Abstract:
An optical waveguide or first optical fiber whose one end optically connects with a light exit plane and/or light incidence plane of an optical element and whose other end optically connects with an second optical fiber and a connector for mechanically connecting the optical waveguide or the first optical fiber and the second optical fiber are included. The optical waveguide or first optical fiber is bent in order to change the traveling direction of light so that the light incoming from one end is emitted from the other end substantially in parallel with a board and the light incoming substantially in parallel with the board to the optical waveguide or first optical fiber from the other end is emitted from one end toward the optical element.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an optical connector and an optical module, particularly to a technique for realizing optical coupling between an optical element mounted on a board and an optical fiber at low cost. 
   2. Description of the Related Art 
   As the bit rate increases in an information device such as a computer, in-board optical coupling for connecting LSIs such as CPUs or memories by an optical fiber or optical waveguide is considered promising. In in-board optical coupling, an LSI having an optical-signal input/output function is used. Optical signals inputted to or outputted from the LSI are transmitted through an optical fiber or optical waveguide. 
   When LSIs mounted on a board are optically coupled to each other by an optical fiber or optical waveguide, handling of the extra length of the optical fiber or optical waveguide may be complicated. Therefore, it is preferable that an LSI and optical fiber or optical waveguide be detachable from each other. An optical module to which an optical fiber is removably attached is described in General Assembly Lecture Collected Papers C-3-123-C-3-127 (hereafter referred to as “prior document”) of The Institute of Electronics 2003. 
     FIG. 1  shows a sectional view of an optical module described in the prior document As shown in  FIG. 1 , vertical cavity surface emitting laser (VCSEL)  182 , laser diode driver (LDD)  183  for driving VCSEL  182 , and AC-connecting capacitor  186  are mounted on transparent resin board  181 . VCSEL  182  and LDD  183  are covered with metallic shielding frame  188 . Light (optical signal) emitted from VCSEL  182  enters reflection mirror  190  that is tilted to 45° through condenser lens (lens array)  184 . The light entering reflection mirror  190  is reflected by reflection mirror  190  and enters optical fiber  192 . Condenser lens  184  is provided in optical I/O connector holder  185 . Reflection mirror  190  and optical fiber  192  are provided in optical I/O connector  191 . By changing the direction of the light that is emitted from VCSEL  182  to the direction parallel with board  181  by reflection mirror  190 , it is possible to lower the height of the space above board  181 . LDD  183  is electrically connected with a multilayer board (BGA board  189 ) through a resin board (interposer  187 ) having a via-plug. A solder bump is used for making electrical connection between interposer  187  and BGA board  189 . 
   Optical I/O connector  191  having reflection mirror  190  and optical fiber  192  is removably attached to optical connector holder  185 . The optical axis between optical I/O connector  191  and optical connector holder  185  is adjusted by means of a not-illustrated guide pin and a through-hole formed on condenser lens  184 . In this case, because the effective optical-path length from the exit plane of VCSEL  182  up to the incident plane of optical fiber  192  is large, it is difficult to obtain sufficient coupling efficiency without using a lens. In the optical module described in the prior document, sufficient coupling efficiency is secured by using condenser lens  184 . Moreover, in the optical module described in the prior document, condenser lens  184  is provided on transparent resin board  181  on which VCSEL  182  is mounted. Therefore, even if the optical axis of optical fiber  192  is displaced due to insertion or removal of optical I/O connector  191 , optical coupling and connection separation are performed by using a large optical beam diameter. As a result, stable optical coupling efficiency can be obtained. 
   However, because a reflection mirror is indispensable for the optical module described in the prior document, fabrication costs increase. Moreover, fabrication costs increase because angle adjustment of the reflection mirror is necessary. Furthermore, it is necessary to use a lens in order to obtain stable optical coupling efficiency. However, the lens is expensive and lens mounting work is costly. 
   To reduce the cost of the optical module, it is important to reduce the number of parts and the assembly man-hours. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to realize highly efficient optical coupling between an optical element and an optical fiber or optical waveguide at a low cost. 
   A first optical connector of the present invention is an optical connector for removably connecting a board on which an optical element is mounted and a second optical fiber. This optical connector has an optical waveguide or first optical fiber, support and connector. 
   One end of the above optical waveguide or first optical fiber is optically connected with the light exit plane and/or light incidence plane of an optical element and the other end is optically connected with the second optical fiber. The above support supports the optical waveguide or first optical fiber. The above connector mechanically connects the support and the second optical fiber. 
   The support supports the optical waveguide or first optical fiber so that the traveling direction of the light entering the optical waveguide or first optical fiber is changed to a predetermined direction. Specifically, the traveling direction of the light incoming from one end of the optical waveguide or first optical fiber is changed so the light is emitted in a direction substantially parallel with board surface from the other end of the optical waveguide or first optical fiber. Moreover, the traveling direction of the incoming light substantially parallel with the board surface from the other end of the optical waveguide or first optical fiber is changed so that the light is emitted to an optical element from one end of the optical waveguide or first optical fiber. 
   A first optical module of the present invention has a board on which an optical element is mounted and has the first optical connector of the present invention. 
   In the above first optical connector, the optical element is optically connected with the second optical fiber by the optical waveguide or first optical fiber. Therefore, optical components such as a lens and reflection mirror are unnecessary. Moreover, light enters and exits substantially parallel to the board on which an optical element is mounted so as to optically connect the element to the second optical fiber. Therefore, the board does not have bulk. Furthermore, because a connector for connecting a support with the second optical fiber is used, it is possible to easily perform optical rewiring with an optical fiber. 
   A coaxial via-plug which passes through a support may be formed to direct an electrical signal from a board to a circuit board. The coaxial via-plug formed on the support may help reduce the number of electrical wiring substrates such as resin substrates respectively provided with a coaxial via-plug. Moreover, because the coaxial via-plug penetrates the support and is able to connect with an electrical socket provided on the above circuit board, a board on which an optical element is mounted can be separated from a circuit board and a component can be easily replaced upon failure. As a result, it is possible to reduce the cost of a board or apparatus on which an optical module is mounted. 
   A second optical connector of the present invention is an optical connector for removably connecting a board on which an optical element is mounted with a second optical fiber. The optical connector has an optical waveguide or first optical fiber that is provided in the above described board and connector for mechanically connecting the above mentioned board with the second optical fiber. 
   One end of the above optical waveguide or first optical fiber optically connects with the light exit plane and/or light incidence plane of the optical element, and the other end of the above optical waveguide or first optical fiber optically connects with the above second optical fiber. 
   The above board supports the optical waveguide or first optical fiber so that the traveling direction of light entering the optical waveguide or first optical fiber is changed in a predetermined direction. Specifically, the traveling direction of the light incoming from one end of the optical waveguide or first optical fiber is changed so that light is emitted in a direction substantially parallel with the board surface from the other end of the optical waveguide or first optical fiber. Moreover, the traveling direction of incoming light substantially parallel with the board surface from the other end of the optical waveguide or first optical fiber is changed so that light is emitted toward the optical element from the one end of the optical waveguide or first optical fiber. 
   In the above second optical connector, an optical element is optically connected with a second optical fiber by the optical waveguide or first optical fiber that is provided in a substrate on which an optical element is mounted. Therefore, an optical component such as a lens or reflection mirror is unnecessary. Moreover, because the optical element is mounted on the board in which the optical waveguide or first optical fiber is built, it is possible to mount the optical element while confirming the position of light entrance portion of the optical waveguide or first optical fiber. Therefore, it is possible to easily and accurately assemble the optical connector. 
   On a substrate on which an optical element is mounted, it is possible to form a plurality of coaxial via-plugs that are electrically connected with an electrical element for driving the above optical element and that penetrate the face of the substrate on which the above optical element is mounted and the other face of the substrate. By forming the coaxial via-plug on the board on which the optical element is mounted, it is possible to reduce the number of electrical wiring substrates such as resin substrates respectively provided with a coaxial via-plug. 
   Because the above coaxial via-plug penetrates the board on which the optical element is mounted and is able to connect with an electrical socket provided on the circuit board, the board on which the optical element is mounted can be separated from the circuit board, and components when a problem occurs can be easily replaced. As a result, it is possible to reduce the cost of a board or apparatus on which an optical module is mounted. 
   The above and other objects, features and advantage of the present invention will become apparent from the following description with reference to the accompanying drawings which illustrate examples of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of the optical module of a conventional example; 
       FIG. 2A  is a side view of the optical module of the first embodiment and  FIG. 2B  is a top view of the first embodiment; 
       FIG. 3  is a decomposed view of the optical module of the first embodiment; 
       FIG. 4  is a decomposed perspective view of the optical module of the first embodiment; 
       FIG. 5A  is a side view of the optical module of second embodiment and  FIG. 5B  is a top view of the optical module of the second embodiment; 
       FIG. 6  is a decomposed side view of the optical module of the second embodiment; 
       FIG. 7  is a top view of the transparent resin board shown in  FIG. 6 ; 
       FIG. 8  is a decomposed side view of the optical module of the second embodiment; and 
       FIG. 9  is a decomposed side view of the optical module of the third embodiment. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2006-098483 filed on Mar. 31, 2006, the content of which is incorporated be reference. 
   First Embodiment 
     FIG. 2A  is a side view of optical module  10  of this embodiment and  FIG. 2B  is a top view.  FIG. 3  is a decomposited side view of optical module  10  of this embodiment.  FIG. 4  is a decomposited perspective view of optical module  10  of this embodiment. 
   As shown in  FIGS. 2A and 2B ,  3 , and  4 , optical module  10  has optical element  11 , electrical element  12 , transparent resin board  13 , circuit board  26 , interposer  15 , transparent-resin-board holding table  16 , and metallic shielding frame  17 . 
   Optical element  11  of this embodiment is a light emitting element. More specifically, optical element  11  is an array-shaped surface-emitting laser. Electrical element  12  of this embodiment is a laser diode driver. Optical element  11  and electrical element  12  are flip-chip-mounted on transparent resin board  13 . Interposer  15  is a resin board provided with a coaxial via-plug for introducing an electrical signal to circuit board  26  from transparent resin board  13 . Transparent-resin-board holding table  16  helps to improve the accuracy for aligning optical connector  30  and helps to enhance strength and heat dissipation of optical module  10 . Metallic shielding frame  17  serves to prevent electrical crosstalk, to strengthen reinforcement of optical module  10 , and to dissipate heat. 
   Optical element  11  can be replaced with a light-receiving element. Both light-emitting and light-receiving elements may be mounted as optical element  11 . As an example of a light-receiving element, an array-shaped photodiode is used. When the photodiode is mounted, a photodiode receiver is mounted as electrical element  12 . 
   Optical module  10  is provided with optical connector  30  constituted of optical waveguide  19  for introducing an optical signal output from optical element (light-emitting element)  11  to optical fiber  18 , optical waveguide support  20  for holding optical waveguide  19  and holding plate  21 . When optical element  11  is a light-receiving element, optical waveguide  19  introduces an optical signal that is outputted from optical fiber  18  to optical element (light-receiving element)  11 . Thickness L of optical connector  30  is preferably in the order of 5 to 15 mm. Thickness L of optical connector  30  of this embodiment is approximately 10 mm. 
   As shown in  FIG. 4 , support  20  has optical waveguide guide  20   c . Optical waveguide guide  20   c  has an opening through which an end of optical waveguide  19  contacts with transparent resin board  13 . Holding plate  21  serves as support of optical waveguide  19  and MT connector  28 . 
   Positioning hole  22   a  is formed on transparent resin board  13  of optical module  10 . Optical connector  30  has pin  22   b  which can be fitted to positioning hole  22   a . Optical connector  30  is directly connected to transparent resin board  13 , and an optical signal output from optical element (light-emitting element)  11  is introduced to optical fiber  18 . When optical element  11  is a light-receiving element or the light-receiving element is included in optical element  11 , an optical signal output from optical fiber  18  is introduced to the optical element. Transparent-resin-board holding plate  16  encloses three sides of optical connector  30  and positions optical connector  30  from the outside. 
   It is also possible to set positioning hole  22   a  to optical connector  30  and to set pin  22   b  to transparent resin board  13 . Moreover, it is possible to set positioning hole  22   a  or pin  22   b  to transparent board holding plate  16 . 
   Because optical waveguide  19  and transparent resin board  13  directly contact each other, an optical component such as a lens is not necessary. 
   Therefore, the number of components constituting an optical module and optical connector is reduced and it is possible to fabricate an optical module at a low cost. 
   Transparent resin board  13  has permeability to the wavelength of the light inputted to or outputted from optical element  11 . Transparent resin board  13  includes electrical wiring  23  for transmitting an electrical signal to control a laser diode driver and photodiode receiver, and includes electrical element  24  such as a capacitor, dielectric layer, and polyimide layer (protective layer). It is unnecessary that the entire of transparent resin board  13  be transparent. It is sufficient that board  13  be optically transparent for an optical signal inputted to or outputted from the optical element. Therefore, it is sufficient that at least the region of transparent resin board  13  facing optical element  11  be transparent. The same is true for other embodiments. 
   The electrical signal is transmitted from electrical wiring  23  of transparent resin board  13  to circuit board  26  through coaxial via-plug  14  of interposer  15  and bump  25 . 
   Because transparent resin board  13  is directly connected with optical waveguide  19 , it is preferable that the thickness of board  13  be tens of microns. It is also preferable that the distance between transparent resin board  13  and optical element  11  that is flip-chip-mounted on board  13  be tens of microns. 
   It is possible to adjust the distance between transparent resin board  13  and optical element  11  by changing the diameter of metallic (Au) bump  27 . When considering optical loss, it is preferable that the thickness of transparent resin board  13  be minimized. 
   It is preferable to form reflection preventive film  32  on a face of transparent resin board  13  to which optical waveguide  19  is directly connected, as shown in  FIG. 3 . Or, it is preferable to fill the gap between transparent resin board  13  and optical waveguide  19  with solvent (matching oil)  33  or adhesive  33  having substantially the same refractive index as transparent resin board  13  and optical waveguide  19 . 
   Moreover, to restrain the light emission angle from board  13  by decreasing the gap (optical path length) between optical element  11  and transparent resin board  13 , it is preferable to fill the gap between board  13  and optical element  11  with under-fill agent  34  ( FIG. 2A ) having a refractive index higher than that of air. 
   By using under-fill agent  34 , which is transparent to the wavelength of light inputted/outputted to and from optical element  11  and has a refractive index substantially equal to that of transparent resin board  13 , it is possible to restrain the reflection between transparent resin board  13  and optical element  11 . 
   As shown in  FIG. 3 , support  20  can be connected with optical fiber  18 . Support  20  has a positioning structure compatible with a standard connector mounted on optical fiber  18 . Support  20  of this embodiment has positioning hole  29   a  into which pin  29  of MT (Mechanically Transferable) connector  28  can be inserted and has MT connector support portion  31 . Pin  29  may also be provided to support  20  and positioning hole  29   a  may be provided to MT connector  28 . In  FIG. 4 , MT connector support portion  31  is omitted. A connector is not restricted to the MT connector. Connectors other than the MT connector can also be used. 
   Support  20  directly contacts transparent resin board  13 . It is preferable to fix support  20  and transparent resin board  13  by using the above adhesive  33  or the like. 
   As shown in  FIGS. 3 and 4 , optical waveguide guide  20   c  is provided to support  20  for supporting optical waveguide  19  in order to accurately attach optical waveguide  19 . The optical waveguide  19  is bent along optical waveguide guide  20   c.    
   By using optical waveguide  19  formed of a soft material such as polymer, bend loss is kept within 1 dB even if optical waveguide  19  is bent in the range of a curvature radius between 2 mm and 10 mm. 
   By ensuring that optical waveguide guide  20   c  and positioning hole  22   a  are accurate, optical connector  30  and optical element  11  can be accurately positioned and it is possible to easily optically connect optical waveguide  19  with optical element  11 . 
   As described above, by providing optical element  11  and electrical element  12  to drive optical element  11  to one face of transparent resin board  13 , and by positioning one face of bent optical waveguide (curved waveguide)  19  so as to contact the other face of transparent resin board  13 , it is possible to omit a lens and reflection mirror. 
   For example, the thickness of transparent resin board  13  is set to 20 μm. Optical element  11  having a radiation angle of 30° is flip-chip-mounted on the component side of transparent resin board  13 . The gap between optical element  11  and the component sides of transparent resin board  13  is set to 10 μm. Under the above conditions, the diameter of the light flux after passes through the transparent resin board  13  becomes approximately 20 μm. Therefore, by setting the diameter of optical waveguide  19  to 50 μm, it is possible to realize optical coupling of the light output from optical element  11  to optical waveguide  19  with sufficient tolerance. Therefore, a lens for optically coupling the light output from optical element  11  with optical waveguide  19  is unnecessary. 
   The reflection mirror is replaced by curved waveguide  19 . Curved waveguide  19  can be easily formed by bending a rectilinear waveguide made of a soft material such as inexpensive polymer waveguide or film waveguide at a curvature radius of 2 to 10 mm. Moreover, it is possible to accommodate an optical module on which many optical elements are mounted by bending a rectilinear waveguide having an array structure similarly to the above described. Therefore, it is unnecessary to prepare a curved waveguide having a particular structure. It is possible to form a curved waveguide by using a commercial polymer waveguide, a fiber sheet, or a ribbon fiber. 
   To accurately fix optical waveguide  19  to support  20 , it is preferable that a recess for alignment be formed on support  20 , as shown in  FIG. 4 . It is preferable that the end of optical waveguide  19  that contacts transparent resin board  13  be mirror-polished or that a reflection preventive film be formed on the end. 
   As described above, optical module  10  of this embodiment realizes high-efficiency optical coupling without using lens  184  or reflection mirror  190  shown in  FIG. 1 . Therefore, the number of components is reduced and the cost for mounting the lens and reflection mirror is reduced. 
   Because a standard connector such as the MT connector mounted on optical fiber  18  can be removably attached to optical connector  30 , it is possible to easily change the destination of an optical signal. 
   Second Embodiment 
   In optical module  10  of the first embodiment, optical connector  30  in which optical waveguide  19  is built is set on transparent resin board  13 . In the optical module of this embodiment, a recess is formed on a transparent resin board and an optical waveguide is provided in the recess. 
   Transparent resin board  13  of the first embodiment is directly connected to optical waveguide  19 . Therefore, to reduce optical loss, it is preferable to set the thickness of transparent resin board  13  to tens of microns, Moreover, it is preferable that the distance between transparent resin board  13  and optical element  11  be tens of microns. 
   However, it is sufficient that only the region on which an optical element is mounted be thin. That is, it is sufficient that a region to or from which an optical signal is input or output have a thickness that is small. It is better that the thickness of the region of transparent resin board  13  other than the region to or from which an optical signal is input or output is large because this is advantageous in strength, radiation characteristic, and working accuracy. Moreover, by setting the thickness of transparent resin board  13  to approximately 10 mm, it is possible to omit support  20  and to use transparent resin board  13  for holding an optical waveguide  19 . Therefore, the number of components is further reduced and cost can be reduced. 
     FIG. 5A  shows a side view of optical module  40  of this embodiment.  FIG. 5B  shows a top view of optical module  40 .  FIG. 6  is a decomposed side view of optical module  40 .  FIG. 7  is a top view of transparent resin board  41 .  FIG. 8  is a decomposed perspective view of optical module  40 . The same material as the material shown in  FIGS. 2 to 4  is provided with the same symbol. 
   An optical connector is constituted of transparent resin board  41 , MT connector  28 , optical waveguide  19 , and transparent resin board holding plate  42 . Optical module  40  is constituted of the optical connector on which optical element  11  and electrical element  12  are mounted and interposer  15  which is connected to the optical connector. 
   Optical module  40  of this embodiment has optical element  11 , electrical element  12 , transparent resin board  41 , circuit board  26 , interposer  15 , transparent resin board holding plate  42 , and metallic shielding frame  17 . 
   Optical element  11  of this embodiment is a light-emitting element. More specifically, optical element  11  is an array-shaped face-emitting laser. Electrical element  12  of this embodiment is a laser diode driver. Optical element  11  and electrical element  12  are flip-chip-mounted on transparent resin board  41 . Interposer  15  is a resin board provided with a coaxial via-plug for introducing an electrical signal from transparent resin board  41  to circuit board  26 . Transparent resin board holding plate  42  serves to hold optical waveguide  19 , to strengthen reinforcement of optical module  40 , and to dissipate heat. Metallic shielding frame  17  serves to prevent electrical crosstalk, to strengthen reinforcement of optical module  40 , and to dissipate heat. 
   Optical element  11  can be changed to a light-receiving element. Moreover, it is possible to mount both light-emitting element and light-receiving element as optical element  11 . The light-receiving element is, for example, an array-shaped photodiode. When the photodiode is mounted, a photodiode receiver is mounted as electrical element  12 . 
   As shown in  FIGS. 6 and 7 , thickness L 1  of transparent resin board  41  is approximately 10 mm. Transparent resin board  41  has a structure for holding optical waveguide  19 . The thickness of transparent resin board  41  in the portion between the ends of optical element  11  and optical waveguide  19  is reduced up to tens of microns in order to introduce an optical signal to optical waveguide  19  from optical element  11 . Optical coupling between optical waveguide  19  and optical fiber  18  is performed by connecting MT connectors  28  by pin  29 . 
   Optical waveguide  19  is fixed along recess  44  of transparent resin board  41 . Specifically, the front end of optical waveguide  19  is fixed to recess  44  by a fixing agent (adhesive). Thereafter, optical waveguide  19  is bent along recess  44  to fix the bent optical waveguide  19  to recess  44 . 
   MT connector  28  or the like is attached to an end to be connected with optical fiber  18  of optical waveguide  19 . 
   As described above, by setting optical waveguide  19  in transparent resin board  41 , it is not only a lens and reflection mirror but also support  20  of the first embodiment becomes unnecessary and the number of components is reduced. Therefore, it is possible to fabricate an optical module at lower cost. 
   Moreover, in this embodiment, it is possible to mount an optical element after mounting (bonding) optical waveguide  19  on transparent resin board  41 . Therefore, because optical element  11  can be mounted after confirming the position of optical input portion of optical waveguide  19 , it is possible to easily and securely improve optical coupling efficiency. 
   Third Embodiment 
   In the second embodiment, transparent resin board holding plate  42 , interposer  15 , and circuit board  26  face both sides of transparent resin board  41 . The electrical connection of circuit board  26  is secured by a coaxial via-plug provided to interposer  15 . 
     FIG. 9  shows a side view of optical module  50  of this embodiment. As shown in  FIG. 9 , in optical module  50  of the embodiment, coaxial vie-plug  53  is provided to transparent resin board  51 . Moreover, electrical socket  52  is provided on the same side as the side at which transparent resin board holding plate  54  is provided. Furthermore, the electrical connection of electrical socket  52  is secured by coaxial via-plug  53  provided to transparent resin board  51 . 
   The same material as the material described above is provided with the same symbol in  FIG. 9 . The structure of transparent resin board  51  is the same as that of transparent resin board  41  shown in  FIGS. 5 to 7  except for coaxial via-plug  53 . 
   Optical element  11  of this embodiment is a light-emitting element. More specifically, element  11  is an array-shaped surface-emitting laser. Electrical element  12  of this embodiment is a laser diode driver. Optical element  11  and electrical element  12  are flip-chip-mounted on transparent resin board  51 . Optical waveguide  19  is provided in transparent resin board  51 . Moreover, coaxial via-plug  53  for transmitting an electrical signal to electrical socket  52  is formed on transparent resin board  51 . It is possible to change electrical socket  52  to an adapter and a circuit board to be connected with coaxial via-plug  53 . 
   The illustrated transparent resin board holding plate  54  serves to hold optical waveguide  19  and coaxial via-plug  54 , to strengthen reinforcement of optical module  10  and to dissipate heat. Metallic shielding frame  17  serves to prevent electrical crosstalk, to strengthen reinforcement of optical module  50 , and to dissipate heat. 
   Optical element  11  can be changed to a light-receiving element. Moreover, it is possible to mount both light-emitting element and light-receiving element as optical element  11 . The light-receiving element is, for example, an array-shaped photodiode. When the photodiode is mounted, a photodiode receiver is mounted as electrical element  12 . 
   Optical waveguide  19  in transparent resin board  51  is a curved waveguide. Optical waveguide  19  is directly mounted on transparent resin board  51  and is able to efficiently fetch an optical signal output from optical element  11  in the direction parallel with electrical socket  52 . 
   By forming coaxial via-plug  53  on transparent resin board  51 , it is possible to omit interposers  15  of the first and second embodiments. Therefore, it is possible to omit not only optical components such as a lens and reflection mirror but also an electrical wiring board such as an interposer. 
   Moreover, the stiffness of optical module  50  is reinforced because metallic shielding frame  17 , thick transparent resin board  51 , and transparent resin board holding plate  54  are present. Therefore, optical module  50  of this embodiment can sufficiently withstand stress produced when attaching and removing optical module  50  to or from electrical socket  52 . 
   Moreover, by mounting electrical socket (adapter)  52  to a circuit board (not-illustrated), it is possible to change optical module  50  by only setting or removing coaxial via-plug  53 . 
   Because coaxial via-plug  53  penetrates transparent resin board  51  and is able to connect with an electrical socket on the circuit board, transparent resin board  53  and a circuit board can be easily separated from each other. Therefore, components can be easily replaced when a problem occurs and it is possible to reduce the cost of a board or apparatus on which an optical module is mounted. 
   Optical module  50  of this embodiment having transparent resin board  51  on which optical waveguide  19  and coaxial via-plug  53  are mounted can be fabricated at a lower cost than that of optical modules  10  and  40  of the above embodiment. Therefore, an apparatus or circuit board on which optical module  50  of this embodiment is mounted is reduced in cost. 
   In optical module  50  of this embodiment, optical waveguide  19  is provided in transparent resin board  51  on which optical element  11  is mounted. However, as shown in the first embodiment, it is permissible to use a support separately from a transparent resin board and to provide a coaxial via-plug to an optical waveguide support. 
   While preferred embodiments of the present invention have been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.