Optical Transmitter

Abstract

An optical transmitter according to one embodiment comprises a plurality of light emission elements, a plurality of light reception elements which monitor output light from each of the plurality of light emission elements, a housing to which the plurality of light emission elements and the plurality of light reception elements are mounted, and a wiring board provided with a first region which is mounted to the housing and has a pad electrically coupled to the light emission elements and a second region which is disposed at a lower position than the first region and has a pad electrically coupled to the light reception elements.

Description

[Technical Field]

[0001] The present disclosure relates to optical transmitters. This application claims priority to Japanese Application No. 2020-102401 filed on June 12, 2020, and incorporates by reference all of the contents of said Japanese application. [Background technology]

[0002] Patent Document 1 describes a semiconductor light emitting module. The semiconductor light emitting module includes a semiconductor light emitting module main part including a semiconductor light emitting element, and a housing that houses the semiconductor light emitting module main part. The housing is a hermetic type container that has airtightness, and an optical element is mounted inside the container. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-033037 Summary of the Invention

[0004] An optical transmitter according to one embodiment includes a plurality of light-emitting elements, a plurality of light-receiving elements that monitor the output light from each of the plurality of light-emitting elements, a housing that mounts the plurality of light-emitting elements and the plurality of light-receiving elements, and a wiring board that is mounted on the housing and has a first region that has a first pad electrically connected to the light-emitting elements, and a second region that is positioned lower than the first region and has a second pad electrically connected to the light-receiving elements. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a perspective view showing an optical transmitter according to an embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional view of the optical transmitter of FIG. [Figure 3] FIG. 3 is a cross-sectional view showing the optical transmitter of FIG. 1 with the cover removed. [Figure 4] FIG. 4 is a perspective view showing the optical transmitter of FIG. 1 with the cover removed. [Figure 5] 5 is a cross-sectional view showing the housing, wiring board, light-emitting element, and spacer of the optical transmitter of FIG. [Figure 6] FIG. 6 is a plan view showing the optical transmitter of FIG. 1 with the cover removed. [Figure 7] 7 is a cross-sectional view showing the housing, the combiner, the light receiving element, the light emitting element, the wiring board, and the spacer of the optical transmitter of FIG. [Figure 8] FIG. 8 is a diagram schematically showing the positional relationship between the output light from the light-emitting element and the light-receiving element in FIG. [Figure 9] FIG. 9 is a plan view showing a housing, a combiner, a wiring board, a light receiving element, and a light emitting element of an optical transmitter according to a first modified example. [Figure 10] FIG. 10 is a perspective view showing the housing, the combiner, the wiring board, the light receiving element, and the light emitting element of FIG. [Figure 11] FIG. 11 is a plan view showing a housing, a combiner, a wiring board, a light receiving element, and a light emitting element of an optical transmitter according to a first modified example. [Figure 12] FIG. 12 is a cross-sectional view showing the housing, the combiner, the wiring board, the light receiving element, and the light emitting element of FIG. [Figure 13] FIG. 13 is a plan view showing a housing, a combiner, a wiring board, a light receiving element, and a light emitting element of an optical transmitter according to a second modification. [Figure 14] FIG. 14 is an enlarged plan view of a wiring substrate, a light receiving element, and a light emitting element according to a further modification of the second modification. DETAILED DESCRIPTION OF THE INVENTION

[0006] Unlike the hermetic type housing described above, optical transmitters equipped with non-hermetic type (non-airtight) housings are sometimes used to reduce costs. The optical transmitter includes an LD (Laser Diode), a carrier on which the LD is mounted, an FPC (Flexible Printed Circuit) with pads electrically connected to the LD, and a monitor PD (Photo Diode) that monitors the light from the LD.

[0007] The LD is electrically connected to the wiring pattern on the FPC, and the monitor PD is electrically connected to the wiring pattern on the carrier. Optical transmitters are known that mount optical components such as LDs on a metal base without using the carrier. In this type of optical transmitter, it is not possible to provide a wiring pattern on the metal base. Therefore, it is possible to place a carrier with a wiring pattern on the base. However, a configuration in which a carrier is further placed on the base may result in increased costs.

[0008] An object of the present disclosure is to provide an optical transmitter that does not require the placement of a carrier on which a wiring pattern is provided.

[0009] According to the present disclosure, it is possible to eliminate the need to arrange a carrier on which a wiring pattern is provided.

[0010] The contents of the embodiments of the present disclosure will be described below. An optical transmitter according to one embodiment includes a plurality of light-emitting elements, a plurality of light-receiving elements that monitor output light from each of the plurality of light-emitting elements, a housing that mounts the plurality of light-emitting elements and the plurality of light-receiving elements, and a wiring substrate that is mounted on the housing and has a first region that has a first pad that is electrically connected to the light-emitting elements, and a second region that is positioned lower than the first region and has a second pad that is electrically connected to the light-receiving elements.

[0011] In this optical transmitter, a wiring board is mounted on a housing that mounts multiple light-emitting elements and multiple light-receiving elements. The wiring board has a first region having first pads electrically connected to each of the multiple light-emitting elements and a second region having second pads electrically connected to each of the multiple light-receiving elements. Since both the second pads electrically connected to the light-receiving elements and the first pads electrically connected to the light-emitting elements are provided on the wiring board, electrical wiring can be provided on the housing. Even if the housing is made of metal, electrical wiring can be provided on the wiring board extending from the housing, eliminating the need for a carrier or the like with a wiring pattern. As a result, costs can be reduced. The second pads electrically connected to the light-receiving elements are positioned lower than the first pads electrically connected to the light-emitting elements. Therefore, the wiring extending from the light-receiving elements to the second pads is less likely to overlap with the output light, preventing the wiring from interfering with the optical path of the output light. As a result, the output light can be more reliably monitored by the light-receiving elements.

[0012] The plurality of light-emitting elements may be arranged in a line along a first direction, and the plurality of light-receiving elements may be arranged in a line along the first direction. The wiring substrate may have a connection region connecting the first region and the second region to each other. The width of the connection region in the first direction may be narrower than the width of the first region and the width of the second region in the first direction. In this case, the narrow width of the connection region connecting the first region and the second region to each other can suppress an increase in the area of ​​the wiring substrate. This allows for a compact arrangement of components.

[0013] The connection region may extend from an end of the first region in the first direction to an end of the second region in the first direction, in which case the width of the connection region in the first direction can be further narrowed.

[0014] The thickness of the wiring substrate in the first region and the thickness of the wiring substrate in the second region may be the same, and the connection region may have a step or a slope. In this case, the thickness of the wiring substrate in the first region is the same as the thickness of the wiring substrate in the second region, which simplifies the configuration of the wiring substrate.

[0015] The optical transmitter may further include a spacer provided between the first region of the wiring board and the housing. In this case, the spacer is interposed between the first region of the wiring board, which is higher than the second region, and the housing. Therefore, the spacer can hold the first region in a more stable state.

[0016] The optical transmitter described above may further include a cover that covers the housing, and the housing may have guide pins that determine the position of the cover relative to the housing. The wiring board may have an extension region that is on an extension line of the connection region and extends from the second region along a second direction that intersects with the first direction, and holes into which the guide pins are inserted may be formed in the extension region. In this case, the extension region that extends from the connection region of the wiring board can be effectively used as a region in which holes into which the guide pins of the housing are inserted are formed.

[0017] The second pads in the second region of the wiring substrate may be located off the optical axis of the light output from the light emitting element, which further reduces the possibility that the wiring extending from the second pads will interfere with the output light.

[0018] The second pad may be provided outside the optical axis in the second region of the wiring board in the first direction of the housing. In this case, by providing the second pad outside in the first direction, interference with output light from wiring extending from the second pad to the light receiving element can be more reliably suppressed.

[0019] The optical transmitter described above may further include a combiner that combines the output light from each of the multiple light-emitting elements, and a receptacle that is arranged on the optical output side of the housing as viewed from the combiner. The optical axis of the light passing through the receptacle may be the same as the optical axis of the light combined by the combiner, and may be located closer to the end of the housing than the center in the first direction. The connection area may be located closer to the end of the housing than the center in the first direction and on the same side as the receptacle. In this case, the position of the connection area in the first direction can be located on the same side as the receptacle.

[0020] The light receiving element may be a front-illuminated light receiving element, and the mounting surface of the carrier on which the light receiving element is mounted may be inclined, with the light receiving surface of the light receiving element being disposed at an angle to the optical axis of the output light. The second region may be located on the opposite side of the carrier from the light emitting element. In this case, by disposing the light receiving surface at an angle to the optical axis, the front-illuminated light receiving element can monitor a portion of the output light with higher accuracy.

[0021] Specific examples of optical transmitters according to the present disclosure will be described below with reference to the drawings. The present invention is not limited to the examples below, but is defined by the claims, and all modifications within the scope of equivalents to the claims are intended to be included. In the description of the drawings, identical or corresponding elements are designated by the same reference numerals, and redundant descriptions will be omitted as appropriate. For ease of understanding, some parts of the drawings may be simplified or exaggerated, and the dimensional proportions and the like are not limited to those shown in the drawings.

[0022] Fig. 1 is a perspective view showing an optical transmitter 1 according to this embodiment. As shown in Fig. 1, the optical transmitter 1 includes a housing 2, a cover 3 that covers the housing 2, a receptacle 4 with a cylindrical sleeve, and a wiring board 5. The optical transmitter 1 extends along a longitudinal direction D1, with the receptacle 4, cover 3 (housing 2), and wiring board 5 arranged in this order.

[0023] FIG. 2 is a partial cross-sectional view of the optical transmitter 1. As shown in FIGS. 1 and 2, the housing 2 includes a lower plate 2A extending in a longitudinal direction D1 and a side wall 2B extending in a height direction D2 from one end of the lower plate 2A in the longitudinal direction D1. The housing 2 is made of, for example, metal. Examples of the material for the housing 2 include kovar (an alloy of iron containing at least nickel and cobalt) or SUS (stainless used steel). The housing 2 may also be made of iron, chromium, an alloy of iron and chromium, an alloy of iron and nickel, or plastic.

[0024] The housing 2 is L-shaped when viewed from the width direction D3 of the optical transmitter 1. The housing 2 is also referred to as an L-shaped base. A hole into which the receptacle 4 is inserted and which serves as the emission end of the output light L (see FIG. 3) is formed in the side wall 2B, and the hole penetrates the side wall 2B in the longitudinal direction D1. The receptacle 4 is formed in a cylindrical shape. The receptacle 4 has multiple flanges 4c, one of which functions as a guide 4b that determines the position of the receptacle 4. When the receptacle 4 is fixed to the housing 2, for example, the guide 4b comes into contact with the outer surface 2f of the side wall 2B.

[0025] When viewed from the height direction D2, for example, the housing 2 has a rectangular shape. The housing 2 is a component that mounts the components housed inside the optical transmitter 1, and each component of the optical transmitter 1 is mounted on a lower plate 2A. The lower plate 2A has an elongated portion that protrudes from the side wall 2B in the longitudinal direction D1, and each component of the optical transmitter 1 is mounted on this elongated portion. The lower plate 2A has a main surface 2b that faces each component inside the optical transmitter 1, a convex mounting surface 2c on which the components are mounted, guide pins 2d that determine the position of the cover 3 relative to the housing 2, and an outer surface 2f that is exposed to the outside of the optical transmitter 1.

[0026] The main surface 2b has a rectangular shape extending in the longitudinal direction D1 and the width direction D3. The mounting surface 2c is a portion that protrudes from the main surface 2b in the height direction D2. Components such as a combiner 6 that combines light are mounted on the mounting surface 2c. The guide pin 2d protrudes from the main surface 2b in the height direction D2. The guide pin 2d has, for example, a cylindrical shape. The guide pin 2d is provided, for example, on one side in the width direction D3 (at a position offset from the center of the housing 2 in the width direction D3).

[0027] The cover 3 is a component that covers the housing 2 in the height direction D2, and the components of the optical transmitter 1 are housed inside the housing 2 and the cover 3. The cover 3 has an outer surface 3b that is exposed to the outside of the optical transmitter 1 and an inner surface 3c that faces the components of the optical transmitter 1. The inner surface 3c has a convex portion 3d that protrudes toward the guide pin 2d of the housing 2, and a hole portion 3f that is formed inside the convex portion 3d and into which the guide pin 2d fits in the height direction D2. The cover 3 is fixed to the housing 2 by the guide pin 2d fitting into the hole portion 3f.

[0028] 3 is a side view of the housing 2 showing the state in which the cover 3 is removed from the optical transmitter 1. As shown in FIGS. 2 and 3, the optical transmitter 1 includes a wiring board 5, a combiner 6, a light-receiving element 7, a first lens 8, a light-emitting element 9, and a spacer 10 inside the housing 2 and the cover 3. A portion of the wiring board 5 extends from the housing 2 and the cover 3 to the side opposite the receptacle 4. The portion of the wiring board 5 extending to the side opposite the receptacle 4 protrudes outside the optical transmitter 1.

[0029] 4 is a perspective view showing the receptacle 4, the housing 2, and each component of the optical transmitter 1 mounted on the main surface 2b of the housing 2. As shown in FIGS. 3 and 4, the optical transmitter 1 further includes a second lens 11 interposed between the receptacle 4 and the combiner 6. For example, the optical transmitter 1 includes four light-emitting elements 9, four first lenses 8, four light-receiving elements 7, the combiner 6, and the second lens 11.

[0030] The optical transmitter 1 is a four-lane multi-channel light emitting module including four light receiving elements 7, four first lenses 8, and four light receiving elements 7. In the optical transmitter 1 having four lanes of optical paths for the output light L, the optical path length of the output light L differs for each channel. The receptacle 4 is disposed, for example, at a position offset from the center of the housing 2 in the width direction D3. The optical path of the output light L from the light emitting element 9 located at the end opposite the receptacle 4 in the width direction D3 (the upper end in FIG. 4) is the longest. The optical path of the output light L from the light emitting element 9 located at the end on the receptacle 4 side in the width direction D3 (the lower end in FIG. 4) is the shortest.

[0031] The housing 2 is mounted with a plurality of light-emitting elements 9 and a plurality of light-receiving elements 7. The light-emitting elements 9 are arranged side by side along the width direction D3 (first direction), and the light-receiving elements 7 are arranged side by side along the width direction D3. For example, four light-emitting elements 9 are mounted on the main surface 2b of the housing 2 via carriers 12 (first mounting portions). Each light-emitting element 9 is provided corresponding to one of the four first lenses 8 and one of the four light-receiving elements 7. Each light-emitting element 9 is, for example, a semiconductor laser diode (LD). Output light L, which is divergent light output from the light-emitting element 9, is converted into collimated light by each first lens 8.

[0032] A portion of the output light L output from the light-emitting element 9 via the first lens 8 passes through the light-receiving element 7 and enters the combiner 6. The combiner 6 is, for example, an optical combiner that combines four output light L. The four output light L are combined inside the combiner 6 and output from the combiner 6 to the second lens 11 as a single output light L. The second lens 11 focuses the output light L from the combiner 6 and focuses the output light L onto an optical fiber held in the receptacle 4, and the output light L is output to the outside of the optical transmitter 1 via the optical fiber held in the receptacle 4.

[0033] The light receiving element 7 is a monitor PD (Photo Diode) that monitors the output light L from each of the plurality of light emitting elements 9. The light receiving element 7 monitors the intensity of the output light L by receiving a portion of the output light L from the light emitting elements 9. For example, each of the four light receiving elements 7 is mounted on the main surface 2b of the housing 2 via a carrier 13 (second mounting portion) made of a material containing a dielectric, or a protrusion provided on the housing 2.

[0034] The light receiving element 7 converts a portion of the output light L from the light emitting element 9 into an electrical signal and outputs the converted electrical signal to the pad 5b (second pad) of the wiring board 5 via a wire (not shown). The light receiving element 7 and the wire extending from the light receiving element 7 are provided on the optical output side (receptacle 4 side) of the light emitting element 9. The output of this electrical signal from the light receiving element 7 makes it possible to perform APC (Auto Power Control) on the output light L from the light emitting element 9.

[0035] The wiring board 5 is, for example, a flexible printed circuit (FPC) mounted on the housing 2. The housing 2 has a pair of protrusions 2g protruding upward at an end opposite the side wall 2B in the longitudinal direction D1. The pair of protrusions 2g are arranged side by side in the width direction D3. The wiring board 5 has a first region 5A extending outward from the optical transmitter 1, a second region 5B in which pads 5b are provided, and a connection region 5C connecting the first region 5A and the second region 5B to each other. When viewed from the height direction D2, the first region 5A, the second region 5B, and the connection region 5C are U-shaped (C-shaped).

[0036] The first region 5A has recesses 5c at both ends in the width direction D3. The first region 5A has a pair of recesses 5c aligned in the width direction D3, and the wiring board 5 is fixed to the housing 2 by fitting each protrusion 2g of the housing 2 into each recess 5c. The first region 5A has pads 5d (first pads) electrically connected to the light-emitting elements 9. For example, each of the multiple light-emitting elements 9 is electrically connected to the pad 5d via a wire 14. The first region 5A is provided at a higher position (a position farther from the main surface 2b of the housing 2) than the second region 5B, and for example, the height of the first region 5A matches the height of the carrier 12 on which the light-emitting elements 9 are mounted. This allows the length of the wires 14 extending from each light-emitting element 9 to be shortened.

[0037] For example, one wiring board 5 has a first region 5A as an upper stage and a second region 5B as a lower stage, and is fixed to the housing 2 by adhesive. The second region 5B is provided at a lower position than the first region 5A, and is in contact with, for example, the main surface 2b of the housing 2. By positioning the second region 5B low in this way, it is possible to prevent wires extending from the wiring board 5 or the light receiving element 7 from interfering with the output light L passing through the light emitting element 9 and the first lens 8.

[0038] 5 is a vertical cross-sectional view of the housing 2 with the spacer 10 enlarged. As shown in FIG. 5, the spacer 10 is provided between the first region 5A and the housing 2, and, for example, the height of the first region 5A is ensured by the spacer 10. Note that, instead of the spacer 10, a reinforcing plate made of an insulating material may be provided in the first region 5A of the wiring board 5. In this case, it becomes possible to provide a wiring pattern also on the underside of the first region 5A.

[0039] Fig. 6 is a plan view showing the housing 2, receptacle 4, wiring board 5, combiner 6, light receiving element 7, first lens 8, light emitting element 9, and second lens 11. Fig. 7 is a vertical cross-sectional view showing the housing 2, wiring board 5, combiner 6, light receiving element 7, first lens 8, and light emitting element 9. As shown in Figs. 6 and 7, the width (length in the width direction D3) of connection region 5C of wiring board 5 is narrower than the width of first region 5A and the width of second region 5B.

[0040] The connection region 5C is provided, for example, at the end on the receptacle 4 side in the width direction D3 (the lower side in FIG. 6). The connection region 5C extends from the end of the first region 5A in the width direction D3 to the end of the second region 5B in the width direction D3. This allows the receptacle 4 to be positioned inside the end in the width direction D3, rather than at the end in the width direction D3. The thickness of the wiring board 5 in the first region 5A and the thickness of the wiring board 5 in the second region 5B are, for example, the same. The connection region 5C extends in the longitudinal direction D1 between the first region 5A and the second region 5B, and is located, for example, at the end of the housing 2 in the width direction D3. The connection region 5C has a step or slope located between the first region 5A and the second region 5B. In this embodiment, an example is shown in which the connection region 5C has a slope 5f.

[0041] 8 is a side view schematically showing the light receiving element 7, the first lens 8, and the carrier 13. As shown in FIGS. 7 and 8, the second region 5B is a PD wiring FPC having pads 5b for wiring to the light receiving element 7, and is located on the light output side (receptacle 4 side) of the light receiving element 7. The carrier 13 described above has a mounting surface 13b on which the light receiving element 7 is mounted. The mounting surface 13b is disposed obliquely with respect to the optical axis of the output light L from the light emitting element 9 (the optical axis extending from the light emitting element 9 along the longitudinal direction D1).

[0042] The light receiving element 7 is a front-illuminated light receiving element and has a light receiving surface 7b on its surface. Because the mounting surface 13b is disposed at an angle with respect to the optical axis of the output light L, the light receiving surface 7b of the light receiving element 7 is also disposed at an angle with respect to the optical axis of the output light L. The light receiving element 7 is disposed so that the light receiving surface 7b forms an inclination angle θ with respect to the optical axis of the output light L, and thus the light receiving element 7 receives a portion of the output light L.

[0043] By disposing the light receiving element 7 on the optical output side of the light emitting element 9, it becomes possible to monitor the output light L on the optical output side with a simple configuration. Wiring such as wires for the light receiving element 7, which is the monitor PD, is provided on the optical output side of the light receiving element 7. This enables electrical connection with the light receiving element 7 without reducing the light receiving sensitivity of the light receiving element 7. The light receiving element 7 is wired directly to, for example, pad 5b on the wiring board 5, so there is no need to mount a separate carrier or the like. This contributes to cost reduction.

[0044] The effects obtained from the optical transmitter 1 according to this embodiment will be described in detail. In the optical transmitter 1, a wiring board 5 is mounted on a housing 2 that mounts a plurality of light-emitting elements 9 and a plurality of light-receiving elements 7. The wiring board 5 has a first region 5A having pads 5d that are electrically connected to each of the plurality of light-emitting elements 9, and a second region 5B having pads 5b that are electrically connected to each of the plurality of light-receiving elements 7. Therefore, the pads 5b that are electrically connected to the light-receiving elements 7 and the pads 5d that are electrically connected to the light-emitting elements 9 are both provided on a single wiring board 5, so that electrical wiring can be provided on the housing 2.

[0045] Even if the housing 2 is made of metal, electrical wiring can be provided on the wiring board 5 extending from the housing 2, eliminating the need for a carrier or the like provided with a wiring pattern. As a result, increases in costs can be suppressed. The pad 5b electrically connected to the light receiving element 7 is positioned lower than the pad 5d electrically connected to the light emitting element 9. Therefore, wiring such as a wire extending from the light receiving element 7 to the pad 5b is less likely to overlap the output light L, so the wiring does not interfere with the optical path of the output light L. As a result, the output light L can be monitored more reliably at the light receiving element 7.

[0046] The plurality of light-emitting elements 9 may be arranged side by side along the width direction D3, and the plurality of light-receiving elements 7 may be arranged side by side along the width direction D3. The wiring board 5 may have a connection region 5C that connects the first region 5A and the second region 5B to each other. The width of the connection region 5C (the length in the width direction D3) may be narrower than the width of the first region 5A and the width of the second region 5B. In this case, the narrow width of the connection region 5C that connects the first region 5A and the second region 5B to each other can prevent an increase in the area of ​​the wiring board 5. This allows for a compact arrangement of components.

[0047] The connection region 5C may extend from the end of the first region 5A in the width direction D3 to the end of the second region 5B in the width direction D3, in which case the width of the connection region 5C in the width direction D3 can be further narrowed.

[0048] The thickness of the wiring board 5 in the first region 5A and the thickness of the wiring board 5 in the second region 5B may be the same. The connection region 5C may have a step or a slope 5f. In this case, the thickness of the wiring board 5 in the first region 5A is the same as the thickness of the wiring board 5 in the second region 5B, which simplifies the configuration of the wiring board 5.

[0049] The optical transmitter 1 may further include a spacer 10 provided between the first region 5A of the wiring board 5 and the housing 2. In this case, the spacer 10 is interposed between the first region 5A of the wiring board 5, which is higher than the second region 5B, and the housing 2. Therefore, the spacer 10 can hold the first region 5A in a more stable state.

[0050] The optical transmitter 1 may further include a combiner 6 that combines the output light L from each of the multiple light-emitting elements 9, and a receptacle 4 that is arranged on the optical output side of the housing 2 as viewed from the combiner 6. The optical axis of the light passing through the receptacle 4 may be the same as the optical axis of the light combined by the combiner 6, and may be located closer to the edge than the center in the width direction D3 of the housing 2. The connection region 5C may be located closer to the edge than the center in the width direction D3 of the housing 2 and on the same side as the receptacle 4. In this case, the position of the connection region 5C in the width direction D3 can be offset to the same side as the receptacle 4.

[0051] The light receiving element 7 is a front-illuminated light receiving element, and the mounting surface 13b of the carrier 13 on which the light receiving element 7 is mounted may be inclined. The light receiving surface 7b of the light receiving element 7 may be disposed at an angle to the optical axis of the output light L, and the second region 5B may be disposed on the opposite side of the carrier 13 from the light emitting element 9. In this case, by disposing the light receiving surface 7b at an angle to the optical axis of the output light L, the front-illuminated light receiving element 7 can monitor part of the output light L with higher accuracy.

[0052] The housing 2 may be manufactured by metal injection molding (MIM). In this case, the cost of manufacturing the housing 2 can be reduced. In the housing 2, the side wall 2B to which the receptacle 4 is attached and the bottom plate 2A to which the components are mounted are integrated, which reduces the occurrence of component tolerances and enables the housing 2 to have high rigidity. The housing 2 has a pair of protrusions 2g that protrude upward at the end opposite the side wall 2B in the longitudinal direction D1. Therefore, even if the housing 2 with components already installed is accidentally placed upside down, the side wall 2B and the protrusions 2g will come into contact with the floor or the like, preventing the installed components from interfering with the floor or the like.

[0053] An optical transmitter 21 according to a first modified example will be described with reference to FIGS. 9, 10, and 11. FIG. 9 is a plan view showing a wiring board 25 of the optical transmitter 21 according to the first modified example. FIG. 10 is a perspective view showing the housing 2, receptacle 4, wiring board 25, combiner 6, light-receiving element 7, light-emitting element 9, and spacer 10 of the optical transmitter 21. FIG. 11 is a plan view showing the housing 2, receptacle 4, wiring board 25, combiner 6, light-receiving element 7, and light-emitting element 9 of the optical transmitter 21. Since part of the configuration of the optical transmitter 21 is the same as part of the configuration of the optical transmitter 1 described above, a description of the configuration of the optical transmitter 21 that overlaps with the configuration of the optical transmitter 1 will be omitted as appropriate. The same components of the optical transmitter 21 as those of the optical transmitter 1 will be described using the same reference numerals.

[0054] In addition to the first region 5A, second region 5B, and connection region 5C described above, wiring board 25 has extension region 25A that extends further from connection region 5C in longitudinal direction D1. Extension region 25A protrudes, for example, from second region 5B to the opposite side of connection region 5C. Holes 25c into which guide pins 2d of housing 2 are inserted are formed in extension region 25A, and holes 25c penetrate in height direction D2.

[0055] The wiring board 25 includes a first region 5A and a second region 5B, similar to the wiring board 5 described above. Pads 25b (second pads) to which wires 7d from the light-receiving elements 7 are connected are provided in the second region 5B. For example, two wires 7d and two pads 25b are provided per light-receiving element 7. The two wires 7d and two pads 25b are provided at positions that are away from the optical axis of the output light L. For example, the wires 7d and the pads 25b are provided at positions that do not overlap with the optical axis of the output light L when viewed from the height direction D2.

[0056] Like the optical transmitter 1, the optical transmitter 21 according to the first modification includes a cover 3 that covers a housing 2, and the housing 2 has guide pins 2d that determine the position of the cover 3 relative to the housing 2. The wiring board 25 has an extension region 25A that is on an extension line of the connection region 5C and extends from the second region 5B along a longitudinal direction D1 (second direction) that intersects with the width direction D3, and a hole 25c into which the guide pin 2d is inserted is formed in the extension region 25A. Therefore, the extension region 25A that extends from the connection region 5C of the wiring board 25 can be effectively used as a region into which the guide pin 2d of the housing 2 is inserted.

[0057] The pads 25b in the second region 5B of the wiring board 25 are provided at positions that are off the optical axis of the output light L from the light emitting element 9. This further reduces the possibility that the wires 7d extending from the pads 25b will interfere with the output light L.

[0058] An optical transmitter 31 according to a second modified example will be described with reference to Figs. 12, 13, and 14. Fig. 12 is a vertical cross-sectional view of the housing 2 showing the receptacle 4, wiring board 35, combiner 6, light receiving element 7, and light emitting element 9 of the optical transmitter 31. Fig. 13 is a plan view showing the wiring board 35, light receiving element 7, first lens 8, and light emitting element 9. Fig. 14 is a plan view showing yet another modified example of the second modified example of the wiring board 35 of Fig. 13.

[0059] 13, an optical transmitter 31 according to the second modification has a wiring board 35 having a different shape from the previously described wiring board 5, and differs from the previously described example in the manner of wires 37d extending from the light-receiving element 7. Similar to the previously described wiring board 25, the wiring board 35 has a first region 5A, a second region 5B, and a connection region 35C. The wiring board 35 may further have an extension region 35D. When viewed from the height direction D2, the first region 5A, the second region 5B, and the connection region 35C are U-shaped.

[0060] However, the orientation of the U-shape formed by the first region 5A, the second region 5B, and the connection region 35C is opposite to the orientation of the U-shape formed by the first region 5A, the second region 5B, and the connection region 5C described above. That is, the positions of the connection region 35C and the extension region 35D in the width direction D3 are different from the positions of the connection region 5C and the extension region 25A in the width direction D3. Accordingly, in the optical transmitter 31, the offset of the receptacle from the center in the width direction D3 is opposite to the offset of the receptacle 4 described above. That is, the receptacle 4 of the optical transmitter 31 is offset from the center in the width direction D3 to the same side as the connection region 35C and the extension region 35D (the upper side in FIGS. 13 and 14 ).

[0061] 14, pads 35b (second pads) to which wires 37d from the light-receiving element 7 are connected are provided in the second region 5B of the wiring board 35. The two wires 37d and the two pads 35b are provided at positions away from the optical axis of the output light L. That is, similar to the optical transmitter 21 described above, the wires 37d and pads 35b are provided at positions that do not overlap with the optical axis of the output light L when viewed from the height direction D2. The wires 37d extending from the light-receiving element 7 extend obliquely from the center in the width direction D3 toward the outside of the housing 2 in the width direction D3.

[0062] In the optical transmitter 31 according to the second modification and a further modification of the second modification, the pad 35b is provided outside the width direction D3 of the optical axis of the output light L in the second region 5B of the wiring board 35. Therefore, by providing the pad 35b outside the width direction D3, interference of the wire 37d extending from the pad 35b to the light receiving element 7 with the output light L can be more reliably suppressed.

[0063] The above describes an embodiment of an optical transmitter according to the present disclosure. However, the present invention is not limited to the above-described embodiment. In other words, those skilled in the art will readily recognize that various modifications and variations are possible within the scope of the appended claims. For example, the shape, size, number, material, and arrangement of each component of the optical transmitter are not limited to those described above and can be modified as appropriate. For example, the above describes the optical transmitter 1, optical transmitter 21, and optical transmitter 31 as optical transmitters according to the embodiment. However, an optical transmitter may be formed by combining partial components of the optical transmitter 1, optical transmitter 21, and optical transmitter 31. [Explanation of symbols]

[0064] 1, 21, 31...Optical transmitter 2. Housing 2A…Lower plate 2B…Side wall 2b…main surface 2c...Mounting surface 2d...Guide pin 2f...Outer surface 2g…Protrusion 3...Cover 3b…External surface 3c…Interior 3d...Convex part 3f…hole part 4...Receptacle 4b... Guide 4c...Flange 5, 25, 35...wiring board 5A…First area 5b, 25b, 35b...Pad (2nd pad) 5B…Second area 5C, 35C...Connection area 5c...recess 5d...Pad (1st pad) 5f…slope 6…Synthesizer 7...Photodetector 7b…Light receiving surface 7d, 37d...wire 8...First lens 9...Light emitting element 10...Spacer 11...Second lens 12, 13…Career 13b...Mounting surface 14...Wire 25A,35D…extension area 25c…hole D1...Longitudinal direction (second direction) D2: Height direction D3: Width direction (first direction) L...Output light

Claims

1. A plurality of light-emitting elements; a plurality of light receiving elements that monitor output light from each of the plurality of light emitting elements; a housing that mounts the plurality of light-emitting elements and the plurality of light-receiving elements; a wiring substrate mounted on the housing, the wiring substrate having a first region having a first pad electrically connected to the light-emitting element, a second region having a second pad electrically connected to the light-receiving element, and a connection region connecting the first region and the second region; Equipped with the plurality of light-emitting elements and the plurality of light-receiving elements are arranged to be aligned along a first direction intersecting an optical axis, The first region and the second region are provided to sandwich the plurality of light-emitting elements and the plurality of light-receiving elements. Optical transmitter.

2. an optical multiplexer mounted on the housing, receiving output light from the plurality of light-emitting elements from a plurality of input terminals provided on one side, multiplexing the input output light, and outputting the multiplexed light to one output terminal provided on another side opposite the one side and offset from the center of the other side; a light introduction port provided in the housing and disposed near the center of the width of the housing, into which the multiplexed light output from the output end of the optical multiplexer is introduced, 2. The optical transmitter according to claim 1.

3. a width in the first direction of the connection region is narrower than a width in the first direction of the first region and a width in the first direction of the second region, the connection region of the wiring board is arranged in a region on the surface of the housing where the light emitting elements and the light receiving elements are not arranged, by offsetting the plurality of light emitting elements and the plurality of light receiving elements to positions corresponding to the input terminals of the optical multiplexer; 3. The optical transmitter according to claim 2.

4. The second region is disposed at a lower position than the first region, a thickness of the wiring substrate in the first region and a thickness of the wiring substrate in the second region are the same, and the connection region has a step or a slope; 4. The optical transmitter according to claim 1.

5. the light introduction port is disposed on a side of the center of the width of the housing where the connection area of ​​the wiring board is located.

3. The optical transmitter according to claim 2.

6. Further provided is a cover that covers the housing, the housing has a guide pin that determines the position of the cover relative to the housing; the wiring substrate has an extension region that is on an extension line of the connection region and extends from the second region along a second direction that intersects with the first direction, A hole into which the guide pin is inserted is formed in the extension region.

6. The optical transmitter according to claim 1.

7. the second pad in the second region of the wiring substrate is provided at a position deviated from the optical axis of the output light from the light emitting element; 7. The optical transmitter according to claim 1.

8. the second pad is provided on the second region of the wiring board outside the optical axis in the first direction of the housing; 8. The optical transmitter according to claim 7.

9. the light receiving element is a front-illuminated light receiving element, a mounting surface of the carrier on which the light receiving element is mounted is inclined, and a light receiving surface of the light receiving element is disposed obliquely with respect to an optical axis of the output light; the second region is located on the opposite side of the carrier from the light emitting element; 9. The optical transmitter according to claim 1.

10. a plurality of first optical elements; a plurality of second optical elements optically coupled to the plurality of first optical elements; a housing that mounts the plurality of first optical elements and the plurality of second optical elements; a wiring substrate mounted on the housing, the wiring substrate having a first region having a first pad electrically connected to the first optical element, a second region having a second pad electrically connected to the second optical element, and a connection region connecting the first region and the second region; Equipped with the plurality of first optical elements and the plurality of second optical elements are arranged to be aligned along a first direction intersecting an optical axis, The optical device, wherein the first region and the second region are provided to sandwich the plurality of first optical elements and the plurality of second optical elements.

11. a receptacle provided in the housing and positioned near the center of the width of the housing; an optical component mounted on the housing, the optical component having a plurality of first ends provided on one side and optically coupled to the plurality of first optical elements, and a second end provided on another side opposite the one side, the second end being positioned offset from the center of the other side and optically coupled to the receptacle; Further provided with 11. The optical device according to claim 10.

12. a width in the first direction of the connection region is narrower than a width in the first direction of the first region and a width in the first direction of the second region, the connection region of the wiring board is arranged in a region on the surface of the housing where the first optical elements and the second optical elements are not arranged by offsetting the plurality of first optical elements and the second optical elements to positions corresponding to the first ends of the optical components; 12. The optical device according to claim 11.

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