JP4775284B2 - Optical transmission module - Google Patents

Description

  The present invention relates to an optical transmission module including an optical waveguide. Specifically, a highly accurate optical connector can be realized with a simple configuration by abutting the end faces of optical waveguides that expose the end face of the core that transmits optical signals, and aligning the optical axes. It is.

  Conventionally, signal transmission between printed wirings is performed by an electrical signal via a flexible substrate or an electrical signal via a connector harness. However, recently, the amount of data handled in an electric circuit has increased remarkably, and there is a tendency to increase the speed and capacity. As a result, various high frequency problems are emerging.

  Typical high frequency problems include RC signal delay, impedance mismatching, EMC, EMI, crosstalk, and the like. Conventionally, in order to solve these problems, optimization of wiring positions, development of new materials, and the like have been performed. However, the optimization of the wiring positions and the effects of new materials described above are being hampered by physical limitations, and a new wiring technology has become necessary to realize higher performance of the system in the future.

  For example, in order to realize high speed and large capacity of signal transmission / reception, an optical transmission coupling technique using optical wiring has been developed. By performing signal transmission between semiconductor chips or printed wiring boards using optical signals, there is no problem of RC delay as in electrical wiring, and transmission speed can be greatly improved. In addition, by performing signal transmission between semiconductor chips or printed wiring boards using optical signals, it is not necessary to take any countermeasures against electromagnetic waves, and relatively free wiring design is possible compared to electrical wiring.

  There are various methods for optical wiring technology between printed wiring boards. For example, optical wiring technology using a flexible optical waveguide will be briefly described with the following two examples.

  FIG. 14 is a configuration diagram showing an example of a conventional optical module by optical connector connection. In the example shown in FIG. 14, a light emitting element 702a and a driver amplifier 703a are mounted on a printed wiring board 701a on the output side, and a socket 705a to which an optical connector 704a is attached and detached is mounted. Similarly, a light receiving element 702b and a transimpedance amplifier 703b are mounted on a printed wiring board 701b on the input side, and a socket 705b to which an optical connector 704b is attached and detached is mounted.

  The optical waveguide 706 that transmits signals between the printed wiring boards 701a and 701b is formed as a connector, and has a structure that can be fitted to and detached from the sockets 705a and 705b on the printed wiring boards 701a and 701b.

  In such a configuration, the optical signal output from the light emitting element 702 a enters the optical waveguide 706. Incident light is totally reflected by the 45-degree reflecting surface at the end of the optical waveguide 706, and the optical path is bent 90 degrees to be transmitted through the core of the optical waveguide 706.

  As an advantage of this method, the printed wiring boards 701a and 701b are secondarily mounted on the main printed wiring boards 707a and 707b, thereby shortening the wiring length of the high-frequency electrical signal between the optical communication IC 708 and the optical element driver. it can. The optical waveguide is made into a connector and made into a completely independent component with respect to the printed wiring board, so that it is not affected by heat during mounting (reflow) of the electronic component. This expands the options for the optical waveguide material.

  As a problem, it is necessary to align the optical axis with high precision when connecting the optical connector, and as a structure corresponding to this, it is necessary to install a microlens 709 for collimating the light flux that absorbs the deviation. In addition, it is necessary to install a cover 710 for suppressing adhesion of dust, dust, etc. to the optical element when the connector is attached / detached. For this reason, there is concern about an increase in the number of parts, which makes it difficult to reduce the cost and size.

  FIG. 15 is a block diagram showing an example of a conventional optical module by electrical connector connection. In the example shown in FIG. 15, a light emitting element 802a, a driver amplifier 803a, and an electrical connector 804a are mounted on a printed wiring board 801a on the output side. Similarly, the light receiving element 802b, the transimpedance amplifier 803b, and the electrical connector 804b are mounted on the printed wiring board 801b on the input side.

  The optical waveguide 805 that performs signal transmission between the printed wiring boards 801a and 801b has a structure in which the optical waveguide 805 is adhered to the printed wiring boards 801a and 801b in a state where the optical waveguide 805 is accurately aligned with the optical axis of each optical element. .

  Connections between the main printed wiring boards 807a and 807b on which the IC for optical communication 806 is mounted and the printed wiring boards 801a and 801b are made by electrical connectors 808a and 808b, respectively.

  In such a configuration, the optical signal output from the light emitting element 802 a enters the optical waveguide 805. Incident light is totally reflected by the 45 ° reflection surface at the end of the optical waveguide 805, and the optical path is bent 90 degrees to be transmitted through the core of the optical waveguide 805.

  As an advantage of this method, since the connection between the main printed wiring board and the printed wiring board is performed by an electrical connector, if the optical axes of the optical element and the optical waveguide are aligned when manufacturing the optical module, the optical axis is There is no worry about shifting. Since the optical element can have a sealed structure by the optical waveguide, the influence of dust and dust can be suppressed. Furthermore, the number of parts is small, and the size and thickness can be reduced.

  As a problem, high frequency countermeasures are necessary because high frequency electrical signals flow through the electrical connector. In addition, the wiring length of the high-frequency electrical signal is increased by using an electrical connector between the optical communication IC and the optical element driver. Furthermore, since the optical waveguide is integrated with the electronic component, it is easily affected by the mounting of the optical element (at the time of reflow), and a specification that takes heat resistance into consideration is required, which increases the restrictions on material selection.

  Furthermore, as a detachable optical connector, a groove portion and a convex portion, a pin and a hole portion are formed in the optical connector and the housing, alignment is performed by fitting the groove portion and the convex portion, etc., and fixing is performed by locking the claw portion. The structure performed is employ | adopted (for example, refer patent document 1).

Japanese Patent No. 3636634

  However, in the conventional optical connector, the alignment is performed by fitting the groove portion and the convex portion, etc., so if the connector or the housing is deformed due to changes in the environment such as external force or temperature, the optical axis is easily displaced, and the external force There was a problem of being easily affected by environmental changes.

  SUMMARY An advantage of some aspects of the invention is that it provides an optical transmission module in which a high-precision optical connector is realized with a simple configuration.

  In order to solve the above-described problems, an optical transmission module of the present invention includes an optical connector having an optical waveguide formed with a joint end surface exposing an end surface of a core through which an optical signal is transmitted, and an optical waveguide of the optical connector. A socket having a mounting portion to be mounted and an optical waveguide formed with an end surface of a core through which an optical signal is transmitted and having a joint end surface formed thereon; the socket is mounted; A mounting substrate on which an optical element to be optically coupled is mounted at an end opposite to the joint end face, and a socket that is detachably attached to the socket, and the joint end faces of the optical waveguide of the optical connector and the optical waveguide of the socket A cover having a biasing means for biasing the optical connector in a direction in which the optical waveguide of the connector and the mounting portion of the socket abut, and the position of the optical axis between the optical waveguide of the optical connector and the core of the optical waveguide of the socket Characterized in that a positioning means to align.

  In the optical transmission module of the present invention, when the optical waveguide of the optical connector is mounted on the mounting portion of the socket and the cover is mounted on the socket, the position of the optical axis between the optical waveguide of the optical connector and the core of the optical waveguide of the socket is The optical connector is attached to the socket in a state where the joint end faces of the optical waveguide of the optical connector and the optical waveguide of the socket and the optical waveguide of the optical connector and the mounting portion of the socket are biased.

  In the optical transmission module according to the present invention, the mounting board is mounted on another wiring board by mounting the mounting board on which the optical element and the electronic component for driving the optical element are mounted, and the optical communication IC and A wiring structure that can shorten the wiring length between the optical elements can be realized.

  According to the optical transmission module of the present invention, a force is applied to the optical connector attached to the socket in a direction along the optical axis and in a direction perpendicular to the optical axis, so that the optical waveguide of the optical connector and the optical Since the positions of the optical axes of the cores of the waveguide are matched, the influence of external force and environmental changes can be suppressed, and a highly accurate optical connector can be realized with a simple configuration.

  As a result, signal transmission between substrates and the like can be performed by optical signals, high-frequency problems such as countermeasures against electromagnetic waves in the configuration for transmitting electrical signals can be solved, and the degree of freedom in designing the substrate can be improved.

  Hereinafter, embodiments of the optical transmission module of the present invention will be described with reference to the drawings.

<Configuration example of optical transmission module of the present embodiment>
FIG. 1 is a side sectional view showing an example of the optical transmission module of the present embodiment, FIG. 2A is a sectional view taken on line AA of the optical transmission module shown in FIG. 1, and FIG. FIG. 3 is a partially broken exploded perspective view of the optical transmission module of the present embodiment.

  4 is a perspective view of the optical waveguide array constituting the optical transmission module of the present embodiment, FIG. 5A is a view in the direction of the arrow C of the optical transmission module shown in FIG. 4, and FIG. These are the D direction arrow directional views of the optical transmission module shown in FIG.

  The optical transmission module 1A according to the present embodiment includes a socket 3 to which an optical connector 2 is attached and detached to a printed wiring board 10 that is a mounting board on which a light emitting element 10a that outputs an optical signal, for example, is mounted as an optical element. Further, a cover 4 is provided for aligning and fixing the optical connector 2 to the socket 3.

  The optical transmission module 1A includes an optical waveguide array 20 having a core 20a through which an optical signal is transmitted, in the optical connector 2, and as shown in FIGS. 4 and 5B, at the end of the optical waveguide array 20, A joining end face 21 is formed by exposing the end face of the core 20a. Further, the socket 3 is provided with an optical waveguide array 30 having a core 30a through which an optical signal is transmitted. As shown in FIGS. 4 and 5A, the end surface of the core 30a is attached to the end of the optical waveguide array 30. The exposed joint end surface 31 is formed.

  As shown in FIG. 1, when the optical connector 2 is attached to the socket 3 and the cover 4 is attached, the optical axes of the core 20a of the optical waveguide array 20 and the core 30a of the optical waveguide array 30 are aligned, The joining end face 21 of the optical connector 2 and the joining end face 31 of the socket 3 are abutted, and the optical connector 2 is fixed to the socket 3.

  The optical waveguide array 20 and the optical waveguide array 30 are examples of optical waveguides and are planar optical waveguides each having a core / cladding structure. In this example, the optical waveguide array 20 and the optical waveguide array 30 are as shown in FIGS. 2 (a) and 2 (b). In addition, the same number of cores 30a as the plurality of cores 20a are arranged in parallel at a predetermined interval.

  The optical connector 2 includes a joining bottom surface 22 constituted by a plane of the optical waveguide array 20 and aligns the optical waveguide array 20 with respect to the socket 3 on a plane opposite to the joining bottom surface 22 of the optical waveguide array 20. A positioning block 23 as a positioning member is provided.

  The joining end surface 21 of the optical connector 2 is configured such that the end portion of the optical waveguide array 20 exposing the end surface of each core 20 a and one end portion of the positioning block 23 are the same surface orthogonal to the joining bottom surface 22.

  Further, the optical connector 2 includes a pressing surface 24 in which the other end of the positioning block 23 is inclined at approximately 45 degrees with respect to the bonding end surface 21 and the bonding bottom surface 22. Further, the optical connector 2 includes a guide groove 25 on the upper surface of the positioning block 23.

  2 and 3, the guide groove 25 has a V-shaped cross section, for example, and extends from the joint end surface 21 in a direction orthogonal to the direction in which the cores 20a of the optical waveguide array 20 are arranged in parallel. The guide groove 25 is formed at a predetermined position in the direction in which the cores 20a are arranged in parallel, for example, directly above the core 20a located at the center in the parallel direction.

  The socket 3 includes a support substrate 32 that supports the optical waveguide array 30 and the optical connector 2, and the optical waveguide array 30 is mounted on a bonding surface 33 constituted by a plane of the support substrate 32 by bonding or the like. Further, the socket 3 includes a positioning block 34 as a positioning member for aligning the position of the optical connector 2 with respect to the optical waveguide array 30 on a plane opposite to the surface mounted on the joint surface 33 of the optical waveguide array 30.

  The joint end surface 31 of the socket 3 is configured such that one end portion of the optical waveguide array 30 exposing the end surface of each core 30 a and the end portion of the positioning block 34 are the same surface orthogonal to the joint surface 33.

  The socket 3 has a reflection surface 30b in which the other end of the optical waveguide array 30 protrudes from the support substrate 32, and the other end surface of the optical waveguide array 30 is inclined at approximately 45 degrees. In the optical waveguide array 30, the end surface of each core 30a is exposed on the reflection surface 30b, and the light incident on the optical waveguide array 30 from the direction of approximately 90 degrees is totally reflected by the reflection surface 30b and the optical path is bent by approximately 90 degrees. And coupled to the core 30a. The light propagated through the core 30 a is totally reflected by the reflecting surface 30 b, the optical path is bent by approximately 90 degrees, and is emitted in the direction of approximately 90 degrees with respect to the optical waveguide array 30.

  Further, the socket 3 includes a guide groove 35 on the upper surface of the positioning block 34. 2 and 3, the guide groove 35 has the same size and the same shape as the cross-sectional shape of the guide groove 25 formed in the positioning block 23 of the optical connector 2. In this example, the guide groove 35 has a V-shaped cross section. The optical waveguide array 30 extends in a direction perpendicular to the direction in which the cores 30a of the optical waveguide array 30 are arranged in parallel.

  Further, the guide groove 35 is formed in the same positional relationship as the relationship between the optical waveguide array 20 and the positioning block 23 in the optical connector 2 and is a predetermined position in the parallel direction of the cores 30a. It is determined directly above 30a located at the center in the parallel direction.

  In the socket 3, the support substrate 32 on which the optical waveguide array 30 and the positioning block 34 are mounted is mounted on the printed wiring board 10, and the end surface of each core 30 a exposed to the reflective surface 30 b of the optical waveguide array 30 is the printed wiring board. 10 is aligned with the position of the light emitting element 10a mounted on the semiconductor device.

  The socket 3 includes guide portions 36 on the sides of the optical waveguide array 30 and the support substrate 32. The guide portion 36 is erected on both sides of the support substrate 32, and a mounting recess 37 is formed as a mounting portion with the joint surface 33 of the support substrate 32 as a bottom surface. Further, the guide portion 36 is erected on the end portion on the reflection surface 30 b side of the optical waveguide array 30 and covers the light emitting element 10 a together with the optical waveguide array 30 and the support substrate 32. Furthermore, the guide part 36 is provided with the latching recessed part 38 fixed so that the cover 4 can be attached or detached.

  The cover 4 includes a pressing convex portion 40 as an urging means pressed against the pressing surface 24 of the optical connector 2, a positioning convex portion 41 fitted in the guide groove 25 of the optical connector 2 and the guide groove 35 of the socket 3, and the socket 3. The locking claw portion 42 is fitted into the locking recess 38.

  The cover 4 is made of resin, and as shown in FIG. 3, on the back surface of the top plate 43 covering the upper surface of the positioning block 34 of the socket 3 and the positioning block 23 of the optical connector 2 mounted in the mounting recess 37 of the socket 3, The pressing convex portion 40 and the positioning convex portion 41 are formed to protrude, and the locking claw portion 42 is formed on the leg portion that extends from the back surface of the top plate 43.

  The pressing protrusion 40 is pressed against the pressing surface 24 of the optical connector 2 when the optical connector 2 is mounted in the mounting recess 37 of the socket 3 and the locking claw 42 of the cover 4 is fitted in the locking recess 38 of the socket 3. And is configured to be elastically deformed.

  The joining end surface 21 of the optical connector 2 is pressed against the joining end surface 31 of the socket 3 by the inclination of the pressing surface 24 and, for example, a semicircular convex shape of the pressing convex portion 40, and the joining bottom surface 22 of the optical connector 2 is connected to the socket 3. The force which pushes the optical connector 2 is produced in the direction pressed against the joint surface 33.

  When the optical connector 2 is mounted in the mounting recess 37 of the socket 3 and the locking claw portion 42 of the cover 4 is fitted in the locking recess 38 of the socket 3, the positioning convex portion 41 is inserted into the guide groove of the positioning block 34 of the socket 3. 35 and a length that fits in both the guide groove 25 of the positioning block 23 of the optical connector 2 mounted in the mounting recess 37.

  Thus, in the socket 3 and the optical connector 2, the guide groove 25 of the positioning block 23 and the guide groove 35 of the positioning block 34 are arranged in a straight line, and the positions of the optical waveguide array 20 and the optical waveguide array 30 are aligned.

<Operational effect example of the optical transmission module of the present embodiment>
Next, an example of the connection operation of the optical transmission module of the present embodiment will be described with reference to each drawing.

  In the optical transmission module 1A, the optical connector 2 is mounted in the mounting recess 37 of the socket 3, and the locking claw portion 42 of the cover 4 is fitted in the locking recess 38 of the socket 3 in which the optical connector 2 is mounted. In this way, when the cover 4 is attached to the socket 3, the joining end surface 21 of the optical connector 2 and the joining end surface 31 of the socket 3 come into contact with each other, and the optical connector 2 and the socket 3 are light guides provided in the optical connector 2. The optical axes of the core 20a of the waveguide array 20 and the core 30a of the optical waveguide array 30 provided in the socket 3 are aligned and fixed.

  First, the alignment in the Y (lateral) direction along the parallel direction of the cores of each optical waveguide array, which is one direction orthogonal to the optical axis at the joint end face of each optical waveguide array, will be described.

  When the cover 4 is mounted, the optical waveguide array 30 provided in the socket 3 has a positioning projection provided on the back surface of the cover 4 in the guide groove 35 of the positioning block 34 as shown in FIG. 41 is inserted.

  Similarly, when the cover 4 is attached to the optical waveguide array 20 provided in the optical connector 2 attached to the attachment recess 37 of the socket 3, as shown in FIG. The positioning convex portion 41 of the cover 4 is fitted into the groove 25.

  Since the positioning convex portion 41 is linear, the guide groove 25 of the positioning block 23 and the guide groove 35 of the positioning block 34 are arranged linearly. As described above, the optical waveguide array 20 and the optical waveguide array 30 have the same core pitch, the positional relationship in the Y direction between the optical waveguide array 20 and the guide groove 25 in the optical connector 2, and the optical waveguide array 30 in the socket 3. And the guide groove 35 have the same positional relationship in the Y direction.

  Thereby, the guide groove 25 of the optical connector 2 and the guide groove 35 of the socket 3 are arranged in a straight line, so that the position of the optical waveguide array 20 of the optical connector 2 and the optical waveguide array 30 of the socket 3 in the Y (lateral) direction. Are matched.

  Next, alignment in the Z (vertical) direction, which is the other direction orthogonal to the optical axis, at the joint end face of each optical waveguide array will be described.

  The optical waveguide array 30 provided in the socket 3 is fixed to the joint surface 33 of the support substrate 32. The optical waveguide 20 provided in the optical connector 2 is configured such that when the optical connector 2 is mounted in the mounting recess 37 of the socket 3, the bonding bottom surface 22 of the optical waveguide array 20 contacts the bonding surface 33 of the support substrate 32. It has become.

  Further, when the cover 4 is attached to the socket 3 to which the optical connector 2 is attached, the pressing convex portion 40 provided on the back surface of the cover 4 is in contact with the pressing surface 24 of the positioning block 23 and the joining surface 33 of the support substrate 32. The bottom surface 22 of the optical waveguide array 20 is pressed against the optical waveguide array 20.

  That is, as described above, when the cover 4 is attached to the socket 3, the pressing convex portion 40 of the cover 4 is configured to have a size that is pressed against the pressing surface 24 of the optical connector 2 and elastically deformed. Then, due to the inclination of the pressing surface 24 and the convex shape of the pressing convex portion 40, the optical waveguide array 20 is not deformed by the joint bottom surface 22 of the optical waveguide array 20 of the optical connector 2 into the joint surface 33 of the support substrate 32 of the socket 3. By pressing with such a light pressure, the contact state between the optical waveguide array 20 and the support substrate 32 is maintained.

  Next, the alignment in the X (front-rear) direction, which is the direction along the optical axis, at the joint end face of each optical waveguide array will be described.

  When the cover 4 is attached to the socket 3 to which the optical connector 2 is attached, the pressing protrusion 40 on the back surface of the cover 4 comes into contact with the pressing surface 24 of the positioning block 23 as described above, thereby joining the socket 3. The joining end surface 21 of the optical connector 2 is pressed against the end surface 31.

  That is, the joining end surface 21 of the optical connector 2 is configured such that the end surface of the optical waveguide array 20 and the end surface of the positioning block 23 are the same surface, and the joining end surface 31 of the socket 3 is the end surface of the optical waveguide array 30 and the end surface of the positioning block 34. Are configured on the same plane. Further, the bonding end surface 21 and the bonding end surface 31 are surfaces orthogonal to the bonding surface 33 of the support substrate 32.

  As a result, the cover 4 is mounted on the socket 3, and the force generated by the pressing convex portion 40 of the cover 4 being pressed against the pressing surface 24 of the optical connector 2 and elastically deforming is used, so that the optical waveguide array 20 on the joining end surface 21 is formed. The end face and the end face of the optical waveguide array 30 at the joining end face 31 are joined without a gap.

  Then, the light pressure at which the optical waveguide array 20 and the optical waveguide array 30 are not deformed by the joint end surface 21 of the optical connector 2 and the joint end surface 31 of the socket 3 due to the inclination of the pressing surface 24 and the convex shape of the pressing convex portion 40. And the contact state between the optical waveguide array 20 and the optical waveguide array 30 is maintained.

  Therefore, the optical connectors 2 and the sockets 3 are aligned with the optical axes of the optical waveguide array 20 and the optical waveguide array 30, and the aligned state is maintained.

  In this way, the optical waveguide arrays are brought into contact with each other so as to be detachable, so that the optical axis can be aligned with a simple configuration such as abutment between flat surfaces, so that a lens or the like is unnecessary, and the number of parts is reduced. Can be suppressed.

  When the cover 4 is attached to the socket 3, the pressing convex portion 40 provided on the cover 4 is pressed against the pressing surface 24 formed on the positioning block 23 of the optical connector 2 to be elastically deformed, whereby the optical waveguide The optical waveguide array 20 and the optical waveguide array 30 are maintained in contact with each other by being pressed with a light pressure that does not cause deformation of the arrays. Thereby, the influence of the external force and the change of the environment can be suppressed.

  FIG. 6 is a perspective view showing an example of usage of the optical transmission module of the present embodiment, FIG. 7 is a side view showing an example of usage of the optical transmission module of the present embodiment, and FIG. 8 is an optical connector. 9 is an exploded perspective view of the optical transmission module of the present embodiment showing a state in which the optical connector is attached and detached, and FIG. 9 is a partially broken exploded perspective view of the optical transmission module of the present embodiment showing the state in which the optical connector is attached and detached.

  As shown in FIGS. 6 and 7, the optical transmission module 1A includes, for example, a single optical waveguide having a plurality of cores 20a as shown in FIG. 2B between the main printed wiring boards 50A and 50B. The optical connectors 2 are respectively provided at both ends of the optical waveguide array 30 in a configuration in which the arrays 20 are connected.

  The main printed wiring boards 50A and 50B are provided with a socket 3 to which the optical connector 2 is attached and a cover 4 for aligning and fixing the optical connector 2 to the socket 3, respectively.

  As shown in FIG. 8, since the optical connector 2 has a mechanism that can be attached to and detached from the socket 3, the optical waveguide array 20 and the socket 3 provided in the optical connector 2 are connected to the socket 3 as shown in FIG. The provided optical waveguide array 30 can be separated.

  As a result, the optical connector 2 and the socket 3 can select the optical waveguide material that meets the respective conditions. For example, in the optical waveguide array 20 provided in the optical connector 2, as shown in FIG. 6, since it is configured to span between the sockets 3 of the main printed wiring boards 50 </ b> A and 50 </ b> B, a flexible and movable material is used. desirable.

  On the other hand, in the optical waveguide array 30 provided in the socket 3, as shown in FIG. 9, it is fixed to the support substrate 32 and does not need to be flexible, but the main printed wiring boards 50A and 50B (printed wiring boards). A material having high heat resistance is desirable in consideration of the influence of heat caused by soldering or the like that occurs during mounting of the light-emitting element 10a in 10) or an unillustrated light-receiving element or electronic component such as a driver circuit.

  Further, by providing the optical waveguide array 30 on the socket 3 side, when the optical connector 2 is removed, the optical waveguide array 30 can cover the light emitting element 10a and electronic components such as a light receiving element and a driver circuit (not shown). It is also possible to prevent dust and dust from adhering. Furthermore, since it is not necessary to provide a cover such as an electronic component as a separate component, an increase in the number of components can be suppressed, and downsizing can be achieved, and in particular, the height dimension can be suppressed low.

  As described above, the optical transmission module according to the present embodiment has a three-axis alignment structure of X, Y, and Z. However, the optical waveguide array has a configuration that takes into account component variations and built-in tolerances. Next, a description will be given of a configuration that takes into account manufacturing variations of components and installation tolerances.

  First, as shown in FIG. 2, the alignment in the Y (lateral) direction is performed such that the guide groove 25 of the positioning block 23 provided in the optical waveguide array 20 of the optical connector 2 and the positioning block 34 provided in the optical waveguide array 30 of the socket 3. The positioning protrusion 41 provided on the back surface of the cover 4 is fitted into the guide groove 35. With this configuration, highly accurate alignment is possible, but due to mounting errors of the positioning blocks 23 and 34 to the optical waveguide arrays 20 and 30, the positional relationship between the core of the optical waveguide array and the guide groove is displaced. May occur. A structure for allowing this will be described.

  FIG. 10 is a top view of the optical waveguide array between the optical connectors and the optical waveguide array of a pair of sockets. In FIG. 10, it is assumed that the optical signal transmitted in each optical waveguide array travels in the direction of the arrow.

  In each optical waveguide array, the width in the Y (lateral) direction of the core gradually decreases from the input side to the output side. For example, in the optical waveguide array 30 (1) provided in the socket 3 on the output side, the dimension in the Y (lateral) direction on the input side of the core 30a is 40 μm, and the dimension in the Y (lateral) direction on the output side is 30 μm. Next, in the optical waveguide array 20 provided in the pair of optical connectors 2, the dimension of the input side Y (lateral) direction of the core 20a is 60 μm, and the dimension of the output side Y (lateral) direction is 30 μm. Further, in the optical waveguide array 30 (2) provided in the socket 3 on the receiving side, the dimension in the Y (lateral) direction on the input side of the core 30a is 60 μm, and the dimension in the Y (lateral) direction on the output side is 50 μm.

  By providing such a tapered core, the Y (lateral) dimension of the core increases from 30 μm to 60 μm at the connection portion between the output-side optical waveguide array 30 (1) and the transmission-side optical waveguide array 20. . That is, the deviation of the dimension in the Y (lateral) direction has a margin of ± 15 μm. Similarly, at the connection portion between the transmission-side optical waveguide array 20 and the receiving-side optical waveguide array 30 (2), the dimension of the core in the Y (lateral) direction increases from 30 μm to 60 μm. That is, the deviation of the dimension in the Y (lateral) direction has a margin of ± 15 μm.

  The optical waveguide array is manufactured by, for example, a photolithography process, and the shape of the core can be determined by the mask pattern. Therefore, it is easy to form a tapered core.

  Next, alignment in the Z (vertical) direction is performed by directly connecting the optical waveguide array 30 of the socket 3 and the optical waveguide array 20 of the optical connector 2 to the joint surface 33 of the support substrate 32 of the socket 3 as shown in FIG. It is set as the structure made to contact. The positional shift in such a configuration is only an error in the thickness direction of the optical waveguide arrays 20 and 30.

  In a typical optical waveguide, the thickness of the clad under the core is usually about 30 μm, and at least about 10 μm, and a thickness error of about 5 to 10% occurs in the optical waveguide manufacturing process. When the cladding thickness is 10 μm, the cladding thickness error is 0.5 to 1 μm. Although this value is slight as an error, if it is considered that the transmission loss is reduced as much as possible, the error can be absorbed by providing the following configuration.

  FIG. 11 is a side view of the optical waveguide array between the optical connectors and the optical waveguide array of a pair of sockets. In FIG. 11, it is assumed that the optical signal transmitted in each optical waveguide array travels in the direction of the arrow.

  In each optical waveguide array, the dimensions of the core and cladding in the Z (vertical) direction are changed from the input side to the output side. For example, in the optical waveguide array 30 (1) provided in the output-side socket 3, the dimension of the core 30 a in the Z (vertical) direction is set to 40 μm, and then in the optical waveguide array 20 provided in the pair of optical connectors 2, The dimension in the Z (vertical) direction is 45 μm, and in the optical waveguide array 30 provided in the socket 3 on the receiving side, the dimension in the Z (vertical) direction is 50 μm. In each optical waveguide array, the thickness of the optical waveguide array is the same by changing the dimensions of the under cladding layer and the over cladding layer in the Z (vertical) direction according to the core.

  By providing the core with the height changed in this way, the Z (vertical) dimension of the core is changed from 40 μm to 45 μm at the connection portion between the optical waveguide array 30 (1) on the output side and the optical waveguide array 20 on the transmission side. To increase. That is, the deviation of the dimension in the Z (vertical) direction has a margin of ± 2.5 μm. Similarly, the dimension in the Z (vertical) direction of the core increases from 45 μm to 50 μm at the connection portion between the optical waveguide array 20 on the transmission side and the optical waveguide array 30 (2) on the reception side. That is, the deviation of the dimension in the Z (vertical) direction has a margin of ± 2.5 μm.

  The optical waveguide array is manufactured by, for example, a photolithography process, and the Z direction cannot be tapered. However, the thickness of the core and the clad can be controlled at the time of film formation, so that the height of the core is made different. It is easy.

  FIG. 12 is a block diagram illustrating an example of a circuit configuration for realizing the optical transmission module of the present embodiment. The optical transmission module 1A of the present embodiment includes a first transmission system 100 that transmits an optical signal from a first circuit (first electronic component) 90 to a second circuit (second electronic component) 91; And a second transmission system 101 that transmits an optical signal from the second circuit 91 to the first circuit 90.

  The first transmission system 100 includes an optical communication IC (Integrated Circuits) 100a, a driver amplifier 100b, a semiconductor laser 100c as a light emitting element, an optical waveguide 100d as an optical waveguide array 20, a photodiode 100e as a light receiving element, a transimpedance. An amplifier 100f and an optical communication IC 100g are provided.

  In this configuration, the optical communication IC 100a, the driver amplifier 100b, and the semiconductor laser 100c are disposed on the first circuit 90 side, and the photodiode 100e, the transimpedance amplifier 100f, and the optical communication IC 100g are disposed on the second circuit 91 side. The optical waveguide 100d is disposed between the first circuit 90 and the second circuit 91.

  Similarly, the second transmission system 101 includes an optical communication IC 101a, a driver amplifier 101b, a semiconductor laser 101c as a light emitting element, an optical waveguide 101d as an optical waveguide array 20, a photodiode 101e as a light receiving element, a transimpedance amplifier 101f, an optical A communication IC 101g is provided.

  In this configuration, the optical communication IC 101a, the driver amplifier 101b, and the semiconductor laser 101c are disposed on the second circuit 91 side, and the photodiode 101e, the transimpedance amplifier 101f, and the optical communication IC 101g are disposed on the first circuit 90 side, The optical waveguide 101d is disposed between the first circuit 90 and the second circuit 91.

  The optical waveguide 100d and the optical waveguide 101d are connected to the light emitting element and the light receiving element with the configuration described in FIG. The first transmission system 100 and the second transmission system 101 may be realized by independent optical waveguides, or may be realized by a single optical waveguide array having a plurality of cores.

  Next, an operation when data is transmitted from the first circuit 90 to the second circuit 91 will be described. On the first circuit 90 side, data to be transmitted is converted into serial data by the optical communication IC 100a, and this serial data is supplied to the driver amplifier 100b. The semiconductor laser 100c is driven by the driver amplifier 100b supplied with the data to be transmitted, and an optical signal corresponding to the serial data is generated from the semiconductor laser 100c. The output optical signal is transmitted to the second circuit 91 side through the optical waveguide 100d.

  On the second circuit 91 side, the optical signal transmitted through the optical waveguide 100d is received by the photodiode 100e. An electrical signal by photoelectric conversion from the photodiode 100e is supplied to the impedance amplifier 100f, impedance matching is performed, and the transmitted serial data is input to the optical communication IC 100g.

  In this way, data is transmitted from the first circuit 90 to the second circuit 91. Although detailed description is omitted, the operation for transmitting data from the second circuit 91 to the first circuit 90 is similarly performed.

  FIG. 13 is a cross-sectional view schematically showing an example of a mounting structure of an optical element (light emitting element, light receiving element), an optical communication IC, and an amplifier (driver amplifier, transimpedance amplifier) that realizes the optical transmission module of the present embodiment. It is.

  A light emitting element 602a and a driver amplifier 603a are mounted on the surface side of the printed wiring board 601a provided in the optical module 650a. Solder 616a is interposed between the electrode pad 604a on the back surface of the printed wiring board 601a and the electrode pad 606a on the upper surface of the main printed wiring board 605a, and the printed wiring board 601a is soldered on the surface of the main printed wiring board 605a. It is attached.

  In the light emitting element 602a, solder 609a is interposed between the electrode 608a formed on the back surface and the electrode pad 607a on the surface of the printed wiring board 601a, and the light emitting element 602a is soldered on the printed wiring board 601a. Similarly, in driver amplifier 603a, solder 612a is interposed between electrode 611a formed on the back surface and electrode pad 610a on the front surface of printed wiring board 601a, and driver amplifier 603a is soldered on printed wiring board 601a. .

  In the optical communication IC 615a, solder 617a is interposed between the electrode 614a and the electrode pad 613a on the back surface of the main printed wiring board 605a, and the optical communication IC 615a is soldered on the back surface of the main printed wiring board 605a. .

  A light receiving element 602b and a transimpedance amplifier 603b are mounted on the surface side of the printed wiring board 601b provided in the optical module 650b. Solder 606b is interposed between the electrode pad 604b on the back surface of the printed wiring board 601b and the electrode pad 606b on the upper surface of the main printed wiring board 605b, and the printed wiring board 601b is soldered on the surface of the main printed wiring board 605b. It is attached.

  In the light receiving element 602b, solder 609b is interposed between the electrode 608b formed on the back surface and the electrode pad 607b on the surface of the printed wiring board 601b, and the light receiving element 602b is soldered on the printed wiring board 601b. Similarly, in the transimpedance amplifier 603b, solder 612b is interposed between the electrode 611b formed on the back surface and the electrode pad 610b on the front surface of the printed wiring board 601b, and the transimpedance amplifier 603b is soldered on the printed wiring board 601b. Is done.

  In the optical communication IC 615b, solder 617b is interposed between the electrode 614b and the electrode pad 613b on the back surface of the main printed wiring board 605b, and the optical communication IC 615b is soldered on the back surface of the main printed wiring board 605b. .

  Next, the operation of the optical transmission module having the mounting structure described above will be described. On the optical module 650a side, an electrical signal from the optical communication IC 615a passes through the inside of the main printed wiring board 605a, passes through the printed wiring board 601a that is secondarily mounted on the upper surface, and further passes through the upper surface of the printed wiring board 601a. Is supplied to the driver amplifier 611a mounted on the driver. Then, an electric signal is sent from the driver amplifier 611a to the light emitting element 602a, and an optical signal whose intensity is modulated in accordance with the electric signal is generated from the light emitting portion of the light emitting element 602a.

  The optical signal output from the light emitting element 602a is totally reflected by the reflection surface 30b of the optical waveguide array 30 described with reference to FIG. 1 and the like, and transmitted through the core 30a. With the configuration of the socket 3 and the optical connector 2 described with reference to FIG. 1 and the like, the optical waveguide array 30 on the output side and the optical waveguide array 20 for inter-substrate transmission are connected, so that the core 30a of the optical waveguide array 30 is transmitted. Light enters the core 20a of the optical waveguide array 20 and is transmitted through the core 20a.

  Further, by connecting the optical waveguide array 20 and the receiving-side optical waveguide array 30, the light transmitted through the core 20 a of the optical waveguide array 20 is incident on the core 30 a of the receiving-side optical waveguide array 30. 30a is transmitted.

  The optical signal received on the optical module 650b side passes through the core 30a of the receiving-side optical waveguide array 30 and is totally reflected by the reflecting surface 30b. The optical path is changed by approximately 90 degrees and enters the light receiving element 602b.

  The received optical signal is converted into an electrical signal by the light receiving element 602b. An electrical signal corresponding to the optical signal passes through the transimpedance amplifier 603b, passes through the printed wiring board 601b, passes through the main printed wiring board 605b on which the printed wiring board 601b is mounted, and enters the main printed wiring board 605b. It is supplied to the mounted IC 615b for optical communication.

  According to the optical modules 650a and 650b described above, by applying the optical transmission module 1A of the present embodiment, optical elements and the like are mounted on the printed wiring boards 601a and 601b, and the optical connector 2 shown in FIG. The socket 3 to which is attached is mounted. Thereby, the mounting structure of the main printed wiring board can be used as it is by secondary mounting the printed wiring boards 601a and 601b on the existing main printed wiring boards 605a and 605b. Therefore, if an area where the printed wiring boards 601a and 601b can be mounted is provided on the main printed wiring boards 605a and 605b, other electrical components can be formed by a conventional process.

  The optical transmission module provided in the above-described printed wiring boards 601a and 601b fixes the socket, and after completing all mounting processes including high-temperature processes such as solder reflow and underfill resin sealing, Since the optical waveguide array provided in the optical connector only needs to be mounted, even if the optical waveguide array 20 is made of a material that is vulnerable to a high temperature process, it can be mounted without being affected by the high temperature.

  Furthermore, according to the optical modules 650a and 650b described above, the provision of the optical transmission module increases the degree of freedom of electrode arrangement compared to the case where an electrical connector is mounted. As a result, the optical communication ICs 615a and 615b, the driver amplifier 603a and the transimpedance amplifier 603b are mounted close to each other via the printed wiring boards 601a and 601b and the main printed wiring boards 605a and 605b by mounting them on the front and back of the board. Can be installed. Therefore, the wiring length between the optical communication ICs 615a and 615b, the driver amplifier 603a and the transimpedance amplifier 603b can be shortened, and noise countermeasures and crosstalk countermeasures for electric signals can be facilitated, and the light modulation speed can be improved.

  In the example of FIG. 13, the form in which the substrates are connected by the optical waveguide has been described. However, the present invention can also be applied to a form in which one substrate is connected by the optical waveguide.

  The present invention is applied to an optical connector of an optical communication module between boards of electronic equipment or between chips.

It is a sectional side view which shows an example of the optical transmission module of this Embodiment. It is sectional drawing of the optical transmission module of this Embodiment. It is a partially broken exploded perspective view of the optical transmission module of the present embodiment. It is a perspective view of the optical waveguide array which comprises the optical transmission module of this Embodiment. It is an arrow view of the optical transmission module of this Embodiment. It is a perspective view which shows an example of the usage condition of the optical transmission module of this Embodiment. It is a side view which shows an example of the usage condition of the optical transmission module of this Embodiment. It is a disassembled perspective view of the optical transmission module of this Embodiment which shows the state which attached / detached the optical connector. It is a partially broken exploded perspective view of the optical transmission module of the present embodiment showing a state where an optical connector is attached and detached. It is a top view of the optical waveguide array between optical connectors and the optical waveguide array of a pair of sockets. It is a side view of the optical waveguide array between optical connectors and an optical waveguide array of a pair of sockets. It is a block diagram which shows an example of the circuit structure which implement | achieves the optical transmission module of this Embodiment. It is sectional drawing which shows the outline of an example of the mounting structure which implement | achieves the optical transmission module of this Embodiment. It is a block diagram which shows an example of the conventional optical module by an optical connector connection. It is a block diagram which shows an example of the conventional optical module by electrical connector connection.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1A ... Optical transmission module, 10 ... Printed wiring board, 10a ... Light emitting element, 2 ... Optical connector, 20 ... Optical waveguide array, 20a ... Core, 21 ... Joining end surface 22 ... Bonding bottom surface, 23 ... Positioning block, 24 ... Pressing surface, 25 ... Guide groove, 3 ... Socket, 30 ... Optical waveguide array, 30a ... Core, 30b・ ・ ・ Reflecting surface, 31 ... Junction end face, 32 ... Support substrate, 33 ... Joint surface, 34 ... Positioning block, 35 ... Guide groove, 36 ... Guide part, 37 ..Mounting recess, 38... Locking recess, 4 .. cover, 40... Pressing protrusion, 41 .. positioning protrusion, 42 .. locking claw, 43.

Claims (8)

An optical connector having an optical waveguide formed with a joint end face exposing an end face of a core through which an optical signal is transmitted;
A socket having an optical waveguide formed with a joint end face exposing an end face of a core through which an optical signal is transmitted, and having a mounting portion to which the optical waveguide of the optical connector is mounted;
A mounting substrate on which an optical element that is optically coupled to the optical waveguide of the socket is mounted at the end opposite to the joint end surface, and the socket is mounted;
The optical waveguide is detachably mounted on the socket, and the optical waveguide and the joint end surface of the optical waveguide of the optical connector and the optical waveguide of the optical connector and the mounting portion of the socket are in contact with each other. A cover having a biasing means for biasing the connector;
An optical transmission module comprising: positioning means for aligning the optical axes of the cores of the optical waveguide of the optical connector and the optical waveguide of the socket. The positioning means is formed in a guide groove formed in a positioning member provided in the optical waveguide of the socket, a guide groove formed in a positioning member provided in the optical waveguide of the optical connector, and the cover. A positioning convex portion,
When the optical connector is mounted on the mounting portion of the socket and the cover is mounted on the socket, the positioning convex portion is fitted into the guide groove of the socket and the guide groove of the optical connector, and the optical axis The optical transmission module according to claim 1, wherein alignment in a lateral direction perpendicular to the optical axis is performed. The biasing means includes a pressing convex portion formed on the cover, and a pressing surface formed on an end portion of the optical connector opposite to the joining end surface of the positioning member,
When the optical connector is mounted on the mounting portion of the socket and the cover is mounted on the socket, the pressing convex portion is pressed against the pressing surface to be elastically deformed, and the optical waveguide of the optical connector and the optical waveguide The optical transmission module according to claim 2, wherein the optical connector is urged in a direction in which the joint end faces of the optical waveguide of the socket come into contact with each other, and alignment in the front-rear direction along the optical axis is performed. . The positioning means includes a joining bottom surface constituted by a plane of the optical waveguide of the optical connector, and a support substrate having a joining surface on which the optical waveguide of the socket is mounted,
When the optical connector is mounted on the mounting portion of the socket and the cover is mounted on the socket, the pressing convex portion is pressed against the pressing surface to be elastically deformed, and the joining bottom surface of the optical connector and the 4. The optical transmission module according to claim 3, wherein the optical connector is biased in a direction in which the joint surface of the socket comes into contact, and alignment in a vertical direction perpendicular to the optical axis is performed. The optical waveguide of the socket is inclined at an end opposite to the joint end face, reflects light incident from a direction perpendicular to the light transmission direction in the core, and enters the core, and A reflection surface that reflects the light transmitted through the core and emits it from the vertical direction,
The optical transmission module according to claim 1, wherein the optical element is disposed below the reflecting surface of the optical waveguide of the socket and is covered with the optical waveguide. The optical transmission module according to claim 1, wherein an electronic component connected to the optical element is mounted on the mounting substrate. A pair of the mounting boards provided with the socket are mounted on a pair of main boards or one main board, and the optical waveguide provided with the optical connector between the pair of main boards or in one main board The optical transmission module according to claim 6, wherein the optical transmission module is connected by: The optical waveguide of the socket and the optical waveguide of the optical connector are characterized in that the diameter of the core arranged on the input side is larger than the diameter of the core arranged on the output side of the optical signal at the joint end face. The optical transmission module according to claim 1.

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