Abstract:
An optical module comprising: an optical waveguide transports light, the optical waveguide including a first mirror which reflects first light; an adhesive sheet formed over the optical waveguide, the adhesive sheet including a first gap above the first mirror; a first light-transmissive layer formed in the first gap; a lens sheet arranged over the adhesive sheet, the lens sheet including a first lens which is formed above the first light-transmissive layer; and a light-emitting device formed above the lens sheet, the light-emitting device including a light-emitting portion which emits the first light to the first lens.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2014-013773, filed on Jan. 28, 2014, the entire contents of which are incorporated herein by reference. 
       FIELD 
       [0002]    The embodiments discussed herein are related to an optical module, a method for manufacturing the optical module, and an optical transceiver. 
       BACKGROUND 
       [0003]    Small-sized optical modules that are manufacturable at low cost and relatively small compared with those in the optical communication in backbone systems of the related art are desired in optical interconnects. A technology is known in which a lens member and a stem where an optical semiconductor device is disposed are bonded together through a tubular spacer. In addition, a technology is known in which an adhesive material is permeated only on the outside of a frame body which is disposed in the lens member in optical components. 
         [0004]    However, in the above-described technologies of the related art, a problem arises in which voids that are referred to as bubbles or gaps occur in a light-transmission part of a bonding layer which bonds the lens member and an optical waveguide portion in an optical module. 
         [0005]    The followings are reference documents:
   [Document 1] Japanese Laid-open Patent Publication No. 4-354385 and   [Document 2] Japanese Laid-open Patent Publication No. 2006-215288.   
 
       SUMMARY 
       [0008]    According to an aspect of the invention, an optical module comprising: an optical waveguide transports light, the optical waveguide including a first mirror which reflects first light; an adhesive sheet formed over the optical waveguide, the adhesive sheet including a first gap above the first mirror; a first light-transmissive layer formed in the first gap; a lens sheet arranged over the adhesive sheet, the lens sheet including a first lens which is formed above the first light-transmissive layer; and a light-emitting device formed above the lens sheet, the light-emitting device including a light-emitting portion which emits the first light to the first lens. 
         [0009]    The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
         [0010]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  is a top view illustrating one example of the configuration of an optical transceiver according to a first embodiment; 
           [0012]      FIG. 2  is a side view of the optical transceiver according to the first embodiment; 
           [0013]      FIG. 3  is an enlarged partial cross-sectional view taken along line III-III of  FIG. 1 ; 
           [0014]      FIG. 4  is a flow chart illustrating one example of the manufacturing process of the optical transceiver; 
           [0015]      FIG. 5  is a description diagram (part  1 ) illustrating one example of the manufacturing process of the optical transceiver according to the first embodiment; 
           [0016]      FIG. 6  is a description diagram (part  2 ) illustrating one example of the manufacturing process of the optical transceiver according to the first embodiment; 
           [0017]      FIG. 7  is a graph illustrating the relationship between the thickness of an adhesive sheet and filling failure of a light-transmissive resin; 
           [0018]      FIG. 8  is a description diagram illustrating the focal point of light in the optical transceiver according to the first embodiment; 
           [0019]      FIG. 9A  is a description diagram (part  1 ) illustrating the focal point of light in an optical transceiver of the related art; 
           [0020]      FIG. 9B  is a description diagram (part  2 ) illustrating the focal point of light in the optical transceiver of the related art; 
           [0021]      FIG. 10  is a description diagram illustrating a modification example of the first embodiment; 
           [0022]      FIG. 11  is a description diagram illustrating an optical module of an optical transceiver according to a second embodiment; 
           [0023]      FIG. 12  is a description diagram (part  1 ) illustrating one example of the manufacturing process of the optical transceiver according to the second embodiment; 
           [0024]      FIG. 13  is a description diagram (part  2 ) illustrating one example of the manufacturing process of the optical transceiver according to the second embodiment; and 
           [0025]      FIG. 14  is a description diagram illustrating a modification example of the second embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0026]    Hereinafter, the first and second preferred embodiments of the technology to be disclosed will be described in detail with reference to the accompanying drawings. 
       First Embodiment 
     Basic Configuration of Optical Transceiver 
       [0027]      FIG. 1  is a top view illustrating one example of the configuration of an optical transceiver according to the first embodiment.  FIG. 2  is a side view of the optical transceiver according to the first embodiment. As illustrated in  FIG. 1  and  FIG. 2 , an optical transceiver  100  includes a printed board  101 , an optical board  103 , and a waveguide member  130 . 
         [0028]    The printed board  101  is a board that transmits an electric signal. An electrical connector  102  is disposed in the printed board  101 . The electrical connector  102  connects the printed board  101  and the optical board  103 . The optical board  103 , for example, includes a core layer and an electrode layer that is patterned on both surfaces of the core layer. 
         [0029]    A light-receiving device  111  and a light-emitting device  112  are mounted face down on the upper surface of the optical board  103 . Face down mounting means that a light-receiving portion  111   a  (refer to  FIG. 3 ) of the light-receiving device  111  and a light-emitting portion (not illustrated) of the light-emitting device  112  are disposed facing the optical board  103 . 
         [0030]    The light-receiving device  111  receives light. The light-receiving device  111 , for example, is a photodiode (PD) array. The light-emitting device  112  emits light. The light-emitting device  112 , for example, is a vertical cavity semiconductor emission laser (VCSEL) array. 
         [0031]    A transimpedance amplifier (TIA)  113  and a drive IC  114  are arranged on the optical board  103 . The TIA  113  converts a current from the light-receiving device  111  into a voltage. The drive IC  114  drives the light-emitting device  112  by supplying a drive current to the light-emitting device  112 . The TIA  113  and the drive IC  114  are electrically connected to the printed board  101  through the optical board  103  and the electrical connector  102 . 
         [0032]    In addition, a cooling member such as a heat sink is disposed on the upper surface of the light-receiving device  111  and the light-emitting device  112  that are disposed on the optical board  103  so as to cool the light-receiving device  111  and the light-emitting device  112  by interposing, for example, a heat dissipation sheet or heat dissipation grease between the diodes and the cooling member. In this case, the heat sink is mounted on the optical board  103  by, for example, fixing with metal fasteners or screws. 
         [0033]    A lens sheet  120  that is a lens member is attached on the surface of the optical board  103  on which the light-receiving device  111  and the light-emitting device  112  are not disposed with a board adhesive sheet  125  interposed between the lens sheet  120  and the optical board  103 . The lens sheet  120  is made of a transparent material, and a lens portion  120   a  (refer to  FIG. 3 ) for condensing light is formed in part of the lens sheet  120 . 
         [0034]    A bonding layer  127  is formed on the lower surface of the lens sheet  120 . The bonding layer  127  bonds the lens sheet  120  and the waveguide member  130 . 
         [0035]    The waveguide member  130  not only transports light that is transmitted through the lens portion  120   a  but also transports and emits the light. Specifically, the waveguide member  130  transports light that is incident on the light-receiving device  111  or light that is output from the light-emitting device  112 . The waveguide member  130  includes a core  130   a  and a cladding  130   b  that realize an optical waveguide. The core  130   a  is positioned at the central portion of the waveguide member  130 . The cladding  130   b  has a lower refractive index than the core  130   a  and is arranged around the core  130   a.    
         [0036]    Accordingly, light in the core  130   a  is transported while being totally reflected at the interface between the core  130   a  and the cladding  130   b . A polymer waveguide, for example, that includes an epoxy resin or an acrylate resin is used in the waveguide member  130 . A low-cost waveguide that propagates multimode light may be used, but other waveguides may also be used in the waveguide member  130 . 
         [0037]    The waveguide member  130  includes a mirror  131  that is arranged at a position opposite the light-receiving device  111 . The mirror  131  is, for example, formed by notching the waveguide member  130  through dicing or laser beam machining. The inclination angle of the mirror  131  is, for example, 45°. For this reason, the mirror  131  is able to bend light that is transported in the waveguide member  130  and light that is incident in the waveguide member  130  at 90°. Accordingly, not only is the traveling direction of the light transported in the waveguide member  130  bent at 90° so that the light is able to be emitted to the light-receiving device  111 , but the traveling direction of the light emitted from the light-emitting device  112  is also bent at 90° so that the light is able to be transported in the waveguide member  130 . 
         [0038]      FIG. 3  is an enlarged partial cross-sectional view taken along line III-III of  FIG. 1 . As illustrated in  FIG. 3 , the optical board  103  has an open part that corresponds to an optical path K through which light is transmitted. The optical board  103  may not have an open part that corresponds to the optical path K provided that light-transmissive transparent materials are used. 
         [0039]    The light-receiving device  111  includes the light-receiving portion  111   a  and terminals  111   b . Arranged toward the lens sheet  120  side, the light-receiving portion  111   a  is mounted face down and receives light that is transmitted through the lens sheet  120 . The light-receiving device  111  converts the received light into a signal current. The light-receiving portion  111   a  is, for example, formed to have a circular shape. The terminals  111   b  are connected to the optical board  103  and transports the signal current to the connected optical board  103 . 
         [0040]    Although not illustrated, the light-emitting device  112  includes the light-emitting portion and terminals. Arranged toward the lens sheet  120  side similarly to the light-receiving portion  111   a , the light-emitting portion is mounted face down and outputs light toward the lens sheet  120 . The light-emitting device  112  converts an input signal current into light. The light-emitting portion is, for example, formed to have a circular shape. In addition, the terminals of the light-emitting device  112  are connected to the optical board  103  and transports the signal current to the connected optical board  103 . 
         [0041]    The board adhesive sheet  125  bonds the optical board  103  and the lens sheet  120 . The board adhesive sheet  125  has an opening portion that is formed at a position corresponding to the optical path K so that light is able to be transmitted from the optical board  103  to the lens sheet  120 . The board adhesive sheet  125  has, for example, a thickness of 25 μm. 
         [0042]    The lens sheet  120  is a transparent member. For example, a thermoplastic resin such as a cyclic olefin polymer (COP) and polycarbonate (PC) is used in the lens sheet  120 . The lens sheet  120  has, for example, a thickness of 60 μm. 
         [0043]    The lens portion  120   a  for condensing light is formed in the lens sheet  120 . The lens portion  120   a  transmits light emitted from the light-emitting device  112  and light emitted by the waveguide member  130 . The lens portion  120   a  illustrated in  FIG. 3  is, for example, a convex lens that has a predetermined height. The lens portion  120   a  is not limited to a convex lens but may be a concave lens. 
         [0044]    The bonding layer  127  is a layer for bonding in which an adhesive sheet  127   a  that bonds the lens portion  120   a  and the waveguide member  130  is arranged with a gap  128  disposed therein. The gap  128  allows light transmitted through the lens portion  120   a  to pass to the waveguide member  130  and allows light emitted by the waveguide member  130  to pass to the lens portion  120   a . For example, the gap  128  may be formed by disposing an opening portion in an area that includes the optical path K between the lens portion  120   a  and the waveguide member  130  in the adhesive sheet  127   a.    
         [0045]    The adhesive sheet  127   a  is arranged in an area other than the gap  128  that includes the optical path K between the lens portion  120   a  and the waveguide member  130  and bonds the lens sheet  120  and the waveguide member  130 . Specifically, the adhesive sheet  127   a  is a sheet that has an adhesiveness on the surfaces thereof and bonds the lens sheet  120  and the waveguide member  130 . The adhesive sheet  127   a  is formed in advance to have a uniform thickness (for example, 25 μm), and, for example, a sheet with a thickness variation of 2 μm or less is used as the adhesive sheet  127   a.    
         [0046]    In addition, a sheet with sufficiently small thickness change caused by pressurization with respect to the distance between the lens and the mirror or a sheet of which the thickness changes to be proportional to a pressure is used as the adhesive sheet  127   a . A thermosetting adhesive sheet or an ultraviolet-curable adhesive sheet is used as the adhesive sheet  127   a . The thermosetting adhesive sheet bonds the lens sheet  120  and the waveguide member  130  by the adhesive surfaces thereof being cured by heating. The ultraviolet-curable adhesive sheet bonds the lens sheet  120  and the waveguide member  130  by the adhesive surfaces thereof being cured by ultraviolet radiation. 
         [0047]    In addition, the adhesive sheet  127   a  may not have a light transmissivity since arranged on an area where light is not transmitted through other than the gap  128 . For this reason, even without considering the transmissivity, the adhesive sheet  127   a  selected based only on the thickness, the thickness uniformity, and the adhesiveness thereof may be used. 
         [0048]    The light-transmissive resin  127   b  forms a transmissive portion  129  that transmits light by filling the gap  128  with a liquid-state light-transmissive resin. Specifically, the light-transmissive resin  127   b  is a liquid-state light-transmissive resin. Liquid state specifically means a liquid that has fluidity. The light-transmissive resin  127   b , for example, has a viscosity of 1000 cP or less. 
         [0049]    For example, the light-transmissive resin  127   b  is an adhesive resin that bonds the lens sheet  120  and the waveguide member  130 . Accordingly, occurrence of voids is suppressed by closely bonding the light-transmissive resin  127   b  and the lens sheet  120 , and the light-transmissive resin  127   b  and the waveguide member  130 . A thermosetting adhesive resin that is cured by heating or an ultraviolet-curable adhesive resin that is cured by ultraviolet radiation is used as the light-transmissive resin  127   b.    
         [0050]    According to such a configuration, the optical transceiver  100  is able to condense light that is output from other optical transceivers  100  in the light-receiving portion  111   a . In addition, the optical transceiver  100  is able to output light that is emitted from the light-emitting device  112 , which is not illustrated, from the waveguide member  130  to other optical transceivers  100 . 
         [0051]    In addition, an optical module for receiving light is able to be realized by the optical board  103 , the light-receiving device  111 , the lens sheet  120 , the board adhesive sheet  125 , the bonding layer  127 , the waveguide member  130 , and the transmissive portion  129 . In addition, an optical module for emitting light is able to be realized by the optical board  103 , the light-emitting device  112 , the lens sheet  120 , the board adhesive sheet  125 , the bonding layer  127 , the waveguide member  130 , and the transmissive portion  129 . 
         [0052]    The optical transceiver  100  has both an optical module that includes the light-receiving device  111  and an optical module that includes the light-emitting device  112  mounted thereon. The lens sheet  120  is formed by integrating the lens portion  120   a  that transmits light to the light-receiving device  111  with the lens portion  120   a  that transmits light from the light-emitting device  112 . In addition, the waveguide member  130  is formed by integrating an optical waveguide (the core  130   a  and the cladding  130   b ) that transports light to the light-receiving device  111  with an optical waveguide (the core  130   a  and the cladding  130   b ) that transports light from the light-emitting device  112 . 
         [0053]    In addition, the transmissive portion  129  is formed by integrating the transmissive portion  129  that transmits light to the light-receiving device  111  with the transmissive portion  129  that transmits light from the light-emitting device  112 . In addition, the bonding layer  127  is formed by integrating the bonding layer  127  of a forming body for receiving light with the bonding layer  127  of a forming body for emitting light. The forming body for receiving light is the lens sheet  120  that includes the lens portion  120   a  which transmits light to the light-receiving device  111  and the waveguide member  130  that transports light to the light-receiving device  111 . The forming body for emitting light is formed by integrating the lens sheet  120  that includes the lens portion  120   a  which transmits light from the light-emitting device  112  with the bonding layer  127  that bonds the waveguide member  130  which transports light from the light-emitting device  112 . 
         [0054]    Regarding One Example of Manufacturing Process of Optical Transceiver 
         [0055]    Next, one example of the manufacturing process of the optical transceiver will be described using  FIGS. 4 to 6 .  FIG. 4  is a flow chart illustrating one example of the manufacturing process of the optical transceiver. In the manufacturing process of the optical transceiver  100  illustrated in  FIG. 4 , a process of attaching the adhesive sheet  127   a  to the waveguide member  130  is first performed (step S 401 ). 
         [0056]    Next, a process of bonding the waveguide member  130  and the lens sheet  120  is performed by attaching the lens sheet  120  to the adhesive sheet  127   a  to which the waveguide member  130  is attached in step S 401  (step S 402 ). 
         [0057]    Next, a process of filling the gap  128  with the light-transmissive resin  127   b , to which the adhesive sheet  127   a  is not attached, in the forming body of the waveguide member  130 , the lens sheet  120 , and the adhesive sheet  127   a  that are integrated with each other in step S 402  is performed (step S 403 ). 
         [0058]    Next, a process of curing the light-transmissive resin  127   b  that is filled in step S 403  is performed (step S 404 ). In step S 404 , heating or ultraviolet radiation is performed according to the type of the adhesive sheet  127   a  and the light-transmissive resin  127   b  used. 
         [0059]    Then, a process of attaching the board adhesive sheet  125  to the lens sheet  120  among the forming body of the waveguide member  130 , the lens sheet  120 , the adhesive sheet  127   a , and the light-transmissive resin  127   b  is performed (step S 405 ). Next, a process of bonding the forming body and the optical board  103  by attaching the optical board  103  to the board adhesive sheet  125  that is attached to the forming body is performed (step S 406 ), and the manufacturing process according to this flow chart ends. 
         [0060]    The adhesive sheet  127   a  is first attached to the waveguide member  130  (refer to step S 401 ), and the lens sheet  120  is attached thereafter (refer to step S 402 ) in the flow chart described above. However, the process order of step S 401  and step S 402  may be reversed. 
         [0061]      FIG. 5  is a description diagram (part  1 ) illustrating one example of the manufacturing process of the optical transceiver according to the first embodiment.  FIG. 6  is a description diagram (part  2 ) illustrating one example of the manufacturing process of the optical transceiver according to the first embodiment. As illustrated in  FIG. 5 , first, (1) attach the adhesive sheet  127   a  to the waveguide member  130 . At this time, the adhesive sheet  127   a  is attached to the waveguide member  130  while the gap  128  is secured. 
         [0062]    Next, (2) attach the lens sheet  120  to the adhesive sheet  127   a  that is attached to the waveguide member  130 . Accordingly, the waveguide member  130  and the lens sheet  120  are bonded together. At this time, a predetermined pressure (for example, maximum 0.1 MPa to 0.5 MPa) is used in pressurizing the waveguide member  130  and the lens sheet  120  since the angle of the mirror  131  of the waveguide member  130  is deformed when the pressure is high. 
         [0063]    Then, (3) fill the gap  128  with the light-transmissive resin  127   b , to which the adhesive sheet  127   a  is not attached. At this time, the light-transmissive resin  127   b  is able to be injected into the gap  128  without flowing to the places other than the gap  128  since the gap  128  is formed by the adhesive sheet  127   a.    
         [0064]    Here, an opening  128   k  is disposed on a side of the gap  128  that is opposite the side from which the light-transmissive resin  127   b  is injected. Specifically, the gap  128  is disposed so as to penetrate the forming body that includes the bonding layer  127 , the lens sheet  120 , and the waveguide member  130  which are bonded with the bonding layer  127 . Accordingly, the light-transmissive resin  127   b  is able to be injected in one direction from one side, and air inside the gap  128  is able to be efficiently discharged by injecting the light-transmissive resin  127   b . For this reason, the light-transmissive resin  127   b  is able to be injected without gaps, and occurrence of voids is able to be suppressed. 
         [0065]    Then, as illustrated in  FIG. 6 , (4) perform ultraviolet (UV) radiation or heating process according to the type of the adhesive sheet  127   a  and the light-transmissive resin  127   b  used. Accordingly, the adhesive sheet  127   a  and the light-transmissive resin  127   b  are cured. 
         [0066]    Then, (5) attach the board adhesive sheet  125  to the upper surface of the lens sheet  120 . At this time, the board adhesive sheet  125  is not attached to the area around the lens portion  120   a  so as to secure the optical path K. Next, (6) bond the optical board  103  to the forming body by attaching the optical board  103  to the board adhesive sheet  125 . Accordingly, the optical transceiver  100  is able to be manufactured. 
         [0067]    Relationship Between Thickness of Adhesive Sheet and Filling Failure of Light-Transmissive Resin 
         [0068]      FIG. 7  is a graph illustrating the relationship between the thickness of the adhesive sheet and filling failure of the light-transmissive resin. In  FIG. 7 , the horizontal axis indicates the thickness of the adhesive sheet  127   a , and the vertical axis indicates the failure rate of the light-transmissive resin  127   b . Failure of the light-transmissive resin  127   b  means that the light-transmissive resin  127   b  does not flow and stops and the gap  128  is not properly filled, thereby causing voids to occur. Specifically, the failure rate of the light-transmissive resin  127   b  indicates the occurrence rate of voids. The viscosity of the light-transmissive resin  127   b  is, for example, 1000 cP or less. 
         [0069]    As illustrated in relationship  700 , the failure rate is 0% when the thickness of the adhesive sheet  127   a  is 20 μm, 25 μm, 35 μm, or 50 μm. That is, this indicates voids do not occur in all the manufactured optical transceivers  100 . 
         [0070]    Meanwhile, the failure rate is 80% when the thickness of the adhesive sheet  127   a  is 10 μm. The failure rate being 80%, for example, indicates voids do not occur in only one sample while occurring in four other samples given that the number of samples is five. 
         [0071]    The failure rate is 40% when the thickness of the adhesive sheet  127   a  is 15 μm. The failure rate being 40%, for example, indicates that voids do not occur in three samples while occurring in two other samples given that the number of samples is five. 
         [0072]    Accordingly, by setting the thickness of the adhesive sheet  127   a  to be within 20 μm to 50 μm, the light-transmissive resin  127   b  is able to be injected into the gap  128  without gaps with respect to all the manufactured optical transceivers  100 . Therefore, occurrence of voids is able to be suppressed. 
         [0073]    Focal Point of Light 
         [0074]    Next, the focal point of light will be described using  FIG. 8 ,  FIG. 9A , and  FIG. 9B .  FIG. 8  is a description diagram illustrating the focal point of light in the optical transceiver according to the first embodiment. As illustrated in  FIG. 8 , the focal point of light of the optical transceiver  100  according to the first embodiment is consistent with a focal point  800  in the design of the optical transceiver. Specifically, the optical transceiver  100  is able to suppress occurrence of voids since the light-transmissive resin  127   b  is injected into the gap  128 . Accordingly, the inconsistency between the position of the focal point and the focal point  800  in the design caused by occurrence of voids (refer to  FIG. 9A ) is able to be suppressed, and the position of the focal point is able to be set at the same position as that of the focal point  800  in the design. For this reason, the optical transceiver  100  is able to suppress optical loss. 
         [0075]    In addition, the optical transceiver  100  uses the adhesive sheet  127   a  of which the thickness variation is small and is able to make the variations in the distance between the lens portion  120   a  and the mirror  131  small (for example, ≦±10 μm). For this reason, the optical transceiver  100  is able to suppress the inconsistency between the position of the focal point and the focal point  800  in the design caused by the thickness of the bonding layer  127  being different from the allowable thickness in the design (refer to  FIG. 9B ). That is, the optical transceiver  100  is able to set the thickness of the bonding layer  127  to be the allowable thickness in the design and is able to set the position of the focal point to be the same position as that of the focal point  800  in the design. For this reason, the optical transceiver  100  is able to suppress optical loss. 
         [0076]      FIG. 9A  is a description diagram (part  1 ) illustrating the focal point of light in an optical transceiver of the related art. The optical transceiver of the related art, for example, uses the bonding layer  127  with the light-transmissive resin  127   b  layer formed on the whole surfaces of the bonding layer  127 . The light-transmissive resin  127   b  is applied to the whole surfaces of the bonding layer  127  in the manufacture of the optical transceiver of the related art. However, as illustrated in  FIG. 9A , voids  901  occur depending on the application method or the application amount when applying the light-transmissive resin  127   b . When the voids  901  occur on the optical path K, the refractive index of light changes in the voids  901 , and the position of a focal point  900  differs from that of the focal point  800  in the design. Accordingly, optical loss occurs. 
         [0077]    On the other hand, the occurrence of the voids  901  may be suppressed by increasing the pressure when bonding the waveguide member  130  and the lens sheet  120  in the manufacture of the optical transceiver. However, the mirror  131  deforms when the pressure increases, so the pressure does not actually increase. 
         [0078]    In addition, assume a configuration in which the gap  128  is not disposed, and the transmissive adhesive sheet  127   a  is also inserted into the transmissive portion  129  where the light-transmissive resin  127   b  is injected. In this configuration, gaps occur between the lens sheet  120  and the adhesive sheet  127   a  when the adhesive sheet  127   a  in the transmissive portion  129  has a waviness on the surface that adheres to the lens sheet  120 . As a consequence, voids occur. Accordingly, in the configuration in which the transmissive adhesive sheet  127   a  is inserted into the transmissive portion  129 , the position of the focal point differs from that of the focal point  800  in the design similar to the focal point of light in the optical transceiver of the related art illustrated in  FIG. 9A . 
         [0079]    On the contrary, the optical transceiver  100  according to the first embodiment is able to fill the gap  128  with the light-transmissive resin  127   b  by injecting the light-transmissive resin  127   b  into the gap  128 . Therefore, occurrence of voids in the transmissive portion  129  is able to be suppressed. For this reason, the position of the focal point is able to be consistent with the focal point  800  in the design, and optical loss is able to be suppressed. 
         [0080]      FIG. 9B  is a description diagram (part  2 ) illustrating the focal point of light in the optical transceiver of the related art. The optical transceiver of the related art, for example, uses the bonding layer  127  with the light-transmissive resin  127   b  layer formed on the whole surfaces of the bonding layer  127 . The waveguide member  130  and the lens sheet  120  are pressurized when bonded in the manufacture of the optical transceiver of the related art. At this time, the distance between the lens portion  120   a  and the mirror  131  may be an unallowable thickness depending on the application amount and the application method of the light-transmissive resin  127   b  that is applied to the whole surfaces of the bonding layer  127  and the pressure during the application. 
         [0081]    Specifically, the variation in the distance between the lens portion  120   a  and the mirror  131  is ±10 μm or less in the optical transceiver  100  according to the first embodiment but is approximately ±20 μm in the configuration of the related art in which the light-transmissive resin  127   b  is applied to the whole surfaces of the bonding layer  127 . Accordingly, the distance between the lens portion  120   a  and the mirror  131  changes when the thickness variation of the bonding layer  127  increases. Thus, the position of a focal point  920  differs from the focal point  800  in the design. Therefore, optical loss occurs. 
         [0082]    Meanwhile, assuming a configuration in which the gap  128  is not filled with the light-transmissive resin  127   b  to be an air layer, for example, flexure occurs in the lens sheet  120 , so the distance between the lens portion  120   a  and the mirror  131  changes. Therefore, the position of the focal point changes, and optical loss occurs. 
         [0083]    On the contrary, the optical transceiver  100  according to the first embodiment is able to set the thickness of the bonding layer  127  to be the allowable thickness in the design by using the adhesive sheet  127   a  and is able to set the distance between the lens portion  120   a  and the mirror  131  to be consistent. For this reason, the position of the focal point is able to be set at the same position as that of the focal point  800  in the design, and optical loss is able to be suppressed. 
         [0084]    In the first embodiment hereinbefore, the gap  128  is disposed in the part where light passes in the bonding layer  127  that bonds the lens sheet  120  and the waveguide member  130  with the adhesive sheet  127   a , and the liquid-state light-transmissive resin  127   b  is injected into the gap  128  to form the transmissive portion  129 . Accordingly, occurrence of voids is able to be suppressed in the transmissive portion  129 , and optical loss is able to be suppressed. 
       Modification Example of First Embodiment 
       [0085]      FIG. 10  is a description diagram illustrating a modification example of the first embodiment. The modification example illustrated in  FIG. 10  differs from the first embodiment in that the opening  128   k  (refer to  FIG. 5 ) is not disposed on the side of the gap  128  that is opposite the side from which the light-transmissive resin  127   b  is injected, but a barrier  120   c  is formed. Specifically, the gap  128  is not configured to penetrate the forming body that includes the bonding layer  127 , the lens sheet  120 , and the waveguide member  130  which are bonded with the bonding layer  127  in the modification example. In the modification example, the same places as the places described in the first embodiment will be given the same reference signs and will not be described. 
         [0086]    The barrier  120   c  is formed by a part of the lens sheet  120  and bonds the lens sheet  120  and the waveguide member  130 . The barrier  120   c  is arranged at a position where the optical path K avoids. In the modification example, the adhesion strength between the lens sheet  120  and the waveguide member  130  is able to be increased at a stage prior to injecting the light-transmissive resin  127   b . Therefore, manufacturing efficiency is able to be improved. In addition, the thickness of the bonding layer  127  in the transmissive portion  129  is able to be set further closer to the thickness of the adhesive sheet  127   a  in the modification example. 
         [0087]    According to such a modification example, like in the first embodiment, occurrence of voids is able to be suppressed, and the thickness of the bonding layer  127  is able to be set to the allowable thickness in the design. Therefore, optical loss is able to be suppressed. 
       Second Embodiment 
       [0088]      FIG. 11  is a description diagram illustrating an optical module of an optical transceiver according to a second embodiment. In the second embodiment, a configuration in which the adhesive sheet  127   a  is not used, and an interposed member (standoff) that adjusts the height of a layer between the lens portion  120   a  and the waveguide member  130  is used will be described. In the second embodiment, the same places as the places described in the first embodiment will be given the same reference signs and will not be described. 
         [0089]    As illustrated in  FIG. 11 , a standoff  120   b  is arranged while a first gap  128   a  that allows light on the optical path K to pass therethrough and a second gap  128   b  which differs from the first gap  128   a  are disposed between the lens sheet  120  and the waveguide member  130 . Specifically, the standoff  120   b  is arranged in an area other than the first gap  128   a  that includes the optical path K between the lens portion  120   a  and the waveguide member  130  and abuts on the surface of the lens sheet  120  and on the surfaces of the waveguide member  130 . The standoff  120   b  has a consistent thickness (for example, 25 μm). 
         [0090]    For example, the standoff  120   b  is disposed in the lens sheet  120 . Specifically, a plurality of standoffs  120   b  is formed on a side of the lens sheet  120  that is opposite the side where the lens portion  120   a  is formed. The plurality of standoffs  120   b  each has an elliptic shape (refer to (2) in  FIG. 12 ) and is separately arranged while the longitudinal direction thereof is aligned to one direction (y direction in  FIG. 11 ). The plurality of standoffs  120   b  each has a uniform thickness. 
         [0091]    The thickness of the standoff  120   b  is, for example, the same as the thickness of the adhesive sheet  127   a  illustrated in the first embodiment. Accordingly, the standoff  120   b  is able to secure a consistent distance (thickness) between the lens sheet  120  and the waveguide member  130 , and change in the position of the focal point is able to be suppressed. 
         [0092]    The standoff  120   b  is formed into an elliptic cylinder shape. The standoff  120   b  is formed in the manufacturing process of the lens portion  120   a . Specifically, the lens portion  120   a  and the standoff  120   b  are able to be simultaneously formed in the manufacturing process of the lens portion  120   a  by using a die that is modeled on the lens portion  120   a  and the standoff  120   b.    
         [0093]    The light-transmissive resin  127   b  is injected into the first gap  128   a  for securing the optical path K and the second gap  128   b  between each of the standoffs  120   b  to bond the lens sheet  120  and the waveguide member  130 . Injecting the liquid-state light-transmissive resin  127   b  into the first gap  128   a  forms the transmissive portion  129 . In addition, injecting the liquid-state light-transmissive resin  127   b  into the second gap  128   b  forms a bonding portion that bonds the lens sheet  120  and the waveguide member  130 . 
         [0094]      FIG. 12  is a description diagram (part  1 ) illustrating one example of the manufacturing process of the optical transceiver according to the second embodiment.  FIG. 13  is a description diagram (part  2 ) illustrating one example of the manufacturing process of the optical transceiver according to the second embodiment. As illustrated in  FIG. 12 , first, (1) overlay the lens sheet  120  on the waveguide member  130 . At this time, the optical path K is secured by the lens portion  120   a  being opposite the mirror  131 . 
         [0095]    Next, (2) inject the light-transmissive resin  127   b  into the first gap  128   a  and the second gap  128   b . At this time, the light-transmissive resin  127   b  is injected from one side in the same direction as the longitudinal direction of the ellipse (direction of the minor axis projection plane) of the standoff  120   b . Accordingly, the light-transmissive resin  127   b  is able to be injected in a streamlined manner, and the light-transmissive resin  127   b  is able to be efficiently injected since the light-transmissive resin  127   b  efficiently flows. Specifically, the light-transmissive resin  127   b  is able to easily detour around the rear side (opposite side in the injecting direction) of each standoff  120   b  to flow into the second gap  128   b.    
         [0096]    In addition, in injecting the light-transmissive resin  127   b , the light-transmissive resin  127   b  is injected while the opening  128   k  is disposed on a side of the lens sheet  120  that is opposite the side from which the light-transmissive resin  127   b  is injected. For this reason, the light-transmissive resin  127   b  is able to be injected without gaps, and occurrence of voids is able to be suppressed. 
         [0097]    The resin injected into the second gap  128   b  is not limited to the light-transmissive resin  127   b . Resins not having transmissivity may be also used provided that the resin is a liquid-state adhesive resin that is able to bond the lens sheet  120  and the waveguide member  130 . Specifically, the first gap  128   a  may be filled with the light-transmissive resin  127   b , and the second gap  128   b  may be filled with resin (adhesive) that does not have light transmissivity since light is not transmitted in the second gap  128   b . In addition, even voids occurring in the second gap  128   b  do not intervene on the optical path K. However, it is better for voids to not occur in the second gap  128   b  from the perspective of increasing the adhesion strength between the lens sheet  120  and the waveguide member  130 . 
         [0098]    Next, as illustrated in  FIG. 13 , (3) cure the light-transmissive resin  127   b  by UV radiation or by heating depending on the type of the light-transmissive resin  127   b  used. Then, (4) attach the board adhesive sheet  125  to the upper surface of the lens sheet  120 . At this time, the board adhesive sheet  125  is not attached to the area around the lens portion  120   a  to secure the optical path K. Next, (5) bond the optical board  103  to the forming body by attaching the optical board  103  to the board adhesive sheet  125 . Accordingly, the optical transceiver  100  according to the second embodiment is able to be manufactured. 
         [0099]    In the second embodiment, the standoff  120   b  is integrated with the lens sheet  120  but may be also integrated with the waveguide member  130  or may be disposed on another member other than the lens sheet  120  and the waveguide member  130 . In addition, the shape of the standoff  120   b  is not limited to an elliptic cylinder shape but may be other shapes such as a square pillar shape. 
         [0100]    In addition, the relationship between the thickness of the adhesive sheet  127   a  and filling failure of the light-transmissive resin  127   b  illustrated in  FIG. 7  may be represented as the relationship between the height of the standoff  120   b  and filling failure of the light-transmissive resin  127   b  in the second embodiment. Specifically, the failure rate is 0% when the height of the standoff  120   b  is 20 μm, 25 μm, 35 μm, or 50 μm. That is, voids do not occur in all the manufactured optical transceivers  100 . 
         [0101]    As described above, the optical transceiver  100  according to the second embodiment is able to suppress occurrence of voids by injecting the light-transmissive resin  127   b  alike the first embodiment. In addition, the thickness of the bonding layer  127  is able to be set to the allowable thickness in the design by the standoff  120   b . Accordingly, the position of the focal point is able to be set to the same position as that of the focal point  800  in the design (refer to  FIG. 8 ). Therefore, optical loss is able to be suppressed. 
       Modification Example of Second Embodiment 
       [0102]      FIG. 14  is a description diagram illustrating a modification example of the second embodiment. The modification example illustrated in  FIG. 14  differs from the second embodiment in that the plurality of standoffs (interposed members) is not configured to be scattered, but linear standoffs that line up and extend from the side from which the light-transmissive resin  127   b  is injected into the opposite side are used. 
         [0103]    In  FIG. 14 , a standoff  120   d , for example, is plurally formed on a side of the lens sheet  120  that is opposite the side where the lens portion  120   a  is formed. The plurality of standoffs  120   d  is linearly formed, lines up, and extends from the injecting side to the opposite side and is separately arranged while the longitudinal direction thereof is aligned to one direction. Each standoff  120   d  has a uniform thickness. 
         [0104]    The light-transmissive resin  127   b  is suitably injected from one side in the same direction as the longitudinal direction of the standoff  120   d  when injecting the light-transmissive resin  127   b  into the first gap  128   a  and the second gap  128   b . In such a configuration, also, the light-transmissive resin  127   b  is able to be injected into the first gap  128   a  and the second gap  128   b , and occurrence of voids is able to be suppressed. 
         [0105]    In addition, like in the second embodiment, the consistent distance (thickness) between the lens sheet  120  and the waveguide member  130  is able to be secured, and change in the position of the focal point is able to be suppressed. 
         [0106]    All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.