Optical semiconductor device

Abstract

To enable miniaturization of optical semiconductor devices that incorporate optical semiconductor elements on a substrate.SOLUTION: An optical semiconductor device has a substrate on which optical semiconductor elements are mounted, a first optical system mounted on the first surface of the substrate, which changes the direction of the optical axis of the optical semiconductor element so that it passes through the substrate, and a second optical system coupled to the optical axis passing through the substrate.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to optical semiconductor devices. [Background technology]

[0002] Patent Document 1 discloses an optical module that includes a chip carrier that mounts a tunable laser element that emits laser light and a temperature detection element, a photodetector that detects the laser light output from the tunable laser element, a temperature control element that mounts the chip carrier and the photodetector element, and a housing that houses the temperature control element and has a window through which the laser light is output. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-13831 Summary of the Invention [Problem to be solved by the invention]

[0004] Optical semiconductor devices are used that include an optical semiconductor element, such as a semiconductor laser element, on a substrate. In addition to the semiconductor laser element, various optical components are mounted on the substrate of such optical semiconductor devices and are arranged on the optical path of light emitted from the semiconductor laser element. Meanwhile, there is an increasing demand for miniaturization of optical semiconductor devices.

[0005] An object of the present disclosure is to enable miniaturization of an optical semiconductor device having an optical semiconductor element on a substrate. [Means for solving the problem]

[0006] An optical semiconductor device according to one embodiment of the present disclosure includes a substrate on which an optical semiconductor element is mounted, a first optical system mounted on a first surface of the substrate and changing the optical axis of the optical semiconductor element to a direction passing through the substrate, and a second optical system coupled to the optical axis passing through the substrate. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to reduce the size of an optical semiconductor device that includes an optical semiconductor element on a substrate. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing the configuration of an optical semiconductor device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a plan view of the optical semiconductor device. [Figure 3] FIG. 3 is a bottom view of the optical semiconductor device. [Figure 4] FIG. 4 is a side cross-sectional view of the optical semiconductor device. [Figure 5] FIG. 5 is a diagram showing a state in which the substrate of the optical semiconductor device has been removed. [Figure 6] FIG. 6 is a perspective view showing a housing provided in the optical semiconductor device. [Figure 7] FIG. 7 is a side cross-sectional view of an optical semiconductor device including a housing. [Figure 8] FIG. 8 is a side cross-sectional view showing a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] First, the contents of the embodiments of the present disclosure will be listed and explained. [1] An optical semiconductor device according to one embodiment of the present disclosure includes a substrate on which an optical semiconductor element is mounted, a first optical system mounted on a first surface of the substrate and changing the optical axis of the optical semiconductor element to a direction passing through the substrate, and a second optical system coupled to the optical axis passing through the substrate.

[0010] [2] In the optical semiconductor device of [1] above, the substrate may be provided with a hole corresponding to an optical axis passing through the substrate.

[0011] [3] In the optical semiconductor device of [1] or [2] above, the optical axis passing through the substrate may be transmitted through the substrate.

[0012] [4] In the optical semiconductor device according to any one of [1] to [3] above, the second optical system may extract output light from the optical semiconductor element to the outside.

[0013] [5] In the optical semiconductor device according to any one of [1] to [4] above, the second optical system may have an optical axis passing through the substrate to the first surface side of the substrate.

[0014] [6] In the optical semiconductor device of [5] above, the optical axis that passes through the first surface side of the substrate may be coupled with a third optical system that is disposed on the first surface side. [Details of the embodiments of the present disclosure]

[0015] Specific examples of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. In the following description, the same elements in the description of the drawings will be given the same reference numerals, and duplicate explanations will be omitted.

[0016] FIG. 1 is a perspective view showing a configuration of an optical semiconductor device 1 according to an embodiment of the present disclosure. FIG. 2 is a plan view of the optical semiconductor device 1. FIG. 3 is a bottom view of the optical semiconductor device 1. FIG. 4 is a side cross-sectional view of the optical semiconductor device 1. FIG. 5 is a diagram showing a state in which the substrate 2 of the optical semiconductor device 1 has been removed. As shown in FIGS. 1 to 5, the optical semiconductor device 1 according to this embodiment includes the substrate 2, an optical semiconductor element 3, a mirror member 5, and a mirror member 6. The mirror member 5 is the first optical system in this embodiment. The mirror member 6 is included in the second optical system in this embodiment.

[0017] The substrate 2 is a dielectric substrate, such as a ceramic substrate. The substrate 2 is made of at least one of silicon (Si), glass, and aluminum nitride (AlN). The substrate 2 may be made of low-temperature co-fired ceramics (LTCC). When the substrate 2 is a glass substrate, vias may be formed in the substrate 2 and a thermally conductive material such as copper (Cu) may be embedded in the vias to enhance heat dissipation. The substrate 2 has a first surface 2a and a second surface 2b facing the opposite side to the first surface 2a. The first surface 2a is the bottom surface of a cavity (recess) formed in the main surface 2c of the substrate 2. The first surface 2a is a flat surface extending along direction D1 (first direction). The second surface 2b is the back surface of the substrate 2. The second surface 2b is a flat surface extending along direction D2 (second direction). In one example, the second surface 2b is parallel to the first surface 2a.

[0018] The optical semiconductor element 3 is disposed on the first surface 2a of the substrate 2 and is mounted on the upper surface of a carrier member 4 provided on the first surface 2a. The optical semiconductor element 3 emits light L1 along direction D1. The optical semiconductor element 3 is, for example, a semiconductor laser element. In this case, the optical semiconductor element 3 has a laser resonator extending along direction D2 and emits laser light as light L1 in direction D1. The optical semiconductor element 3 may be a wavelength-tunable laser element. The waveguide of the optical semiconductor element 3 is provided obliquely with respect to the longitudinal direction of the optical semiconductor element 3 to suppress reflected light at the end face of the optical semiconductor element 3. Therefore, the emission direction of light L1 is oblique with respect to the longitudinal direction of the optical semiconductor element 3. Each of the numerous electrodes of the optical semiconductor element 3 is electrically connected to each of the numerous wirings provided on the main surface 3c.

[0019] The mirror member 5 is mounted on the first surface 2a of the substrate 2 and fixed to the first surface 2a. The mirror member 5 changes the optical axis of the optical semiconductor element 3 to a direction that passes through the substrate 2. That is, the mirror member 5 is optically coupled to the optical semiconductor element 3, receives the light L1 output from the optical semiconductor element 3, and directs the propagation direction of the light L1 toward the second surface 2b of the substrate 2. The mirror member 5 is, for example, a member that is transparent to the wavelength of the light L1 and is a prism having an inclined surface that reflects the light L1. The optical axis of the light L1 passes through the substrate 2. In this embodiment, the optical axis of the light L1 is transmitted through the substrate 2 and passes through the substrate 2.

[0020] The mirror member 6 is mounted on the second surface 2b of the substrate 2 and fixed to the second surface 2b. The mirror member 6 is coupled to an optical axis passing through the substrate 2. That is, the mirror member 6 is optically coupled to the mirror member 5 with the substrate 2 sandwiched therebetween, and directs the light L1 that has passed through the mirror member 5 in a direction D2 along the second surface 2b. Here, the direction D2 is a direction that is a reflection of the direction D1. Specifically, the vector of the direction D2 forms an angle θ greater than 90° (more preferably, greater than 150°) with the vector of the direction D1 (see FIG. 2). The vector of the direction D2 forms an angle θ less than 180° with the vector of the direction D1. A vector that forms an angle of 180° with the vector of the direction D1 refers to a vector that is in the opposite direction to the vector of the direction D1. That is, in this embodiment, when viewed from the thickness direction of the substrate 2, the optical path of the light L1 on the second surface 2b is inclined with respect to the optical path of the light L1 on the first surface 2a. The mirror member 6 is, for example, a member that is transparent to the wavelength of the light L1 and is a prism having an inclined surface that reflects the light L1. The mirror member 6 may be made of the same material as the mirror member 5 and may have the same shape as the mirror member 5. The mirror member 6 may be configured to extract the output light L1 of the optical semiconductor element 3 to the outside of the optical semiconductor device 1.

[0021] The optical semiconductor device 1 further includes an optical fiber 7. The optical fiber 7 is configured so that light L1 (in this embodiment, as will be described later, light L3, which is the remaining part of light L1 branched by the mirror member 8) that has passed through the mirror member 6 is incident on an end face of the optical fiber 7. In the illustrated example, the end face of the optical fiber 7 is positioned in direction D2 relative to the mirror member 6. When viewed from the normal direction of the first surface 2a, the end face of the optical fiber 7 is positioned closer to the optical semiconductor element 3 than the mirror members 5 and 6 (see FIG. 5). An end portion of the optical fiber 7, including the end face, is held by a holding member 14. In the illustrated example, the holding member 14 is placed on the second surface 2b of the substrate 2 and fixed to the second surface 2b. The holding member 14 is made of, for example, glass.

[0022] The optical semiconductor device 1 further includes a mirror member 8, a mirror member 9, a photodetector element 10, an etalon filter 11, and a photodetector element 22. The mirror member 8 is included in the second optical system in this embodiment. The mirror member 8 is disposed on the second surface 2b of the substrate 2 and fixed to the second surface 2b. The mirror member 8 branches light L2, which is a portion of light L1 that has passed through the mirror member 6, from the light L1 and directs the propagation direction of the light L2 toward the first surface 2a of the substrate 2. The mirror member 8 is, for example, a member that is transparent to the wavelength of the light L1 and is a prism having an inclined surface that reflects the light L1. In this way, the second optical system may pass the optical axis of the light L1 through the substrate 2 toward the first surface 2a of the substrate 2.

[0023] The mirror member 9 is the third optical system in this embodiment. The mirror member 9 is disposed on the first surface 2a of the substrate 2 and is fixed to the first surface 2a. The mirror member 9 is optically coupled to the mirror member 8 with the substrate 2 sandwiched therebetween, and directs the light L2 that has passed through the mirror member 8 in a direction along the first surface 2a. In the illustrated example, the mirror member 9 directs the light L2 in the direction D2. The mirror member 9 is, for example, a member that is transparent to the wavelength of the light L2 and is a prism having an inclined surface that reflects the light L2. The mirror member 9 may be made of the same material as the mirror member 8 and may have the same shape as the mirror member 8.

[0024] The photodetector element 10 is disposed on the first surface 2a of the substrate 2 and is mounted on the side surface of a carrier member 13 provided on the first surface 2a. The photodetector element 10 is optically coupled to the mirror member 9. The photodetector element 10 receives light L2 that has passed through the mirror member 8 and outputs an electrical signal corresponding to the intensity of the light L2. The photodetector element 10 is, for example, a photodiode. In this way, by disposing the photodetector element 10 on the first surface 2a together with the optical semiconductor element 3, it is possible to easily electrically connect the photodetector element 10 to wiring provided on the main surface 3c.

[0025] The etalon filter 11 is disposed on the optical path between the mirror member 8 and the photodetector element 10. In the illustrated example, the etalon filter 11 is disposed on the first surface 2a on the optical path between the mirror member 9 and the photodetector element 10, and is fixed to the first surface 2a. The etalon filter 11 has high light transmittance at periodic wavelengths, and is used to fix the emission wavelength of the optical semiconductor element 3.

[0026] The photodetector element 22 is disposed on the first surface 2a of the substrate 2 and is fixed to the first surface 2a. The photodetector element 22 is disposed alongside the mirror member 5 in the direction D1, and outputs an electrical signal corresponding to the intensity of the light L1 that has passed through the light reflecting surface of the mirror member 5. This makes it possible to know the intensity of the light L1. The emission wavelength of the optical semiconductor element 3 is maintained by maximizing the ratio between the intensity of the light L1 and the intensity of the light L2 that has passed through the etalon filter 11 and is detected by the photodetector element 10.

[0027] The optical semiconductor device 1 further includes an isolator 21, a collimating lens 23, and a condensing lens 24. The isolator 21 is disposed on the first surface 2a on the optical path of the light L1. The isolator 21 prevents the light L1 from returning to the optical semiconductor element 3. The collimating lens 23 is disposed on the first surface 2a on the optical path of the light L1 between the optical semiconductor element 3 and the mirror member 5 (between the optical semiconductor element 3 and the isolator 21 in the illustrated example). The collimating lens 23 collimates the light L1 emitted from the optical semiconductor element 3. The condensing lens 24 is disposed on the second surface 2b on the optical path of the light L3 between the mirror member 6 and the end face of the optical fiber 7 (between the mirror member 8 and the end face of the optical fiber 7 in the illustrated example). The condensing lens 24 condenses the light L3 toward the end face of the optical fiber 7.

[0028] 1 and 2, the optical semiconductor device 1 further includes a flexible substrate 51. The flexible substrate 51 has a plurality of terminals. Each of the many terminals of the flexible substrate 51 is electrically connected to a corresponding one of the many wires provided on the main surface 2c of the substrate 2.

[0029] 4, the optical semiconductor device 1 further includes a lid 27. The lid 27 is disposed opposite the first surface 2a of the substrate 2 and airtightly covers the entire surface of the substrate 2, including the first surface 2a. The lid 27 is made of the same material as the substrate 2.

[0030] Fig. 6 is a perspective view showing a housing 40 included in the optical semiconductor device 1. Fig. 7 is a side cross-sectional view of the optical semiconductor device 1 including the housing 40. As shown in Figs. 6 and 7, the optical semiconductor device 1 further includes a housing 40. The housing 40 has a substantially rectangular box shape and houses the substrate 2 and the like therein. A slit 41 is formed in the housing 40, and the optical fiber 7 is inserted through the slit 41 during assembly.

[0031] 7, the optical semiconductor device 1 further includes a temperature control element 12. The temperature control element 12 is disposed on the second surface 2b of the substrate 2 at a position facing the optical semiconductor element 3. The temperature control element 12 is a Peltier element. A plate 12a on the heat absorption side of the Peltier element is in thermal contact with the second surface 2b of the substrate 2. A plate 12b on the heat dissipation side of the Peltier element is in thermal contact with the housing 40. An electrode 52a and an electrode 52b for supplying power to the Peltier element are provided on the plate 12b. A member 53 for supporting the flexible substrate 51 is also provided on the plate 12b.

[0032] The effects obtained by the optical semiconductor device 1 of this embodiment having the above configuration will be described. In the optical semiconductor device of this embodiment, light L1 emitted from the optical semiconductor element 3 on the first surface 2a of the substrate 2 along the first surface 2a is guided by the mirror member 5 to the opposite surface (second surface 2b) of the substrate 2, and is further guided by the mirror member 6 in a direction D2 along the second surface 2b. At this time, the vector of direction D2 forms an angle θ greater than 90° with respect to the vector of direction D1, so the propagation directions of light L1 on the first surface 2a and light L1 on the second surface 2b are opposite or nearly opposite to each other. In this way, by folding the optical path using both surfaces (first surface 2a and second surface 2b) of the substrate 2, the optical semiconductor device 1 can be made smaller.

[0033] As in the present embodiment, the optical semiconductor device 1 may further include an optical fiber 7 having an end face located closer to the optical semiconductor element 3 than the mirror members 5 and 6 when viewed from the normal direction of the first surface 2a. The optical semiconductor device 1 may be configured so that the light L1 (light L3 in this embodiment) that has passed through the mirror member 6 is incident on the end face of the optical fiber 7. In this case, the light L1 that has been bent back by the mirror members 5 and 6 can be guided to the outside of the optical semiconductor device 1.

[0034] As in this embodiment, the optical semiconductor device 1 may include: a mirror member 8 disposed on the second surface 2b of the substrate 2, which branches light L2, a portion of light L1 that has passed through the mirror member 6, from light L1 and directs the propagation direction of light L2 toward the first surface 2a of the substrate 2; a photodetector 10 disposed on the first surface 2a of the substrate 2, which receives light L2 that has passed through the mirror member 8 and outputs an electrical signal corresponding to the intensity of light L2; and an etalon filter 11 disposed on the optical path between the mirror member 8 and the photodetector 10. In this case, the mirror member 8 that branches light L1 and the photodetector 10 that detects the branched light L2 can be disposed on different surfaces. This allows the optical semiconductor device 1 to be miniaturized.

[0035] As in this embodiment, the vector of direction D2 may form an angle θ less than 180° with respect to the vector of direction D1. Here, two vectors forming an angle less than 180° means that the straight lines along each vector are inclined relative to each other. In other words, when the vector of direction D2 forms an angle less than 180° with respect to the vector of direction D1, it means that the optical path on second surface 2b is inclined with respect to the optical path on first surface 2a. In this case, the optical path on second surface 2b deviates from optical semiconductor element 3 when viewed from the normal direction of second surface 2b, making it possible to arrange a component that should be located close to optical semiconductor element 3, such as temperature control element 12, in the area of ​​second surface 2b that overlaps with optical semiconductor element 3.

[0036] As in this embodiment, the optical semiconductor element 3 may have a laser resonator extending along direction D2 and emit laser light as light L1 in direction D1. By setting the extension direction of the laser resonator of the optical semiconductor element 3 to direction D2 in this manner, the longitudinal direction of the optical semiconductor element 3 is aligned with the optical path on the second surface 2b. This makes it possible to secure a large space on the second surface 2b for components that should be placed close to the optical semiconductor element 3.

[0037] As in the present embodiment, the optical semiconductor device 1 may include a temperature control element 12 disposed at a position facing the optical semiconductor element 3 on the second surface 2b of the substrate 2. This makes it possible to control the emission wavelength of the optical semiconductor element 3.

[0038] [Variations] 8 is a side cross-sectional view showing a modified example of the above embodiment. In the above embodiment, light L1 reflected by mirror member 5 passes through substrate 2 to reach mirror member 6, but in this example, a hole (opening 2d) is provided in substrate 2 to correspond to the optical axis passing through substrate 2. Light L1 passes through transparent substrate (transparent member) 31 and opening 2d formed in substrate 2 to reach mirror member 6.

[0039] Specifically, the substrate 2 of this modified example is composed of two layers (a lower layer 2A and an upper layer 2B). The surface of the upper layer 2B opposite the lower layer 2A constitutes the first surface 2a. The surface of the lower layer 2A opposite the upper layer 2B constitutes the second surface 2b. An opening 2d is formed in the lower layer 2A, and an opening 2e wider than the opening 2d is formed in the upper layer 2B at a position overlapping the opening 2d. A transparent substrate 31 is fixed to the surface of the lower layer 2A exposed through the opening 2e with an adhesive 32 so as to close the opening 2d. This hermetically seals the opening 2d. The transparent substrate 31 is, for example, a glass substrate or a sapphire substrate. An anti-reflection film (AR coating) may be provided on the surface of the transparent substrate 31. The adhesive 32 is, for example, low-melting-point glass or a metal-based brazing material such as AuSn solder. The mirror member 5 is disposed on the transparent substrate 31. The transparent substrate 31 has a light transmittance of 90% or more at the wavelength of the light L1.

[0040] As in this modification, by propagating light L1 through transparent substrate 31, it is possible to reduce loss of light L1 compared to when light L1 is transmitted through substrate 2. In particular, when substrate 2 is made of aluminum nitride (AlN), the configuration of this modification is effective because aluminum nitride has lower optical transparency than glass and silicon.

[0041] The optical semiconductor device according to the present disclosure is not limited to the above-described embodiments and modifications, and various other modifications are possible. For example, the above-described embodiments illustrate a case in which the angle θ between the vector of direction D1 and the vector of direction D2 is less than 180°, i.e., the optical path of light L1 on the second surface 2b is inclined with respect to the optical path of light L1 on the first surface 2a. However, if there is no need to place a temperature control element 12, the angle θ between the vector of direction D1 and the vector of direction D2 may be 180°, i.e., the optical path of light L1 on the second surface 2b may be parallel to the optical path of light L1 on the first surface 2a.

[0042] Furthermore, in the above embodiment, the end face of the optical fiber 7 is disposed on the second surface 2b of the substrate 2, but the end face of the optical fiber 7 may be disposed on the first surface 2a of the substrate 2. In that case, it is preferable to further provide a mirror member on the second surface 2b that reflects the light L1 (or light L3) propagating on the second surface 2b toward the first surface 2a. [Explanation of symbols]

[0043] 1...Optical semiconductor device 2...Substrate 2A…lower layer 2B…upper layer 2a…Side 1 2b…Second side 2c…main surface 2d,2e…Aperture 3...Optical semiconductor element 4...Carrier member 5,6...Mirror parts 7...Optical fiber 8,9...Mirror parts 10...Photodetector element 11...Etalon filter 12...Temperature control element 12a,12b...board 13...Carrier member 14...Holding member 21...Isolator 22...Photodetector element 23...Collimating lens 24...Condenser lens 27...Lid 31...Transparent substrate 32...Adhesive 40…Case 41...Slit 51...Flexible board 52a,52b...electrode 53...Components D1…direction (first direction) D2…direction (second direction) L1, L2, L3...light θ…Angle

Claims

1. a substrate on which an optical semiconductor element is mounted; a first optical system mounted on a first surface of the substrate and configured to change the optical axis of the optical semiconductor element to a direction passing through the substrate; a second optical system coupled to the optical axis passing through the substrate.

2. 2. The optical semiconductor device according to claim 1, wherein the substrate is provided with a hole corresponding to the optical axis passing through the substrate.

3. 3. The optical semiconductor device according to claim 1, wherein the optical axis passing through the substrate is transmitted through the substrate and passes through the substrate.

4. The optical semiconductor device according to claim 1 , wherein the second optical system extracts output light from the optical semiconductor element to the outside.

5. 2. The optical semiconductor device according to claim 1, wherein the second optical system passes the optical axis through the substrate to the first surface side of the substrate.

6. The optical semiconductor device according to claim 5 , wherein the optical axis that passes through the first surface side of the substrate is coupled with a third optical system that is disposed on the first surface side.

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