at the interface between filler  18  and second optical surface  14   b  can be suppressed, thereby occurrence of stray light and reduction in coupling efficiency to be suppressed more securely. In the case of forming lens array body  4  using the aforementioned Ultem made by SABIC, for instance LPC1101 made by Mitsubishi Gas Chemical Company can be used as filler  18 . As to this product, the refractive index of light with wavelength of 850 nm, which is calculated on the basis of the refractive index and Abbe number for d line and disclosed by the manufacturer, is 1.66. In this case, the difference of refractive indices between filler  18  and lens array body  4  is 0.02 (reference of λ=850 nm). Besides that, in the case of forming lens array body  4  using the aforementioned ARTON made by JSR, suitable filler  18  may be A1754B made by TECS, which is UV-curable resin. The refractive index of this product for light with a wavelength of 850 nm is 1.50. In this case, the difference of refractive indices between lens array body  4  and filler  18  is 0. 
         [0296]    Furthermore, preferably, the inclining angle of total reflection surface  4   d  is within a range from 40° to 50° (more preferably, 45°) in the clockwise direction in  FIG. 30  with reference to bottom face  4   a (0°); the inclining angle of first optical surface  14   a  is within a range from 40° to 50° (more preferably, 45°) in the counterclockwise direction in  FIG. 30  with reference to bottom face  4   a (0°). This configuration allows a reasonable design for totally reflecting incident laser light L from each light emitting element  7  on total reflection surface  4   d  toward concave part  14  side and for splitting laser light L incident on first optical surface  14   a  toward second lens surface  12  side and third lens surface  13  side. In particular, in the case where the inclining angles of total reflection surface  4   d  and first optical surface  14   a  are 45°, the design of surfaces  4   d  and  14   a  and determination of accuracy in measuring thereof are more simplified. 
         [0297]    Furthermore, bottom face  4   a  and left end face  4   b  may be formed perpendicular to each other. Optical axis OA( 1 ) on first lens surface  11  and optical axis OA( 3 ) on third lens surface  13  may be formed perpendicular to bottom face  4   a . Optical axis OA( 2 ) on second lens surface  12  may be formed perpendicular to left end face  4   b . This configuration can relax accuracy in measuring that is required for lens array  2  to secure the optical path connecting light emitting element  7  and light receiving element  8  and the optical path connecting light emitting element  7  and end face  5   a  of optical fiber  5 , thereby allowing further facilitation of manufacturing to be realized. More specifically, for instance, in the case where optical axis OA( 3 ) on third lens surface  13  is configured to be inclined at an acute angle to optical axis OA( 1 ) on first lens surface  11 , there is a possibility that a slight measurement error in the longitudinal direction in  FIG. 30  prevents monitor light M, having been emitted from third lens surface  13 , from being coupled to light receiving element  8 . In contrast, as with this embodiment, optical axis OA( 1 ) on first lens surface  11  and optical axis OA( 3 ) on third lens surface  13  are parallel to each other. By this means, even if lens array  2  causes a slight measurement error in the longitudinal direction in  FIG. 30 , the beam diameter of monitor light M emitted from third lens surface  13  merely becomes larger or smaller with respect to a designed value, thus allowing the monitor light M to be appropriately received by each light receiving element  8 . If optical axis OA( 2 ) on second lens surface  12  has an angle other than the right angle to optical axis OA( 1 ) on first lens surface  11 , there is a possibility that a slight measurement error in the lateral direction in  FIG. 30  prevents laser light L, having been emitted from second lens surface  12  from being coupled to the end face of optical fiber  5 . In contrast, as with this embodiment, optical axis OA( 1 ) on first lens surface  11  and optical axis OA( 2 ) on second lens surface  12  are formed to be perpendicular to each other. Accordingly, even if lens array  2  causes a slight measurement error in the lateral direction in  FIG. 30 , the beam diameter of laser light L emitted from second lens surface  12  merely becomes slightly larger or smaller with respect to a designed value, thus allowing the laser light L to be appropriately coupled to the end face of optical fiber  5 . 
         [0298]    In addition to the configuration, in this embodiment, as shown in  FIGS. 30 and 31 , concave part  14  is formed into a shape accommodating bottom surface (bottom face in  FIG. 30 )  14   e  and all sides  14   a  to  14   d  within a range indicated by the external shape of opening  14   f  of concave part  14  in the case of being viewed in the plane normal direction of top face  4   c  (from the top in  FIG. 30 ). In other words, concave part  14  is formed so as to accommodate projected surfaces of bottom surface  14   e  and all sides  14   a  to  14   d  in the plane normal direction of top face  4   c  within the range indicated by the external shape of opening  14   f . As shown in  FIG. 31 , opening  14   f  is formed into a rectangular shape elongated in the longitudinal direction in  FIG. 31  and encompassed therearound by top face  4   c . Sides  14   b  to  14   d  other than first optical surface  14   a  are formed perpendicular to top face  4   c . This configuration allows concave part  14  to be formed into a shape capable of securing demoldability from the mold. This can realize effective manufacturing of lens array  2  using the mold. 
         [0299]    Third lens surfaces  13  and light receiving elements  8  corresponding thereto are not necessarily provided so as to be equal in number to light emitting elements  7 . It is sufficient that at least one set is provided. In this case, at reflecting/transmitting layer  17 , in laser light L from each light emitting element  7  incident on each first lens surface  11 , only a part of laser light L to which third lens surfaces  13  correspond is reflected as monitor light M. The other part of laser light L is reflected but is not used as monitor light M. 
         [0300]    In the configuration in  FIG. 30 , top face  16   c  of prism  16  is at the same plane as top face  4   c  of lens array  4 , and bottom face  16   d  of prism  16  is in contact with bottom surface  14   e  of concave part  14 . However, as shown in  FIG. 35 , even if prism  16  is bonded in the state where top face  16   c  of prism  16  protrudes upward from top face  4   c  of lens array  4 , optical performance is not affected. 
         [0301]    A counter-bore part having a bottom surface parallel to bottom face  4   a  may be provided with a dent in a portion on bottom face  4   a  facing optoelectric converting device  3 . First lens surfaces  11  and third lens surfaces  13  may be formed on the bottom surface (to be a first surface) of the counter-bore part. In this case, optoelectric converting device  3  is fixed to lens array  2  in the state where semiconductor substrate  6  is in contact with the inner circumference of the counter-bore part at bottom face  4   a.    
       Embodiment 10 
       [0302]    Embodiment 10 of a lens array and an optical module provided therewith according to the present invention will now be described mainly on difference from Embodiment 9 with reference to  FIGS. 36 to 41 . 
         [0303]    In this embodiment, elements having configurations identical or similar to those in  FIGS. 30 to 35  will be described using the same reference signs. 
         [0304]      FIG. 36  is a configurational diagram schematically showing an overview of optical module  21  in this embodiment together with a longitudinal sectional view of lens array  22  in this embodiment.  FIG. 37  is a plan view of lens array  22  shown in  FIG. 36 .  FIG. 38  is a left side view of  FIG. 37 .  FIG. 39  is a right side view of  FIG. 37 .  FIG. 40  is a bottom view of  FIG. 37 . 
         [0305]    In this embodiment, as a difference from Embodiment 9, means is adopted for mechanically positioning optoelectric converting device  3  and optical fibers  5  when fixing optoelectric converting device  3  and optical fibers  5  to lens array  22 . 
         [0306]    More specifically, as shown in  FIGS. 36 and 40 , in this embodiment, first lens surfaces  11  and second lens surfaces  12  are formed on bottom surface  23   a  of first counter-bore part  23  (first surface in this embodiment) provided with a dent in bottom face  4   a  of lens array body  4 . Bottom surface  23   a  of first counter-bore part  23  is formed parallel to bottom face  4   a . As shown in  FIG. 40 , first counter-bore part  23  is formed to have such a width that in the longitudinal direction in  FIG. 40  (hereinafter, referred to as the lens alignment direction) that the widthwise edges of first counter-bore part  23  are disposed slightly outwardly from lens surfaces  11  and  13  that are arranged outermost in the lens alignment direction. In this embodiment, lens array body  4  is formed wider in the lens alignment direction than the width of first counter-bore part  23  in the lens alignment direction. In accordance with this, as shown in  FIG. 40 , bottom face  4   a  includes portions that extend outwardly in the lens alignment direction from both ends of first counter-bore part  23 . As shown in  FIG. 40 , at the both extended portions of bottom face  4   a  extending outwardly in the lens alignment direction from both ends of first counter-bore part  23 , two pairs, four in total, of plano-convex fitting holes  24  are formed so as to be disposed across first counter-bore part  23  as a structure for positioning optoelectric converting device  3 . Fitting holes  24  are fitted with fitting pins, not shown, penetrating through semiconductor substrate  6  in the state where semiconductor substrate  6  is in contact with extended portions of bottom face  4   a . This allows optoelectric converting device  3  to be mechanically positioned when optoelectric converting device  3  is fixed to lens array  22 . 
         [0307]    As shown in  FIGS. 36 and 38 , in this embodiment, second lens surfaces  12  are formed on bottom surface  26   a  (second surface in this embodiment) of second counter-bore part  26  provided with a dent in left end face  4   b  of lens array  22 . Bottom surface  26   a  of second counter-bore part  26  is formed parallel to left end face  4   b . As shown in  FIG. 38 , second counter-bore part  26  is formed to have such a width in lens alignment direction that the widthwise edges of second counter-bore part  26  are disposed slightly outwardly from lens surfaces  12  arranged outermost in the lens alignment direction. As shown in  FIG. 38 , in this embodiment, left end face  4   b  includes portions that extend outwardly in the lens alignment direction from both ends of second counter-bore part  26 . As shown in  FIG. 38 , at the both extended portions of left end face  4   b , a pair, two in total, of fitting pins  27  are formed so as to be disposed across second counter-bore part  26  in a protruding manner as a structure for positioning optical fibers  5 . Fitting pins  27  are fitted into fitting holes, not shown, formed in connector  10  in the state where connector  10  is in contact with the extended portions of left end face  4   b . This allows optical fibers  5  to be mechanically positioned when optical fibers  5  are fixed to lens array  22 . 
         [0308]    As shown in  FIG. 36 , in this embodiment, as to a difference from Embodiment 9, concave part  14  is formed to extend upwardly from first optical surface  14   a  and second optical surface  14   b . In accordance with this, the upper end of lens array body  4  is located upwardly from top face  16   c  of prism  16 . 
         [0309]    In  FIG. 36 , the upper end of lens array body  4  is a plane, or top face  4   c , at the left of concave part  14 . The upper end of lens array body  4  forms a ridge line at the right of concave part  14  by intersection of a portion extending upwardly from first optical surface  14   a  of the inner surface of concave part  14  and an extension of total reflection surface  4   d.    
         [0310]    Furthermore, as shown in  FIG. 36 , in this embodiment, filler  18  fills not only a space between second prism surface  16   b  and second optical surface  14   b  but also a space over top face  16   c  of prism  16  so as to fill a step between the upper end of lens array body  4  and top face  16   c  of prism  16 . 
         [0311]    The configuration of this embodiment can also exert excellent working-effect similar to those of Embodiment 9. Furthermore, in this embodiment, optoelectric converting device  3  and optical fibers  5  can be simply positioned with respect to lens array  22  using fitting holes  24  and fitting pins  27 . This allows optoelectric converting device  3  and optical fibers  5  to be simply fixed to lens array  22 . Moreover, in this embodiment, the amount of filler  18  is larger and the adhesive area between prism  16  and concave part  14  is increased in comparison with Embodiment 9. This allows prism  16  to be bonded further firmly to lens array body  14 . 
         [0312]    Instead of aforementioned fitting hole  24 , a through hole having the same diameter as that of fitting hole  24  penetrating lens array body  4  may be formed. The structures for positioning optical fiber  5  may be fitting holes or through holes on the side of lens array body  4 , and fitting pins on the side of optical fiber  5 . Likewise, the structure for positioning optoelectric converting device  3  may be fitting pins on the side of lens array body  4 , and fitting holes or through holes on the side of optoelectric converting device  3 . The positioning of optical fiber  5  and optoelectric converting device  3  is not limited to mechanical positioning. Instead, for instance, the positioning may be performed according to an optical method by optically recognizing a mark formed on lens array body  4 . 
         [0313]    (Variation) 
         [0314]    Next,  FIG. 41  shows a variation of this embodiment. Lens array  22  in this variation extends upwardly from top face  16   c  of prism  16  only at left side face of the array in  FIG. 41  including second optical surface  14   b  among the sides of concave part  14 . The other portions are formed to the same height as top face  16   c  of prism  16 . In this variation, filler  18  fills not only a space between second prism surface  16   b  and second optical surface  14   b  but also the space in a manner flowing upwardly therefrom such that filler  18  fills the space up to the extension upward from second optical surface  14   b  on the left side face of concave part  14  and a predetermined range at the left end side of top face  16   c  of prism  16 . 
       Embodiment 11 
       [0315]    Embodiment 11 of a lens array and an optical module provided therewith according to the present invention will now be described mainly on difference from Embodiments 9 and 10 with reference to  FIGS. 42 to 46 . 
         [0316]    In this embodiment, elements having configurations identical or similar to those in  FIGS. 30 to 41  will be described using the same reference signs. 
         [0317]      FIG. 42  is a configurational diagram schematically showing an overview of optical module  30  in this embodiment together with a longitudinal sectional view of lens array  31  in this embodiment.  FIG. 43  is a plan view of lens array  31  shown in  FIG. 42 .  FIG. 44  is a right side view of  FIG. 43 . 
         [0318]    As shown in  FIG. 42 , the configuration in this embodiment is similar to that in Embodiment 10 in that the side surface of concave part  14  extends upwardly from first optical surface  14   a  and second optical surface  14   b , and filler  18  fills a space in a manner flowing upwardly from top face  16   c  of prism  16 . 
         [0319]    However, this embodiment is different from Embodiment 10 in that concave part  14  has a characteristic surface shape in a part of the inner surface thereof to assist installation of prism  16  into concave part  14 . More specifically, as shown in  FIG. 42 , in this embodiment, bottom surface  14   e  of concave part  14  has a two-step structure. The portion located to the left of prism  16  at bottom surface  14   e  of concave part  14  in  FIG. 42  protrudes upwardly from the remaining portions (a portion in contact with bottom face  16   d  of prism  16 ) on bottom surface  14   e  of concave part  14 . The measurements of the remaining portions of bottom surface  14   e  in the lateral direction in  FIG. 42  match with the measurements of bottom face  16   d  of prism  16  in the same direction. 
         [0320]    Bottom surface  14   e  of concave part  14  having such two-step structure regulates backlash of prism  16  in the lateral direction in  FIG. 42  in the case where prism  16  is installed in concave part  14  while securing a filling space with filler  18  by means of the step of bottom surface  14   e . This allows bottom surface  14   e  of concave part  14  to assist installation of prism  16  into concave part  14 . 
         [0321]    Accordingly, this embodiment can exert excellent working-effects of Embodiment 9, facilitate installation of prism  16  when prism  16  is bonded to concave part  14 , and exert further significant effects that can further facilitate manufacturing of lens array  31 . 
         [0322]    (First Variation) 
         [0323]    Next,  FIG. 45  shows a first variation of this embodiment. Lens array  31  in this variation has a configuration where bottom surface  14   e  of concave part  14  of lens array  22  in Embodiment 10 shown in  FIGS. 36 to 40  is formed into the two-step structure as with  FIG. 42 . 
         [0324]    Lens array  31  in this variation also allows bottom surface  14   e  of concave part  14  to regulate the backlash of prism  16  in the lateral direction in  FIG. 45  by means of the step of bottom surface  14   e  when prism  16  is installed in concave part  14  while securing the filling space with filler  18 , as with lens array  31  shown in  FIGS. 42 to 44 . This allows bottom surface  14   e  of concave part  14  to assist installation of prism  16  into concave part  14 . 
         [0325]    (Second Variation) 
         [0326]    Next,  FIG. 46  shows a second variation of this embodiment. Lens array  31  in this variation has a configuration shown in  FIG. 42  or  45  wherein the measurements of bottom surface  16   d  of prism  16  in the lateral direction in  FIG. 46  are larger than those of the portions at the lower step of the two-step structure of bottom surface  14   e  of concave part  14  in the same direction. Accordingly, a space can intentionally be formed between bottom surface  16   d  of prism  16  and the portions at the lower step of bottom surface  14   e  of concave part  14 . Therefore, according to lens array  31  in this variation, as shown in  FIG. 46 , filler  18  can fill even a space between bottom surface  16   d  of prism  16  and the portions at the lower step of bottom surface  14   e  of concave part  14 , thereby allowing prism  16  to be fixed further firmly to lens array body  4 . Lens array  31  in this variation allows lens array body  4  to support prism  16  via first optical surface  14   a  and the steps of bottom surface  14   e  such that prism  16  is laterally sandwiched. This enables prism  16  to be stably disposed in concave part  14 , and allows an operation of fixing prism  16  using filler  18  to be facilitated. 
         [0327]    The present invention is not limited to the aforementioned embodiments, and can be modified variously in such an extent that the characteristics of the present invention is not degraded. 
         [0328]    For instance, formation of reflecting/transmitting layer  17  on first prism surface  16   a  as described above is convenient for integral molding of lens array body  4  using resin material. Under some concepts, reflecting/transmitting layer  17  may be formed on first optical surface  14   a  by coating or the like, as shown in  FIG. 47 . In this case, as shown in  FIG. 47 , adhesive sheet  15  is arranged between first prism surface  16   a  and reflecting/transmitting layer  17  on first optical surface  14   a . The adhesive force of adhesive sheet  15  allows prism  16  to be bonded to lens array body  4  via first prism surface  16   a . Also in such a case, as with Embodiments 9 to 11, on the optical path of laser light L from each light emitting element  7  in lens array body  4 , the incident side onto first optical surface  14   a  and the emitting side from second optical surface  14   b  can be parallel to each other. 
         [0329]    The present invention is applicable to an optical module capable of bidirectional communication. In this case, the configuration may further include optical fibers for receiving optical signals. Moreover, lens surfaces for receiving optical signals are formed at lens array body  4 , and optoelectric converting device  3  may further include light receiving elements for receiving optical signals. 
         [0330]    Furthermore, lens array body  4  may be formed using light-transmitting material (e.g. glass) other than resin material. 
         [0331]    The present invention is effectively applicable also to optical transmission members other than optical fibers  5 , such as sheet-shaped optical waveguides. 
       Embodiment 12 
       [0332]    Embodiment 12 of a lens array and an optical module provided therewith according to the present invention will now be described with reference to  FIGS. 48 to 57 . In this embodiment, elements having configurations identical to those in  FIGS. 1 to 47  will be described using the same reference signs. 
         [0333]      FIG. 48  is a configurational diagram schematically showing an overview of optical module  1  in this embodiment together with a longitudinal sectional view of lens array  2  in this embodiment.  FIG. 49  is a plan view of lens array  2  shown in  FIG. 48 .  FIG. 50  is a left side view of lens array  2  shown in  FIG. 48 .  FIG. 52  is a right side view of lens array  2  shown in  FIG. 48 .  FIG. 53  is a bottom view of lens array  2  shown in  FIG. 48 . 
         [0334]    As shown in  FIG. 48 , lens array  2  in this embodiment is disposed between optoelectric converting device  3  and optical fiber  5 . 
         [0335]    Here, optoelectric converting device  3  includes the plurality of light emitting elements  7  that emit laser light L having the same wavelength toward a surface of semiconductor substrate  6  facing lens array  2  in the direction perpendicular to this surface (upper direction in  FIG. 48 ). Light emitting elements  7  constitute a vertical cavity surface emitting laser (VCSEL). In  FIG. 48 , light emitting elements  7  are arranged in line along the direction perpendicular to the sheet of  FIG. 48 . Furthermore, optoelectric converting device  3  includes a plurality of first light receiving elements  8  that are equal in number to light emitting elements  7  and receive monitor light M to monitor an output of laser light L (e.g. intensity and amount of light) emitted from respective light emitting elements  7 , at left adjacent positions of  FIG. 48  to the respective light emitting elements  7 , on a surface of semiconductor substrate  6  facing lens array  2 . First light receiving elements  8  are arranged in line in the same direction as the direction of light emitting elements  7 . The positions of light emitting elements  7  and light receiving elements  8 , which correspond to each other, in the alignment direction match with each other. That is, first light receiving elements  8  are arranged at the same pitch as light emitting elements  7 . First light receiving elements  8  may be photo-detectors. Furthermore, although not shown, optoelectric converting device  3  is connected with a control circuit that controls an output of laser light L emitted from light emitting elements  7  on the basis of the intensity or amount of monitor light M received by first light receiving elements  8 . For instance, such optoelectric converting device  3  is disposed opposite to lens array  2  such that a contact part (not shown) with lens array  2  is in contact with lens array  2 . Optoelectric converting device  3  is attached to lens array  2  by publicly known fixation means. 
         [0336]    Optical fibers  5  in this embodiment are provided equal in number to light emitting element  7  and first light receiving elements  8 . In  FIG. 48 , each optical fiber  5  is arranged in line along the direction perpendicular to the sheet of  FIG. 48 . Optical fibers  5  are arranged in line at the same pitch as light emitting elements  7 . Each optical fiber  5  is attached to lens array  2  by publicly known fixation means in the state where a portion of the fiber on a side of end face  5   a  is held in bulk multicore connector  10 . 
         [0337]    Lens array  2  optically couples light emitting elements  7  and end faces  5   a  of respective optical fibers  5  to each other in the state where lens array  2  is disposed between optoelectric converting device  3  and optical fibers  5 . 
         [0338]    Lens array  2  is further described; as shown in  FIG. 48 , lens array  2  includes lens array body  4 . Lens array body  4  is formed to have a substantially trapezoidal external shape in a longitudinal sectional view, a substantially rectangular shape in a plan view as shown in  FIG. 49 , and a rectangular shape in a side view as shown in  FIGS. 50 and 51 . 
         [0339]    As shown in  FIGS. 48 and 52 , lens array  2  has a plurality of (eight) first lens surfaces (convex lens surfaces)  11  that are plano-convex and equal in number to light emitting elements  7 , on bottom face  4   a  (plane) as a first surface of lens array body  4  in  FIG. 48  facing optoelectric converting device  3 . The plurality of first lens surfaces  11  are formed to align in the predetermined alignment direction (direction perpendicular to the sheet of  FIG. 48 , longitudinal direction in  FIG. 52 ) corresponding to light emitting elements  7 . First lens surfaces  11  are arranged at the same pitch as light emitting elements  7 . It is preferred that optical axis OA( 1 ) on each first lens surface  11  coincide with the central axis of laser light L emitted from light emitting element  7  corresponding to first lens surface  11 . 
         [0340]    As shown in  FIG. 48 , laser light L emitted from each light emitting element  7  corresponding to first lens surface  11  is incident on first lens surface  11 . Each first lens surface  11  collimates incident laser light L from light emitting element  7 , and causes the collimated light to move forth into lens array body  4 . 
         [0341]    As shown in  FIGS. 48 and 50 , lens array  2  has the plurality of second lens surfaces (convex lens surfaces)  12  equal in number to first lens surfaces  11 , on left end face  4   b  (plane) in  FIG. 48  as a second surface of lens array body  4  facing end faces  5   a  of optical fiber  5 . The plurality of second lens surfaces  12  are formed to align in the same direction as the alignment direction of first lens surfaces  11 . Second lens surfaces  12  are arranged at the same pitch as first lens surfaces  11 . Optical axis OA( 2 ) on each second lens surface  12  is preferably disposed on the same axis as the central axis of end face  5   a  of optical fiber  5  corresponding to second lens surface  12 . 
         [0342]    As shown in  FIG. 48 , laser light L from each light emitting element  7 , having been incident on first lens surface  11  corresponding to second lens surface  12  and moved forth through the optical path in lens array body  4 , is incident on second lens surface  12  in the state where the central axis of the laser light coincides with optical axis OA( 2 ) on second lens surface  12 . Each second lens surface  12  emits incident laser light L from light emitting element  7  toward end face  5   a  of optical fiber  5  corresponding to second lens surface  12 . 
         [0343]    Thus, light emitting elements  7  and respective end faces  5   a  of optical fibers  5  are optically coupled to each other via first lens surfaces  11  and second lens surfaces  12 . 
         [0344]    Furthermore, as shown in  FIGS. 48 and 52 , third lens surfaces  13  equal in number to first light receiving elements  8  (also equal in number to light emitting elements  7 , optical fibers  5 , first lens surfaces  11  and second lens surfaces  12  in this embodiment) are formed at left adjacent positions in  FIG. 48  to first lens surfaces  11 , on bottom face  4   a  of lens array body  4 . Third lens surfaces  13  are formed to align in the predetermined alignment direction corresponding to first light receiving elements  8 , that is, the same direction as the alignment direction of first lens surface  11 . Third lens surfaces  13  are arranged at the same pitch as first light receiving elements  8 . Optical axis OA( 3 ) on each third lens surface  13  preferably coincides with the central axis of light receiving surface of first light receiving element  8  corresponding to third lens surface  13 . 
         [0345]    As shown in  FIG. 48 , monitor light M from each light emitting element  7  corresponding to third lens surface  13  is incident on third lens surface  13  from the inside of lens array body  4 . Each third lens surface  13  emits incident monitor light M from light emitting element  7  toward first light receiving element  8  corresponding to third lens surface  13 . 
         [0346]    Furthermore, as shown in  FIGS. 48 and 51 , lens array body  4  includes total reflection surface  4   d  at the right upper end in  FIG. 48 . Total reflection surface  4   d  is formed into an inclining surface where the upper end is located left to the bottom end in  FIG. 48  (i.e. on a side of after-mentioned concave part  14 ). Total reflection surface  4   d  lies in the optical path of laser light L from each light emitting element  7 , between first lens surface  11  and after-mentioned first optical surface  14   a  of concave part  14 . 
         [0347]    As shown in  FIG. 48 , laser light L from each light emitting element  7 , having been incident on first lens surface  11 , is incident on such total reflection surface  4   d  from the bottom in  FIG. 48  at an incident angle of at least the critical angle. Total reflection surface  4   d  totally reflects incident laser light L from each light emitting element  7  toward the left in  FIG. 48 . 
         [0348]    Note that a reflection film made of Au, Ag, Al or the like may be coated onto total reflection surface  4   d.    
         [0349]    As shown in  FIGS. 48 and 49 , concave part  14  is formed in a reentrant manner on top face  4   c  (plane) of lens array body  4  in  FIG. 48  as third surface so that the optical paths connecting first lens surfaces  11  and second lens surfaces  12  pass through therein. Top face  4   c  is formed parallel to bottom face  4   a.    
         [0350]    Here, as shown in  FIG. 48 , concave part  14  has first optical surface  14   a  forming a part of the inner surface (right side face of concave part  14  in  FIG. 48 ). First optical surface  14   a  is formed into an inclining surface having a predetermined inclining angle to left end face  4   b  where the upper end is located right to the bottom end in  FIG. 48  (i.e. on a side of total reflection surface  4   d ). 
         [0351]    As shown in  FIG. 48 , laser light L from each light emitting element  7 , having been totally reflected by total reflection surface  4   d , is incident on such first optical surface  14   a  at a predetermined incident angle. However, the incident direction of laser light L from each light emitting element  7  onto first optical surface  14   a  is perpendicular to left end face  4   b.    
         [0352]    As shown in  FIG. 48 , concave part  14  has second optical surface  14   b , which is a part of the inner surface and opposite to first optical surface  14   a  at the left in  FIG. 48  (left side face of concave part  14  in  FIG. 48 ). Second optical surface  14   b  has a predetermined inclining angle to left end face  4   b.    
         [0353]    Note that, in this embodiment, the inclining angle of second optical surface  14   b  with reference to left end face  4   b (0°) is represented as 180−θ[°], provided that the inclining angle of first optical surface  14   a  is θ[°] with reference to left end face  4   b . That is, in this embodiment, first optical surface  14   a  and second optical surface  14   b  have a shape that is line-symmetry with respect to symmetry axis AS that is perpendicular to bottom face  4   a  and indicated by a chain double-dashed line in  FIG. 48 . 
         [0354]    Furthermore, as shown in  FIG. 48 , thin reflecting/transmitting layer  17  having a uniform thickness is disposed on first optical surface  14   a . The surface of reflecting/transmitting layer  17  on the side of first optical surface  14   a  is in closely contact with first optical surface  14   a.    
         [0355]    Moreover, as shown in  FIG. 48 , first reflecting/transmitting layer  17  is disposed on first optical surface  14   a  in the state where first reflecting/transmitting layer  17  is formed over the entire surface of first optical plate  15  (undersurface in  FIG. 48 ). Here, as shown in  FIG. 48 , first optical plate  15  is formed into a plate having a uniform thickness and parallel to first optical surface  14   a , and formed to have a predetermined refractive index according to the material of first optical plate  15 . First optical plate  15  is formed to have a size in a direction perpendicular to the sheet of  FIG. 48  on which entire laser light L from each light emitting element  7  can be incident. 
         [0356]    As shown in  FIG. 48 , second optical plate  16  is disposed on second optical surface  14   b . The surface of second optical plate  16  on the side of second optical surface  14   b  is closely in contact with second optical surface  14   b . As shown in  FIG. 48 , second optical plate  16  is formed into a plate having a uniform thickness parallel to second optical surface  14   b , and formed to have the same refractive index as that of first optical plate  15 . Second optical plate  16  is formed into a size in a direction perpendicular to the sheet of  FIG. 48  on which entire laser light L from each light emitting element  7  can be incident. Second optical plate  16  may be made of the same material as that of first optical plate  15 . In this embodiment, second optical plate  16  is formed to have the same air-converted length as that of first optical plate  15 . 
         [0357]    Furthermore, as shown in  FIG. 48 , filler  18  having the same refractive index as that of lens array body  4  fills concave part  14  so as to cover first optical plate  15  and second optical plate  16  in a space formed by concave part  14  from substantially above without gap. 
         [0358]    Moreover, in this embodiment, filler  18  is made of light-transmitting adhesive. First optical plate  15  and second optical plate  16  are bonded to lens array body  4  by the adhesive force of filler  18 . Ultraviolet-set resin or thermoset resin that has the same refractive index as that of lens array body  4  may be used as filler  18  also functioning as adhesive. More specifically, for instance, in the case of forming lens array body  4  using ARTON made by JSR as an annular olefin resin, filler  18  may be A1754B made by TECS, which is UV-curable resin. As to each of ARTON and A1754B, the refractive indices of light with a wavelength of 850 nm, which are calculated on the basis of the refractive index and Abbe number for d line and disclosed by the manufacturer, are 1.50. However, the materials of filler  18  and lens array body  4  are not limited thereto. 
         [0359]    First reflecting/transmitting layer  17 , first optical plate  15 , filler  18  and second optical plate  16 , which are thus disposed in concave part  14 , exert a light separating function and an optical path adjusting function that couple laser light L from each light emitting element  7  to end face  5   a  of optical fiber  5  or first light receiving element  8 , as described below. 
         [0360]    More specifically, as shown in  FIG. 48 , laser light L from each light emitting element  7 , having been incident on first optical surface  14   a , is incident on first reflecting/transmitting layer  17  immediately thereafter. First reflecting/transmitting layer  17  reflects incident laser light L from each light emitting element  7  toward third lens surface  13  side at a predetermined reflectance while allowing the light to pass through toward first optical plate  15  side at a predetermined transmittance. 
         [0361]    Here, as shown in  FIG. 48 , first reflecting/transmitting layer  17  reflects a part of laser light L from each light emitting element  7  (light of the amount of reflectance), having been incident on first reflecting/transmitting layer  17 , as monitor light M from each light emitting element  7  that corresponds to each light emitting element  7 , toward third lens surface  13  side corresponding to monitor light M. 
         [0362]    Monitor light M from each light emitting element  7  thus reflected by first reflecting/transmitting layer  17  moves forth in lens array body  4  toward third lens surface  13  side and is subsequently emitted from third lens surface  13  toward corresponding first light receiving element  8 . 
         [0363]    Here, for instance, in the case of coating first optical plate  15  with a single layer film of Cr using a publicly known coating technique to form first reflecting/transmitting layer  17 , reflectance of first reflecting/transmitting layer  17  can be 30% and transmittance can be 30% (absorptance of 40%). First reflecting/transmitting layer  17  may be formed using a single metal single layer film of Ni, Al or the like, which is other than Cr. In the case of coating first optical plate  15  with a publicly known dielectric multilayer film of Tiθ 2 , Siθ 2  or the like using a publicly known coating technique to form first reflecting/transmitting layer  17 , for instance, the reflectance of first reflecting/transmitting layer  17  can be 20% and the transmittance can be 80%. Instead, the reflectance and transmittance of first reflecting/transmitting layer  17  can be set to desired values in accordance with the material, thickness and the like of first reflecting/transmitting layer  17  within a limit where an amount of monitor light M that is considered sufficient for monitoring the output of laser light L can be acquired. First reflecting/transmitting layer  17  can be coated using a coating technique, such as Inconel deposition. Furthermore, for instance, first reflecting/transmitting layer  17  may be made of a glass filter. 
         [0364]    On the other hand, laser light L from each light emitting element  7 , having passed through first reflecting/transmitting layer  17 , passes through first optical plate  15  and subsequently is incident on filler  18 . Laser light L from each light emitting element  7 , having been incident on filler  18 , moves forth through the optical path in filler  18  toward second lens surface  12  side. 
         [0365]    At this time, filler  18  is formed to have the same refractive index as that of lens array body  4 , thereby allowing the optical path of laser light L from each light emitting element  7  in filler  18  to be maintained parallel to the optical path of laser light L connecting total reflection surface  4   d  and first optical surface  14   a.    
         [0366]    This will be described in detail. Provided that first optical surface  14   a , the interface between first reflecting/transmitting layer  17  and first optical plate  15 , and the interface between first optical plate  15  and filler  18  are parallel to each other, following Equations 4 and 5 based on the Snell&#39;s law hold. 
         [0000]      n 1  sin θ 1 =n 2  sin θ 2   (Equation 4)
 
         [0000]      n 2  sin θ 2 =n 1  sin θ 3   (Equation 5)
 
         [0367]    Note that, in Equations 4 and 5, n 1  represents the refractive index of lens array body  4  and filler  18 , and n 2  represents refractive index of first optical plate  15 . These n 1  and n 2  are acquired with reference to light having the same wavelength. θ 1  in Equation 4 represents the incident angle of laser light L from each light emitting element  7  onto first optical surface  14   a. θ   2  in Equations 4 and 5 represents the emission angle from the interface between first reflecting/transmitting layer  17  and first optical plate  15  concerning laser light L from each light emitting element  7 , and the incident angle of laser light L from each light emitting element  7  onto the interface between first optical plate  15  and filler  18 , respectively. Note that, the refraction of laser light L at first reflecting/transmitting layer  17  is neglected here, because the thickness of first reflecting/transmitting layer  17  (measurement in the optical path direction) is significantly thin in comparison with lens array body  4 , first optical plate  15  and filler  18 . θ 3  in Equation 5 represents the emission angle from the interface between first optical plate  15  and filler  18  concerning laser light L from each light emitting element  7 . The plane normal direction of first optical surface  14   a  is adopted as the references (0°) of θ 1  to θ 3 . 
         [0368]    Because the right side of Equation 4 and the left side of Equation 5 are identical to each other, the following equation is derived. 
         [0000]      n 1  sin θ 1 =n 1  sin θ 3   (Equation 6)
 
         [0369]    According to Equation 6, θ 3 =θ 1 . This represents that the optical path of laser light L from each light emitting element  7  in filler  18  is parallel to the optical path of laser light L connecting total reflection surface  4   d  and first optical surface  14   a.    
         [0370]    Thus, laser light L from each light emitting element  7 , having moved forth through the optical path in filler  18 , passes through second optical plate  16  and subsequently is incident on second optical surface  14   b  to return to the optical path in lens array body  4  as shown in  FIG. 48 , while parallelity to the optical path of laser light L connecting total reflection surface  4   d  and first optical surface  14   a  is maintained. 
         [0371]    Here, provided that the interface between second optical surface  14   b  and second optical plate  16  and the interface between second optical plate  16  and filler  18  are parallel to each other, and second optical surface  14   b  is line-symmetric to first optical surface  14   a , following Equations 7 and 8 based on the Snell&#39;s law hold. 
         [0000]      n 1  sin θ 1 =n 2  sin θ 2   (Equation 7)
 
         [0000]      n 2  sin θ 2 =n 1  sin θ 4   (Equation 8)
 
         [0372]    Note that, in Equations 7 and 8, n 1  represents the refractive index of lens array body  4  and filler  18 , as with Equations 4 to 6, and n 2  represents the refractive index of second optical plate  16  and also represents the refractive index of first optical plate  15 . This is as described on Equations 4 and 5. θ 1  in Equation 7 represents the incident angle of laser light L from each light emitting element  7  onto the interface between filler  18  and second optical plate  16 , and also represents the emission angle from the interface between first optical plate  15  and filler  18  concerning laser light L from each light emitting element  7 . This is as described on Equation 6. θ 2  in Equations 7 and 8 represents the emission angle from the interface between filler  18  and second optical plate  16  concerning laser light L from each light emitting element  7 , and the incident angle of laser light L from each light emitting element  7  onto second optical surface  14   b  (i.e. the interface between second optical plate  16  and second optical surface  14   b ). θ 2  represents the emission angle from the interface between first reflecting/transmitting layer  17  and first optical plate  15  concerning laser light L from each light emitting element  7 , and also represents the incident angle of laser light L from each light emitting element  7  onto the interface between first optical plate  15  and filler  18 . This is as described on Equations 4 and 5. θ 4  in Equation 8 represents the emission angle from second optical surface  14   b  concerning laser light L from each light emitting element  7 . The plane normal direction of second optical surface  14   b  is adopted as the references) (0°) of θ 1 , θ 2  and θ 4  in Equations 7 and 8. 
         [0373]    Because the right side of Equation 7 and the left side of Equation 8 are identical to each other, Equation 9 is derived. 
         [0000]      n 1  sin θ 1 =n 1  sin θ 4   (Equation 9)
 
         [0374]    According to Equation 9, θ 4 =θ 1 . This represents that the optical path of laser light L from each light emitting element  7  after second optical surface  14   b  is parallel to the optical path of laser light L from each light emitting element  7  in filler  18 . 
         [0375]    Here, it has been described above that the optical path of laser light L from each light emitting element  7  in filler  18  was parallel to the optical path of laser light L connecting total reflection surface  4   d  and first optical surface  14   a . Accordingly, it can be said that the optical path of laser light L from each light emitting element  7  after second optical surface  14   b  is parallel to the optical path of laser light L connecting total reflection surface  4   d  and first optical surface  14   a.    
         [0376]    Furthermore, in consideration that first optical surface  14   a  and second optical surface  14   b  are line-symmetric, the air-converted lengths of first optical plate  15  and second optical plate  16  are identical to each other, the thickness of reflecting/transmitting layer  17  is negligible, and laser light L from each light emitting element  7  is incident on first optical surface  14   a  from the direction perpendicular to symmetry axis AS, it can be said that the optical path of laser light L after second optical surface  14   b  is located on the same line as the optical path of laser light L connecting total reflection surface  4   d  and first optical surface  14   a.    
         [0377]    More specifically, in this embodiment, laser light L from each light emitting element  7 , having been incident on first optical surface  14   a  at incident angle θ 1 , is refracted at refraction angle θ 2  when being incident on first optical plate  15 , and moves forth to the upper left in  FIG. 48 . This refraction causes a deviation (so-called lateral deviation) in the direction perpendicular to the optical path length direction (lateral direction in  FIG. 48 ) between the optical path of laser light L from each optical element  7  that connects total reflection surface  4   d  and first optical surface  14   a  to each other and the optical path in filler  18 . However, in this embodiment, laser light L from each light emitting element  7 , having moved forth through the optical path in filler  18 , is refracted at refraction angle θ 2  and moves forth to the lower left in  FIG. 48  when being incident on second optical plate  16 , and subsequently is emitted from second optical surface  14   b  at emission angle θ 1 . This can correct a lateral deviation, in this embodiment. Thus, second optical plate  16  corrects the optical path of laser light L such that the optical path of laser light L from each light emitting element  7  after second optical surface  14   b  is located on the same line as the optical path of laser light L connecting total reflection surface  4   d  and first optical surface  14   a.    
         [0378]    As described above, laser light L from each light emitting element  7 , having returned from second optical surface  14   b  to the optical path in lens array body  4 , moves forth through the optical path in lens array body  4  toward second lens surface  12  side, and subsequently is emitted by second lens surface  12  toward end face  5   a  of optical fiber  5  corresponding second lens surface  12 . 
         [0379]    The aforementioned configuration allows first reflecting/transmitting layer  17  to split laser light L from each light emitting element  7 , having been incident on first lens surface  11 , toward second lens surface  12  side and third lens surface  13  side. Monitor light M split toward each third lens surface  13  side is emitted by third lens surface  13  toward first light receiving element  8  side. As a result, monitor light M can be securely acquired. Adoption of first reflecting/transmitting layer  17  capable of being easily formed to have a certain extent of area, as a configuration of acquiring such monitor light M, facilitates manufacturing of lens array  2 . 
         [0380]    This embodiment can secure linearity between the optical path in a predetermined range on the incident side onto first optical surface  14   a  (optical path between total reflection surface  4   d  and first optical surface  14   a ) and optical path on the emitting side from second optical surface  14   b . In the case of product inspection, this can reduce the number of spots required to be adjusted in measurements for canceling a deviation from the center of each second lens surface  12  concerning laser light L, which has been from each light emitting element  7  and incident on each second lens surface  12 , if such a deviation is confirmed. The measurement adjustment may be change in the shape of the mold. More specifically, if a design is adopted that cannot secure linearity between the optical path on the incident side onto first optical surface  14   a  and the optical path on the emitting side from second optical surface  14   b , both optical surfaces  14   a  and  14   b  of concave part  14  are sometimes required to be reset to the respective optimal inclining angles separately from each other in order to correct the axial deviation of incident light onto second lens surface  12  to be within a permissible limit. In contrast, in this embodiment, it is provided that total reflection direction of total reflection surface  4   d  is perpendicular to left end face  4   b  and both optical surfaces  14   a  are  14   b  are secured to be line-symmetric, thereby negating the need for performing complicated and intricate measurement adjustment by trial and error, such as appropriate setting of an inclining angle without no correlation between both optical surfaces  14   a  and  14   b . If linearity between the optical path on the incident side onto first optical surface  14   a  and the optical path on the emitting side from second optical surface  14   b  can be secured, the position of second lens surface  12  can be simply determined in designing. 
         [0381]    This can contribute to further facilitation of manufacturing lens array  2 . 
         [0382]    Furthermore, as described above, coating of first optical plate  15  with the single metal single layer film or the dielectric multilayer film to form first reflecting/transmitting layer  17  allows the configuration and manufacturing process of first reflecting/transmitting layer  17  to be simplified, thereby enabling further facilitation of manufacturing to be realized. Moreover, the coating allows first reflecting/transmitting layer  17  to be formed significantly thin (e.g. 1 μm or less). Accordingly, a lateral deviation of laser light L caused by the refraction on transmission of laser light L from each light emitting element  7  through first reflecting/transmitting layer  17  can be reduced to a negligible level. This can secure linearity between the optical path on the incident side onto first optical surface  14   a  and the optical path on the emitting side from second optical surface  14   b  in a more accurate manner. 
         [0383]    Furthermore, preferably, the inclining angle of first optical surface  14   a  is within a range from 130° to 140° (more preferably, 135°) in the counterclockwise direction in  FIG. 48  with reference to left end face  4   b  (0°); the inclining angle of second optical surface  14   b  is within a range from 40° to 50° (more preferably, 45°) in the counterclockwise direction in  FIG. 48  with reference to left end face  4   b (0°). Note that, the symmetry between first optical surface  14   a  and second optical surface  14   b  is maintained. Furthermore, total reflection surface  4   d  is formed parallel to second optical surface  14   b . This configuration allows a reasonable design when totally reflecting incident laser light L from each light emitting element  7  on total reflection surface  4   d  toward concave part  14  side while splitting laser light L, having been incident on first optical surface  14   a , toward second lens surface  12  side and third lens surface  13  side. In particular, in the case where the inclining angle of first optical surface  14   a  is 135° and the inclining angles of second optical surface  14   b  and total reflection surface  4   d  are 45°, design of surfaces  14   a ,  14   b  and  4   d  or determination of accuracy in measuring thereof is further simplified. 
         [0384]    Furthermore, bottom face  4   a  and left end face  4   b  may be formed perpendicular to each other. Optical axis OA( 1 ) on first lens surface  11  and optical axis OA( 3 ) on third lens surface  13  may be formed perpendicular to bottom face  4   a . Optical axis OA( 2 ) on second lens surface  12  may be formed perpendicular to left end face  4   b . This configuration can relax accuracy in measuring that is required for lens array  2  to secure the optical path connecting light emitting element  7  and first light receiving element  8  and the optical path connecting light emitting element  7  and end face  5   a  of optical fiber  5 , thereby allowing further facilitation of manufacturing to be realized. More specifically, for instance, in the case where optical axis OA( 3 ) on third lens surface  13  is configured to be inclined at an acute angle to optical axis OA( 1 ) on first lens surface  11 , there is a possibility that a slight measurement error in the longitudinal direction in  FIG. 48  prevents monitor light M, having been emitted from third lens surface  13 , from being coupled to first light receiving element  8 . In contrast, in this embodiment, optical axis OA( 1 ) on first lens surface  11  and optical axis OA( 3 ) on third lens surface  13  are parallel to each other. Even if lens array  2  causes a slight measurement error in the longitudinal direction in  FIG. 48 , the beam diameter of monitor light M emitted from third lens surface  13  merely becomes larger or smaller with respect to a designed value, thus allowing the monitor light M to be appropriately received by each first light receiving element  8 . If optical axis OA( 2 ) on second lens surface  12  has an angle other than the right angle to optical axis OA( 1 ) on first lens surface  11 , there is a possibility that a slight measurement error in the lateral direction in  FIG. 48  prevents laser light L, having been emitted from second lens surface  12  from being coupled to the end face of optical fiber  5 . 
         [0385]    In contrast, in this embodiment, optical axis OA( 1 ) on first lens surface  11  and optical axis OA( 2 ) on second lens surface  12  are formed to be perpendicular to each other. Accordingly, even if lens array  2  causes a slight measurement error in the lateral direction in  FIG. 48 , the beam diameter of laser light L emitted from second lens surface  12  merely becomes slightly larger or smaller with respect to a designed value, thus allowing the laser light L to be appropriately coupled to the end face of optical fiber  5 . 
         [0386]    In addition to the configuration, in this embodiment, as shown in  FIGS. 48 and 49 , concave part  14  is formed into a shape accommodating bottom surface (bottom face in  FIG. 48 )  14   e  and all sides  14   a  to  14   d  within a range indicated by the external shape of opening  14   f  of concave part  14  in the case of being viewed in the plane normal direction of top face  4   c  (from the top in  FIG. 48 ). In other words, concave part  14  is formed so as to accommodate projected surfaces of bottom surface  14   e  and all sides  14   a  to  14   d  in the plane normal direction of top face  4   c  within the range indicated by the external shape of opening  14   f . As shown in  FIG. 49 , opening  14   f  is formed into a rectangular shape elongated in the longitudinal direction in  FIG. 49  and encompassed therearound by top face  4   c . Sides  14   c  and  14   d  other than first optical surface  14   a  and second optical surface  14   b  are formed perpendicular to top face  4   c . This configuration allows concave part  14  to be formed into a shape capable of securing demoldability. This can realize effective manufacturing of lens array  2  using a mold. 
         [0387]    Third lens surfaces  13  and first light receiving elements  8  corresponding thereto are not necessarily provided so as to be equal in number to light emitting elements  7 . It is sufficient that at least one set is provided. In this case, at first reflecting/transmitting layer  17 , in laser light L from each light emitting element  7  incident on each first lens surface  11 , only a part of laser light L to which third lens surfaces  13  correspond is reflected as monitor light M. The other part of laser light L is reflected but is not used as monitor light M. 
         [0388]    First optical plate  15  and second optical plate  16  may be formed using inexpensive material, such as BK7 or colorless plate glass. 
         [0389]    Furthermore, the difference of refractive indices between first optical plate  15  and lens array body  4  may be such that the incident angle of laser light L from each light emitting element  7  onto first optical plate  15  does not exceed the critical angle. For instance, as described above, in the case of assuming that the inclining angle of first optical surface  14   a  (i.e. inclining angle of first optical plate  15 ) is 135° and the refractive index of lens array body  4  is 1.64, it is sufficient that the refractive index of first optical plate  15  is at least 1.16. 
         [0390]    (Variation) 
         [0391]    A variation of this embodiment will now be described mainly on difference from the configuration in  FIG. 48  with reference to  FIGS. 53 to 57 . 
         [0392]    In this variation, elements having configurations identical or similar to those in  FIG. 48  will be described using the same reference signs. 
         [0393]      FIG. 53  is a configurational diagram schematically showing an overview of optical module  21  in this variation together with a longitudinal sectional view of lens array  22  in this variation.  FIG. 54  is a plan view of lens array  22  shown in  FIG. 53 . 
         [0394]      FIG. 55  is a left side view of  FIG. 54 .  FIG. 56  is a right side view of  FIG. 54 .  FIG. 57  is a bottom view of  FIG. 54 . 
         [0395]    In this variation, as a difference from the configuration in  FIG. 48 , means is adopted for mechanically positioning optoelectric converting device  3  and optical fibers  5  when fixing optoelectric converting device  3  and optical fibers  5  to lens array  22 . 
         [0396]    More specifically, as shown in  FIGS. 53 and 57 , in this variation, first lens surfaces  11  and second lens surfaces  12  are formed on bottom surface  23   a  of first counter-bore part  23  (first surface in this variation) provided with a dent in bottom face  4   a  of lens array body  4 . Bottom surface  23   a  of first counter-bore part  23  is formed parallel to bottom face  4   a . As shown in  FIG. 57 , first counter-bore part  23  is formed to have such a width in the longitudinal direction in  FIG. 57  (hereinafter, referred to as the lens alignment direction) that the widthwise edges of first counter-bore part  23  are disposed slightly outwardly from lens surfaces  11  and  13  that are arranged outermost in the lens alignment direction. In this variation, lens array body  4  is formed wider in the lens alignment direction than the width of first counter-bore part  23  in the lens alignment direction. In accordance with this, as shown in  FIG. 57 , bottom face  4   a  includes portions that extend outwardly in the lens alignment direction from both ends of first counter-bore part  23 . As shown in  FIG. 57 , at the both extended portions of bottom face  4   a  that extend outwardly in the lens alignment direction from both ends of first counter-bore part  23 , two pairs, four in total, of plano-convex fitting holes  24  are formed so as to be disposed across first counter-bore part  23  as a structure for positioning optoelectric converting device  3 . Fitting holes  24  are fitted with fitting pins, not shown, penetrating through semiconductor substrate  6  in the state where semiconductor substrate  6  is in contact with extended portions of bottom face  4   a . This allows optoelectric converting device  3  to be mechanically positioned when optoelectric converting device  3  is fixed to lens array  22 . 
         [0397]    As shown in  FIGS. 53 and 55 , in this variation, second lens surfaces  12  are formed on bottom surface  26   a  (second surface in this variation) of second counter-bore part  26  provided with a dent in left end face  4   b  of lens array  4 . Bottom surface  26   a  of second counter-bore part  26  is formed parallel to left end face  4   b . As shown in  FIG. 55 , second counter-bore part  26  is formed to have such a width in lens alignment direction that the widthwise edges of second counter-bore part  26  are disposed slightly outwardly from lens surfaces  12  arranged outermost in the lens alignment direction. As shown in  FIG. 55 , in this variation, left end face  4   b  includes portions that extend outwardly in the lens alignment direction from both ends of second counter-bore part  26 . As shown in  FIG. 55 , at the both extended portions of left end face  4   b , a pair, two in total, of fitting pins  27  are formed so as to be disposed across second counter-bore part  26  in a protruding manner as a structure for positioning optical fibers  5 . Fitting pins  27  are fitted into fitting holes, not shown, formed in connector  10  in the state where connector  10  is in contact with the extended portions of left end face  4   b . This allows optical fibers  5  to be mechanically positioned when optical fibers  5  are fixed to lens array  22 . 
         [0398]    The configuration of this variation can also exert excellent working-effect similar to those in  FIG. 48 . Furthermore, in this variation, optoelectric converting device  3  and optical fiber  5  can be simply positioned with respect to lens array  22  using fitting holes  24  and fitting pins  27 . This allows optoelectric converting device  3  and optical fiber  5  to be simply fixed to lens array  22 . 
         [0399]    As shown in  FIG. 53 , in this variation, the side surface of concave part  14  is formed to extend vertically upward from the upper ends of first and second optical surfaces  14   a  and  14   b.    
         [0400]    Instead of aforementioned fitting holes  24 , through holes each having the same diameter as that of fitting hole  24  and penetrating lens array body  4  may be formed. As the structure for positioning optical fiber  5 , fitting holes or through holes may be formed on the side of lens array body  4  and fitting pins may be formed on the side of optical fiber  5 . Likewise, as the structure for positioning optoelectric converting device  3 , fitting pins may be formed on the side of lens array body  4  and fitting holes or through holes may be formed on the side of optoelectric converting device  3 . The positioning of optical fiber  5  and optoelectric converting device  3  is not limited to mechanical positioning. Instead, for instance, the positioning may be performed according to an optical method by optically recognizing a mark formed on lens array body  4 . 
         [0401]    Although not shown, in a variation other than such a variation, reflecting/transmitting layer  17  may be formed on the surface of first optical plate  15  on the side of filler  18 . In this case, first optical plate  15  is disposed in the state where it is in closely contact with first optical surface  14   a , and reflecting/transmitting layer  17  is disposed adjacent to first optical surface  14   a.    
         [0402]    In the configuration in  FIG. 48 , an anti-reflection film (AR coating) may be formed on the surface of first optical plate  15  on the side of filler  18 . 
       Embodiment 13 
       [0403]    Embodiment 13 of a lens array and an optical module provided therewith according to the present invention will now be described mainly on difference from Embodiment 12 with reference to  FIG. 58 . 
         [0404]    In this embodiment, elements having configurations identical or similar to those in  FIGS. 48 to 57  will be described using the same reference signs. 
         [0405]      FIG. 58  is a configurational diagram schematically showing an overview of optical module  30  in this embodiment together with a longitudinal sectional view of lens array  31  in this embodiment. 
         [0406]    As shown in  FIG. 58 , this embodiment is different from Embodiment 12 in that first optical plate  15  is bonded on first optical surface  14   a  via first adhesive sheet  32  that has a uniform thickness and a predetermined refractive index, and second optical plate  16  is bonded on second optical surface  14   b  via second adhesive sheet  33  that has a uniform thickness and the refractive index as that of first adhesive sheet  32 . In this embodiment, first reflecting/transmitting layer  17  is arranged adjacent to first optical surface  14   a  in the state where first reflecting/transmitting layer  17  is located between first optical plate  15  and first adhesive sheet  32 . In this embodiment, first adhesive sheet  32  and second adhesive sheet  33  are formed to have the same air-converted length. 
         [0407]    This configuration allows first optical plate  15  and second optical plate  16  to be fixed more stably to lens array body  4 . First adhesive sheet  32  and second adhesive sheet  33  are formed to have the same refractive index. Accordingly, the adverse effect of refraction when laser light L from each light emitting element  7  is incident on first adhesive sheet  32  can be corrected by refraction when laser light L from each light emitting element  7  is incident on second adhesive sheet  33 . Accordingly, as with Embodiment 12, the linearity between the optical path of laser light L from each light emitting element  7  between total reflection surface  4   d  and first optical surface  14   a  and the optical path on the emitting side from second optical surface  14   b  can be secured. 
         [0408]    Furthermore, preferably, first adhesive sheet  32  and second adhesive sheet  33  are configured such that the difference of refractive index from lens array body  4  is 0.35 or less (more preferably, 0). This configuration can suppress Fresnel reflection of laser light L from each light emitting element  7  on the interface between lens array body  4  and first adhesive sheet  32  and the interface between lens array body  4  and second adhesive sheet  33 . This can suppress occurrence of stray light and reduction in coupling efficiency. 
         [0409]    For instance, adhesive thin (e.g. 20 μm) refractive index matching film, such as Fitwell made by Tomoegawa, can be adopted as first adhesive sheet  32  and second adhesive sheet  33 . 
         [0410]    The variation applied to Embodiment 12 is also applicable to this embodiment as it is. 
       Embodiment 14 
       [0411]    Embodiment 14 of a lens array and an optical module provided therewith according to the present invention will now be described mainly on difference from Embodiment 12 with reference to  FIGS. 59 and 60 . 
         [0412]    In this embodiment, elements having configurations identical or similar to those in  FIGS. 48 to 57  will be described using the same reference signs. 
         [0413]      FIG. 59  is a configurational diagram schematically showing an overview of optical module  35  in this embodiment together with a longitudinal sectional view of lens array  36  in this embodiment.  FIG. 60  is a bottom view of lens array  36  shown in  FIG. 59 . 
         [0414]    As shown in  FIGS. 59 and 60 , this embodiment is different in configuration from Embodiment 12 in that the configuration in this embodiment is applicable not only to transmission of optical signals but also to reception of optical signals. 
         [0415]    More specifically, in this embodiment, laser light having the same wavelength is emitted from end face  5   a  of each optical fiber  5  toward lens array  36 . The laser light emitted from each optical fiber  5  has a wavelength different from that of laser light L from each light emitting element  7 . As more specific means, the plurality of light emitting elements, not shown, equal in number to optical fibers  5  are disposed at the end faces of optical fibers  5  on the side opposite to end faces  5   a , and light emitted from the light emitting elements are incident on respective optical fibers  5  corresponding to the light emitting elements. 
         [0416]    The laser light having thus emitted from each optical fiber  5  enters second lens surface  12  corresponding to the optical fiber. 
         [0417]    As shown in  FIG. 59 , in this embodiment, optoelectric converting device  3  includes a plurality of second light receiving elements  37  that are on a surface of semiconductor substrate  6  facing lens array  36  at left adjacent positions of first light receiving elements  8  in  FIG. 59  and receive laser light emitted from respective optical fibers  5 . The plurality of second light receiving elements  37  are arranged equal in number and pitch to second lens surfaces  12  along the same direction as the alignment direction of second lens surfaces  12 . Each second light receiving element  37  may be a photo-detector. 
         [0418]    Furthermore, as shown in  FIGS. 59 and 60 , at positions facing second light receiving elements  37  at bottom face  4   a , a plurality of respective fourth lens surfaces  38  are formed that emit laser light, having been emitted from optical fibers  5  and incident from the inside of lens array body  4 , toward second light receiving elements  37 . The plurality of fourth lens surfaces  38  are provided equal in number and pitch to second lens surfaces  12 , along the same direction as the alignment direction (longitudinal direction in  FIG. 60 ) of second lens surfaces  12 . 
         [0419]    Moreover, as shown in  FIG. 59 , second reflecting/transmitting layer  40  is disposed between second optical surface  14   b  and second optical plate  16 . Second reflecting/transmitting layer  40  is formed over the entire surface of second optical plate  16  (undersurface in  FIG. 59 ), and in closely contact with second optical surface  14   b.    
         [0420]    Here, laser light having been emitted from each optical fiber  5  and incident on second lens surface  12  is incident on second reflecting/transmitting layer  40 . Second reflecting/transmitting layer  40  reflects the incident laser light at a predetermined reflectance toward fourth lens surfaces  38  side while allowing the light to pass through at a predetermined transmittance. 
         [0421]    According to such a configuration, the laser light emitted from each optical fiber  5  passes through second lens surface  12 , second reflecting/transmitting layer  40  and fourth lens surface  38  and is coupled to second light receiving element  37 . Accordingly, bidirectional optical communication can be effectively supported. 
         [0422]    Second reflecting/transmitting layer  40  may be formed using the same material and method as those of first reflecting/transmitting layer  17 . 
         [0423]    In terms of facilitation of design, optical axis OA( 4 ) on fourth lens surface  38  is preferably perpendicular to bottom face  4   a.    
         [0424]    (Variation) 
         [0425]    A variation of this embodiment will now be described mainly on difference from the configuration in  FIG. 59  with reference to  FIG. 61 . 
         [0426]    As shown in  FIG. 61 , the configuration of this variation is different from the configuration in  FIG. 59  in that first optical plate  15  is bonded on first optical surface  14   a  via first adhesive sheet  32  and second optical plate  16  is bonded on second optical surface  14   b  via second adhesive sheet  33 , as with Embodiment 13. 
         [0427]    Besides that, the variation applied to Embodiment 12 is applicable also to this embodiment as it is. 
       Embodiment 15 
       [0428]    Embodiment 15 of a lens array and an optical module provided therewith according to the present invention will now be described mainly on difference from Embodiment 12 with reference to  FIG. 62 . 
         [0429]    In this embodiment, elements having configurations identical or similar to those in  FIGS. 48 to 57  will be described using the same reference signs. 
         [0430]      FIG. 62  is a configurational diagram schematically showing an overview of optical module  42  in this embodiment together with a longitudinal sectional view of lens array  43  in this embodiment. 
         [0431]    As shown in  FIG. 62 , the configuration of this embodiment is different from the configuration of Embodiment 12 in that first reflecting/transmitting layer  17  is formed directly on first optical surface  14   a  by coating or the like, and first optical plate  15  and second optical plate  16  are not provided. 
         [0432]    Such a configuration allows laser light L from each light emitting element  7 , having passed through first reflecting/transmitting layer  17 , to move forth straight toward second lens surface  12  without refraction. As with Embodiment 12, this configuration can also secure linearity between the optical path on the incident side onto first optical surface  14   a  and the optical path on the emitting side from second optical surface  14   b.    
         [0433]    This embodiment can directly form first reflecting/transmitting layer  17  directly on lens array body  4 , and reduce the number of components. 
         [0434]    The variation applied to Embodiment 12 is applicable also to this embodiment as it is. 
       Embodiment 16 
       [0435]    Embodiment 16 of a lens array and an optical module provided therewith according to the present invention will now be described mainly on difference from Embodiment 14 with reference to  FIG. 63 . 
         [0436]    In this embodiment, elements having configurations identical or similar to those in  FIGS. 59 and 60  will be described using the same reference signs. 
         [0437]      FIG. 63  is a configurational diagram schematically showing an overview of optical module in this embodiment 45 together with a longitudinal sectional view of lens array  46  in this embodiment. 
         [0438]    As shown in  FIG. 63 , the configuration of this embodiment is different from the configuration in Embodiment 14 in that first reflecting/transmitting layer  17  is formed directly on first optical surface  14   a , second reflecting/transmitting layer  40  is formed directly on second optical surface  14   b , and first optical plate  15  and second optical plate  16  are not provided in this embodiment. 
         [0439]    The variation applied to Embodiment 14 is applicable also to this embodiment as it is. 
         [0440]    The present invention is not limited to the aforementioned embodiments, and can be modified variously in such an extent that the characteristics of the present invention is not degraded. 
         [0441]    For instance, lens array body  4  may be formed using light-transmitting material (e.g. glass) other than resin material. 
         [0442]    The present invention is applicable to optical transmission members other than optical fibers  5 , such as sheet-shaped optical waveguides. 
         [0443]    The disclosure of Japanese Patent Application No. 2009-291067 filed on Dec. 22, 2009, Japanese Patent Application No. 2010-55929 filed on Mar. 12, 2010, Japanese Patent Application No. 2010-195737 filed on Sep. 1, 2010, Japanese Patent Application No. 2009-295278 filed on Dec. 25, 2009, and Japanese Patent Application No. 2010-2928 filed on Jan. 8, 2010 including the specification, drawing and abstract, is incorporated herein by reference in their entirety.