Abstract:
This optical receptacle has first optical surfaces via which light outputted by respective light-emitting elements is inputted, a second optical surface whereby light inputted via said first optical surfaces is outputted towards an end face of a light-transporting body, a third optical surface whereby light inputted via the first optical surfaces is reflected towards the second optical surface, a plurality of first concavities formed in the surface where the second optical surface is located, and a plurality of second concavities formed in the surface where the first optical surfaces are located or a surface opposite the surface where the first concavities are located. The first concavities and the second concavities are laid out opposite each other so that the central axes thereof coincide.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an optical receptacle and an optical module including the optical receptacle. 
       BACKGROUND ART 
       [0002]    In optical communications using optical transmission members such as optical fibers and light waveguides, optical modules have been used, provided with a light emitting element such as a surface-emitting laser (for example, VCSEL: Vertical Cavity Surface Emitting Laser). Such an optical module includes a transmitting optical receptacle that allows light including communication information emitted from a light emitting element to be incident on an optical transmission member, or a receiving optical receptacle that allows light from the optical transmission member to be incident on a light receiving element (see, e.g., PTL 1). 
         [0003]      FIG. 1  is a perspective view of receiving optical receptacle  10  disclosed in PTL 1. As illustrated in  FIG. 1 , optical receptacle  10  includes a plurality of incidence surfaces  12  that allow light from a plurality of optical fibers to be respectively incident thereon, reflection surface  14  that reflects light incident on the plurality of incidence surfaces  12 , a plurality of emission surfaces  16  that emit light reflected by reflection surface  14  respectively toward the plurality of light receiving elements, and a pair of guide holes  18  disposed such that reflection surface  14  is interposed therebetween. The plurality of optical fibers are housed in an optical connector, and convex parts of the optical connector are inserted into guide holes  18  to thereby connect the plurality of optical fibers to optical receptacle  10 . 
         [0004]    In optical receptacle  10  connected in such a manner, light emitted from the optical fiber is incident on incidence surface  12  to be reflected by reflection surface  14  toward the light receiving surface of the light receiving element, and then reaches the light receiving surface of the light receiving element through light emission surface  16 . 
         [0005]    Optical receptacle  10  disclosed in PTL 1 is integrally molded by injection molding using a thermoplastic transparent resin. Specifically, optical receptacle  10  is produced by pouring the thermoplastic transparent resin into a mold cavity for solidification, and then releasing optical receptacle  10 . 
       CITATION LIST 
     Patent Literature 
       [0006]    PTL 1: Japanese Patent Application Laid-Open No. 2005-031556 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0007]    However, when optical receptacle  10  disclosed in PTL 1 is produced by injection molding, mold portions corresponding to guide holes  18  are not easily extracted from guide holes  18 , and thus optical receptacle  10  is undesirably deformed during releasing. Optical receptacle  10  having been deformed during releasing cannot return to the shape before releasing, and thus is unable to properly guide the light emitted from the optical fibers to the light receiving surface of the light receiving element in some cases. Thus, optical receptacle  10  disclosed in PTL 1 has a problem of being deformed when produced by injection molding. 
         [0008]    An object of the present invention is to provide an optical receptacle which is not easily deformed even when produced by injection molding. Further, another object of the present invention is to provide an optical module having the optical receptacle. 
       Solution to Problem 
       [0009]    An optical receptacle of the present invention is disposed between a plurality of light emitting elements or a plurality of light receiving elements and a plurality of optical transmission members, and is configured to optically couple the light emitting elements or the light receiving elements to end surfaces of the optical transmission members, respectively, the optical receptacle including: a plurality of first optical surfaces, each configured such that light emitted from a corresponding one of the light emitting elements is incident on the first optical surface or each configured to emit light propagating therein toward a corresponding one of the light receiving elements; a plurality of second optical surfaces, each configured to emit the light incident on the first optical surface toward an end surface of a corresponding one of the optical transmission members or each configured such that light from a corresponding one of the optical transmission members is incident on the second optical surface; a third optical surface configured to reflect the light incident on the first optical surface toward the second optical surface or configured to reflect the light incident on the second optical surface toward the first optical surface; a plurality of first recesses formed on a surface on which the plurality of second optical surfaces are disposed or a surface on which the plurality of first optical surfaces are disposed; and a plurality of second recesses formed on a surface opposite to a surface on which the first recesses are disposed, in which the plurality of first recesses and the plurality of second recesses are disposed opposite to each other such that central axes of the first recesses coincide, respectively, with central axes of the second recesses. 
         [0010]    Further, an optical receptacle of the present invention is disposed between a plurality of light emitting elements or a plurality of light receiving elements and a plurality of optical transmission members, and is configured to optically couple the light emitting elements or the light receiving elements to end surfaces of the optical transmission members, respectively, the optical receptacle including: a plurality of first optical surfaces, each configured such that light emitted from a corresponding one of the light emitting elements is incident on the first optical surface or each configured to emit light propagating therein toward a corresponding one of the light receiving elements; a plurality of second optical surfaces, each configured to emit the light incident on the first optical surface toward an end surface of a corresponding one of the optical transmission members or each configured such that light from a corresponding one of the optical transmission members is incident on the second optical surface; a third optical surface configured to reflect the light incident on the first optical surface toward the second optical surface or configured to reflect the light incident on the second optical surface toward the first optical surface; and a plurality of recesses formed on a surface on which the plurality of second optical surfaces are disposed, in which each of the plurality of recesses includes a cylindrical recess body and a substantially truncated cone-shaped tapered part formed continuously to a bottom of the recess body. 
         [0011]    An optical module of the present invention includes: a substrate on which a plurality of light emitting elements or a plurality of light receiving elements are disposed; and the optical receptacle of the present invention disposed on the substrate. 
       Advantageous Effects of Invention 
       [0012]    According to the present invention, a plurality of light emitting elements or a plurality of light receiving elements can be optically coupled suitably to a plurality of optical transmission members even when an optical receptacle is produced by injection molding. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0013]      FIG. 1  is a perspective view of an optical receptacle according to PTL 1; 
           [0014]      FIG. 2  is a cross-sectional view of an optical module according to Embodiment 1; 
           [0015]      FIGS. 3A to 3E  illustrate a configuration of an optical receptacle according to Embodiment 1; 
           [0016]      FIGS. 4A to 4E  illustrate a configuration of an optical receptacle of a comparative example; 
           [0017]      FIGS. 5A and 5B  are explanatory diagrams of distortion of the optical receptacle of the comparative example; 
           [0018]      FIGS. 6A and 6B  are explanatory diagrams of distortion of the optical receptacle according to Embodiment 1; 
           [0019]      FIGS. 7A to 7E  illustrate a configuration of an optical receptacle according to Embodiment 2; and 
           [0020]      FIGS. 8A and 8B  are explanatory diagrams of distortion of the optical receptacle according to Embodiment 2. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0021]    Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       Embodiment 1 
     Configuration of Optical Module 
       [0022]      FIG. 2  is a cross-sectional view of optical module  100  according to Embodiment 1 of the present invention. In  FIG. 2 , hatching is omitted in the cross-section of optical receptacle  120  to show an optical path in optical receptacle  120 . 
         [0023]    As illustrated in  FIG. 2 , optical module  100  includes substrate-mounted photoelectric conversion device  110  including light emitting elements  114 , and optical receptacle  120 . Optical module  100  is used with optical receptacle  120  connected to optical transmission members  116 . Optical transmission member  116  is not limited to any particular type and may be an optical fiber or a light waveguide, for example. In the present embodiment, optical transmission member  116  is an optical fiber. Further, the optical fiber may be a single-mode optical fiber or a multi-mode optical fiber. 
         [0024]    Photoelectric conversion device  110  includes substrate  112  and a plurality of light emitting elements  114 . Light emitting elements  114  are disposed in line on substrate  112 , and configured to emit laser light in the direction perpendicular to the surface of substrate  112 . Light emitting element  114  is, e.g., Vertical Cavity Surface Emitting Laser (VCSEL). 
         [0025]    Optical receptacle  120  optically couples light emitting elements  114  to the end surfaces of optical transmission members  116 , in the state of being disposed between photoelectric conversion device  110  and optical transmission members  116 . A configuration of optical receptacle  120  is described in detail below. 
         [0026]    (Configuration of Optical Receptacle) 
         [0027]      FIGS. 3A to 3E  illustrate a configuration of optical receptacle  120  according to Embodiment 1.  FIGS. 3A to 3E  are a plan view, a bottom view, a front view, a rear view and a right side view of optical receptacle  120 , respectively. 
         [0028]    As illustrated in  FIGS. 3A to 3E , optical receptacle  120  is a substantially rectangular parallelepiped member. Optical receptacle  120  is light transmissive, and configured to emit light emitted from light emitting element  114  toward the end surface of optical transmission member  116 . Optical receptacle  120  includes a plurality of first optical surfaces (incidence surfaces)  121 , third optical surface (reflection surface)  122 , a plurality of second optical surfaces (emission surfaces)  123 , a plurality of first recesses  124 , and a plurality of second recesses  125 . Optical receptacle  120  is formed of a light-transmissive material with respect to light having a wavelength used for optical communications. Examples of the materials include transparent resins such as polyetherimide (PEI) and cyclic olefin resins. Optical receptacle  120  can be produced by injection molding, for example. 
         [0029]    First optical surface  121  is an incidence surface that refracts laser light emitted from light emitting element  114  to allow the light to enter inside optical receptacle  120 . A plurality of first optical surfaces  121  are disposed in line in the lengthwise direction on the bottom surface of optical receptacle  120  so as to face respective light emitting elements  114 . The shape of first optical surface  121  is not particularly limited. In the present embodiment, the shape of first optical surface  121  is that of a convex lens surface protruding toward light emitting element  114 . The shape of first optical surface  121  in plan view is a circle. The central axis of first optical surface  121  is preferably perpendicular to the light emitting surface of light emitting element  114  (and to the surface of substrate  112 ). Further, the central axis of first optical surface  121  preferably coincides with the optical axis of the laser light emitted from light emitting element  114 . The light incident on first optical surface  121  (incidence surface) propagates toward third optical surface  122  (reflection surface). 
         [0030]    Third optical surface  122  is a reflection surface that reflects the light incident on first optical surface  121  toward second optical surface  123 . Third optical surface  122  is tilted such that the distance from optical transmission member  116  decreases in the direction from the bottom surface to the top surface of optical receptacle  120 . The inclination angle of third optical surface  122  relative to the optical axis of light emitted from light emitting element  114  is not particularly limited. In the present embodiment, the inclination angle of third optical surface  122  is 45° relative to the optical axis of light incident on first optical surface  121 . The shape of third optical surface  122  is not particularly limited. In the present embodiment, the shape of third optical surface  122  is a flat surface. The light incident on first optical surface  121  is incident on third optical surface  122  at an incident angle larger than the critical angle. Third optical surface  122  totally reflects the incident light toward second optical surface  123 . That is, light with a predetermined light flux diameter is incident on third optical surface  122  (reflection surface), and the light with the predetermined light flux diameter is emitted toward second optical surface  123  (emission surface). 
         [0031]    Second optical surface  123  is an emission surface that emits the light totally reflected by third optical surface  122  toward the end surface of optical transmission member  116 . A plurality of second optical surfaces  123  are disposed in line in the lengthwise direction on a side surface of optical receptacle  120  so as to face respective end surfaces of optical transmission members  116 . The shape of second optical surface  123  is not particularly limited. In the present embodiment, the shape of second optical surface  123  is that of a convex lens surface protruding toward the end surface of optical transmission member  116 . This enables the light having the predetermined light flux diameter reflected by third optical surface  122  to be efficiently coupled to the end surface of optical transmission member  116 . The central axis of second optical surface  123  preferably coincides with the central axis of the end surface of optical transmission member  116 . 
         [0032]    First recesses  124  are each a recess for fixing optical transmission members  116  to optical receptacle  120  (surface on which the plurality of second optical surfaces  123  are disposed). By fitting projections of an optical transmission member attachment respectively to first recesses  124 , optical transmission members  116  are fixed to the surface of optical receptacle  120 , on which the plurality of second optical surfaces  123  are disposed. 
         [0033]    The shape and the number of first recesses  124  are not particularly limited as long as first recess  124  enables optical receptacle  120  to be fixed to substrate  112 . That is, any shape of first recess  124  is possible as long as first recess  124  has a shape complementary to the projection of the optical transmission member attachment. In the present embodiment, the shape of first recess  124  is a cylindrical shape. In addition, any number of first recesses  124  is possible as long as first recess  124  enables optical transmission member  116  to be fixed to optical receptacle  120 ; typically a plurality of first recesses  124  are formed. In the present embodiment, two first recesses  124  are disposed on the surface on which the plurality of second optical surfaces  123  are disposed, such that all second optical surfaces  123  are interposed therebetween in the lengthwise direction. The plurality of first recesses  124  are formed at positions symmetrical with respect to a plane as a symmetry plane which is parallel to the optical axis of light passing through second optical surface  123  and halves third optical surface  122  in a vertical direction. Further, the diameter and the depth of the opening of first recess  124  are not particularly limited either as long as the opening of first recess  124  has a shape complementary to the projection of substrate  112 . 
         [0034]    Second recesses  125  are each a recess for suppressing the deformation of optical receptacle  120  caused by first recess  124  during releasing in the case of producing optical receptacle  120  by injection molding. Second recess  125  opens to a side surface opposite to the surface on which first recesses  124  are disposed. The shape of second recess  125  is not particularly limited as long as stress that occurs in releasing first recess  124  can be offset. In the present embodiment, the shape of second recess  125  is a cylindrical shape. Further, the diameter and the depth of the opening of second recess  125  are not particularly limited either; the diameter and the depth thereof may be set depending on the stress that occurs in releasing first recess  124 . 
         [0035]    The plurality of first recesses  124  and the plurality of second recesses  125  are disposed opposite to each other. The central axes of plurality of first recesses  124  and the central axes of the plurality of second recesses  125  respectively coincide with each other. When the central axes of first recesses  124  and second recesses  125  fail to coincide with each other, it is not possible to offset the stress that occurs in releasing first recesses  124 . 
         [0036]    (Measurement of Distortion of Third Optical Surface) 
         [0037]    The shape of third optical surface  122  after releasing when producing optical receptacle  120  according to Embodiment 1 by injection molding was measured using an interferometer or a three-dimensional measuring instrument. In addition, for comparison, also with regard to optical receptacle  120 ′ which does not include second recesses  125 , the shape of third optical surface  122  after releasing was measured. 
         [0038]      FIGS. 4A to 4E  illustrate a configuration of optical receptacle  120 ′ according to a comparative example.  FIGS. 4A, 4B, 4C, 4D, and 4E  are, respectively, a plan view, a bottom view, a front view, a rear view, and a right side view of optical receptacle  120 ′ of the comparative example.  FIGS. 5A, 5B, 6A, and 6B  are explanatory diagrams of distortion of third optical surfaces  122  of optical receptacles  120  and  120 ′ produced by injection molding.  FIG. 5A  illustrates force applied to optical receptacle  120 ′ of the comparative example at the time of injection molding, and  FIG. 5B  is a graph showing the shape of third optical surface  122  of the comparative example after injection molding.  FIG. 6A  illustrates force applied to optical receptacle  120  according to Embodiment 1 at the time of injection molding, and  FIG. 6B  is a graph showing the shape of third optical surface  122  according to Embodiment 1 after injection molding. In  FIGS. 5B and 6B , the abscissa indicates distance d from the center of third optical surface  122 . The ordinate indicates deformation amount h of third optical surface  122  in the normal direction. 
         [0039]    First, the case of producing conventional optical receptacle  120 ′ by injection molding will be described. As illustrated in  FIG. 5A , conventional optical receptacle  120 ′ has recesses formed on a side surface, and thus requires at least a mold that molds a side surface on which recesses are formed in the injection molding. In the case where such a mold is used to perform injection molding followed by releasing, optical receptacle  120 ′ is pulled toward the mold side (downward in  FIG. 5 ) at the positions of the recesses by friction that occurs at inner surfaces of the recesses and mold portions corresponding to the recesses (see fine dotted lines in  FIG. 5A ). At that time, stress is applied to optical receptacle  120 ′ such that optical receptacle  120 ′ is curved as a whole (see fine solid lines in  FIG. 5A ). As a result, force is applied to cause third optical surface  122  to be curved as a whole, and thus third optical surface  122  is undesirably distorted (see thick solid lines in  FIG. 5A ). 
         [0040]    On the other hand, as illustrated in  FIG. 6A , optical receptacle  120  according to Embodiment 1 has first recesses  124  formed on one side surface and second recesses  125  formed on a side surface opposite to the one side surface, and thus requires a mold that molds both side surfaces opposite to each other in the injection molding. In the case where such a mold is used to perform injection molding followed by releasing, optical receptacle  120  is pulled in directions opposite to each other by friction that occurs at the inner surfaces of first recesses  124  and mold portions corresponding to first recesses  124  and by friction that occurs at the inner surfaces of second recesses  125  and mold portions corresponding to second recesses  125 . At that time, stress caused by friction that occurs at the inner surfaces of first recesses  124  and the mold portions corresponding to first recesses  124  is offset by stress caused by friction that occurs at the inner surfaces of second recesses  125  and the mold portions corresponding to second recesses  125 . Accordingly, no large force is applied to optical receptacle  120 . Therefore, as illustrated in  FIG. 6B , in optical receptacle  120 , distortion in the height direction of third optical surface  122  was suppressed. 
         [0041]    (Effects) 
         [0042]    As described above, optical receptacle  120  according to Embodiment 1 includes first recesses  124  and second recesses  125  which are disposed opposite to each other such that the central axes thereof coincide with each other, and thus can suppress the occurrence of deformation (distortion) during releasing even when optical receptacle  120  is produced by injection molding. 
       Embodiment 2 
       [0043]    An optical module according to Embodiment 2 differs from optical module  100  according to Embodiment 1 in the shape of optical receptacle  220 . Thus, the components same as those of optical module  100  according to Embodiment 1 are given the same symbols as those of optical module  100  according to Embodiment 1 and the description thereof is omitted, and different components of the optical module are mainly described. Optical receptacle  220  according to Embodiment 2 differs from optical receptacle  120  according to Embodiment 1 in that optical receptacle  220  has a plurality of recesses  221  instead of the plurality of first recesses  124  and the plurality of second recesses  125 . 
         [0044]    (Configuration of Optical Receptacle] 
         [0045]      FIGS. 7A to 7E  illustrate a configuration of optical receptacle  220  according to Embodiment 2 of the present invention.  FIGS. 7A, 7B, 7C, 7D, and 7E  are, respectively, a plan view, a bottom view, a front view, a rear view, and a right side view of optical receptacle  220  according to Embodiment 2. 
         [0046]    As illustrated in  FIGS. 7A to 7E , optical receptacle  220  according to Embodiment 2 includes a plurality of first optical surfaces  121 , third optical surface  122 , a plurality of second optical surfaces  123 , and a plurality of recesses  221 . 
         [0047]    Recesses  221  are each a portion for fixing optical transmission members  116  to optical receptacle  220  (surface on which the plurality of second optical surfaces  123  are disposed). The present embodiment is intended to suppress the deformation of the optical receptacle during releasing at the time of injection molding, by devising the shape of recess  221 . That is, recess  221  has functions of both first recess  124  and second recess  125  according to Embodiment 1. Recess  221  is formed on a side surface of optical receptacle  220 , on which the plurality of second optical surfaces  123  are disposed. Further, the number of recesses  221  is set in a manner corresponding to the number of projections of the optical transmission member attachment. In the present embodiment, two recesses  221  are disposed such that all second optical surfaces  123  are interposed therebetween. Recess  221  includes recess body  222  and tapered part  223 . 
         [0048]    The shape of recess body  222  is not particularly limited as long as recess body  222  enables optical transmission members  116  to be positioned to a surface on which the plurality of second optical surfaces  123  are disposed. In the present embodiment, the shape of recess body  222  is a cylindrical shape. The length (depth) of recess body  222  in the axial direction is preferably 0.3 mm or more from the viewpoint of positioning the projection of the optical transmission member attachment. When the length of recess body  222  in the axial direction is less than 0.3 mm, there is a risk that optical transmission members  116  cannot be properly fixed to the surface on which the plurality of second optical surfaces  123  are disposed. 
         [0049]    Tapered part  223  is a truncated cone-shaped portion for suppressing deformation of optical receptacle  220  by alleviating friction that occurs between recess  221  and a corresponding mold portion during releasing. The bottom surface of recess body  222  and the bottom surface of tapered part  223  have the same shape, and the inner peripheral surface of tapered part  223  (tapered surface) is continuous with the inner peripheral surface of recess body  222 . While the angle of the inner peripheral surface of tapered part  223  (tapered surface) relative to the central axis of recess  221  is not particularly limited, the angle thereof is about 3°, for example. It is preferable that the central axis of recess body  222  and the central axis of tapered part  223  coincide with each other. 
         [0050]    (Measurement of Distortion of Third Optical Surface) 
         [0051]      FIGS. 8A and 8B  are explanatory diagrams of distortion of third optical surface  122  of optical receptacle  220  produced by injection molding.  FIG. 8A  illustrates stress applied to optical receptacle  220  of Embodiment 2 during releasing, and  FIG. 8B  is a graph showing the shape of third optical surface  122  after releasing. In the graph of  FIG. 8B , the abscissa indicates distance d from the center of third optical surface  122 . The ordinate indicates deformation amount h of third optical surface  122  in the normal direction. 
         [0052]    As illustrated in  FIG. 8A , optical receptacle  220  according to Embodiment 2 has recesses  221  formed on a side surface, and thus requires a mold that molds a side surface side on which recesses  221  are formed, in the injection molding. In the case where such a mold is used to perform injection molding followed by releasing, optical receptacle  220  is pulled toward the mold side (downward in  FIG. 8A ) at the positions of recesses  221  by friction that occurs at the inner surfaces of recesses  221  and the mold portions corresponding to recesses  221  (see fine dotted lines in  FIG. 8A ). At that time, tapered part  223  is formed at the bottom of recess  221 , and thus friction is alleviated in optical receptacle  220  compared to optical receptacle  120 ′ of the comparative example illustrated in  FIGS. 5A and 5B . Therefore, as illustrated in  FIG. 8B , in optical receptacle  220 , distortion of third optical surface  122  in the height direction was suppressed. 
         [0053]    (Effects) As described above, optical receptacle  220  according to Embodiment 2 can suppress the occurrence of deformation (distortion) during releasing even when optical receptacle  220  is produced by injection molding, since recesses  221  each include tapered part  223  formed at the bottom thereof. 
         [0054]    Note that, while a case where first optical surfaces  121  and second optical surfaces  123  are a convex lens surface is shown in optical receptacles  120  and  220  according to the respective embodiments described above, first optical surfaces  121  and second optical surfaces  123  may be a flat surface. Specifically, only first optical surface  121  may be a flat surface, or only second optical surface  123  may be a flat surface. When first optical surface  121  is formed in a flat surface, third optical surface  122  is formed to function as a concave mirror, for example. When light immediately before reaching second optical surface  123  is effectively converged by first optical surface  121 , third optical surface  122 , or the like, second optical surface  123  may be formed in a flat surface. 
         [0055]    Further, optical receptacles  120  and  220  according to the respective embodiments described above may also be used for a receiving optical module. In this case, the receiving optical module includes a plurality of light receiving elements for receiving light instead of the plurality of light emitting elements  114 . The plurality of light receiving elements are disposed on the same positions as the respective corresponding light emitting elements. The receiving optical module has second optical surfaces  123  as incidence surfaces, and first optical surfaces  121  as emission surfaces. Light emitted from the end surface of optical transmission member  116  enters the optical receptacle from second optical surface  123 . The light having entered the optical receptacle is reflected by third optical surface  122  to be emitted from first optical surface  121  toward the light receiving element. In the case of an optical module not having a reflection surface, light having entered the optical receptacle is emitted from first optical surface  121  toward the light receiving element. 
         [0056]    This application is entitled to and claims the benefit of Japanese Patent Application No. 2013-267214, filed on Dec. 25, 2013, the disclosure of which including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
       INDUSTRIAL APPLICABILITY 
       [0057]    The optical receptacle and optical module according to the present invention are advantageous for optical communications using optical transmission members. 
       REFERENCE SIGN LIST 
       [0000]    
       
           10  Optical receptacle 
           12  Incidence surface 
           14  Reflection surface 
           16  Emission surface 
           18  Guide hole 
           100  Optical module 
           110  Photoelectric conversion device 
           112  Substrate 
           114  Light emitting element 
           116  Optical transmission member 
           120 ,  120 ′,  220  Optical receptacle 
           121  First optical surface (Incidence surface) 
           122  Third optical surface (Reflection surface) 
           123  Second optical surface (Emission surface) 
           124  First recess 
           125  Second recess 
           221  Recess 
           222  Recess body 
           223  Tapered part