Semiconductor laser module and optical communication device

Abstract

A semiconductor laser module is provided with: a semiconductor laser element (1); an optical branching substrate (2) comprising an input waveguide (21) on which the laser light output from the semiconductor laser element (1) is incident, and a branching section (22) for branching the waveguide into a plurality of output waveguides (23a, 23b), the optical branching substrate (2) outputting the laser light from each of the plurality of output waveguides (23a, 23b), the optical branching substrate (2) comprising a dielectric; and a plurality of optical fibers (3a, 3b) to which each of the plurality of laser beams outputted from the plurality of output waveguides (23a, 23b) is coupled.

Description

Technical Field

[0001] This application relates to semiconductor laser modules and optical communication devices. Background Technology

[0002] To address the increasing speed of communication, co-packaged optics have been proposed (e.g., Patent Document 1). In co-packaged optics, to suppress the degradation of semiconductor laser characteristics caused by the temperature rise of the ASIC (Application Specific Integrated Circuit) within the central unit (co-packaged chip), a semiconductor laser module is placed at a location away from the co-packaged chip. The output light from the semiconductor laser module is coupled via optical fiber to the PIC (Photonic Integrated Circuit) within the co-packaged chip.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: European Patent Application Publication No. 3979524

[0006] Patent Document 2: Japanese Patent Application Publication No. 2002-244078 Summary of the Invention

[0007] In co-packaged optics, optical fibers are used for the optical coupling between the semiconductor laser module and the PIC, making it impossible to utilize light exceeding the fiber's damage threshold. Therefore, when using semiconductor laser elements with light output exceeding the fiber's damage threshold, it is necessary to branch the light within the semiconductor laser module to reduce its intensity before coupling it to the optical fiber. One method for branching the light is, for example, the method using a space optical system as described in Patent Document 2; however, this introduces the problem of increasing the size of the semiconductor laser module due to the space optical system.

[0008] This application was made to solve the above-mentioned problems, and its purpose is to provide a miniaturized semiconductor laser module that will not damage the optical fiber even when the laser output from the semiconductor laser element has a light intensity that exceeds the damage threshold of the optical fiber.

[0009] This application discloses a semiconductor laser module, comprising:

[0010] Semiconductor laser components;

[0011] An optical branching substrate includes an input waveguide coupled with laser light output from a semiconductor laser element, and a branch portion that branches the input waveguide into a plurality of output waveguides, from which laser light is output. The optical branching substrate is made of a dielectric material.

[0012] Multiple optical fibers are coupled to each of the multiple lasers output from the multiple output waveguides.

[0013] According to this application, a miniaturized semiconductor laser module is obtained that will not damage the optical fiber even when the laser output from the semiconductor laser has a light intensity exceeding the damage threshold of the optical fiber. Attached Figure Description

[0014] Figure 1 This is a schematic perspective view showing the structure of the semiconductor laser module according to Embodiment 1.

[0015] Figure 2A This is a top view showing the structure of the optical branching substrate of the semiconductor laser module according to Embodiment 1.

[0016] Figure 2B This illustrates the structure of the optical branching substrate of the semiconductor laser module according to Embodiment 1. Figure 2A A cross-sectional view at position AA.

[0017] Figure 2C This illustrates the structure of the optical branching substrate of the semiconductor laser module according to Embodiment 1. Figure 2A A cross-sectional view at the BB location.

[0018] Figure 2D This illustrates the structure of the optical branching substrate of the semiconductor laser module according to Embodiment 1. Figure 2A A cross-sectional view at the CC position.

[0019] Figure 3 This is a top view showing other structures of the optical branching substrate of the semiconductor laser module according to Embodiment 1.

[0020] Figure 4 This is a top view showing further structures of the optical branching substrate of the semiconductor laser module according to Embodiment 1.

[0021] Figure 5 This is a top view showing further structures of the optical branching substrate of the semiconductor laser module according to Embodiment 1.

[0022] Figure 6 This is a top view showing further structures of the optical branching substrate of the semiconductor laser module according to Embodiment 1.

[0023] Figure 7 This is an enlarged perspective view showing an example of the structure of the laser incident portion of the optical branching substrate of the semiconductor laser module according to Embodiment 1.

[0024] Figure 8 This is an enlarged top view showing another example of the structure of the laser incident portion of the optical branching substrate of the semiconductor laser module according to Embodiment 1.

[0025] Figure 9A This is an enlarged top view showing a further example of the structure of the laser incident portion of the optical branching substrate of the semiconductor laser module according to Embodiment 1.

[0026] Figure 9B It utilizes the optical branching substrate of the semiconductor laser module according to Embodiment 1. Figure 9A The cross-sectional view at position AA is a schematic diagram showing the coupling of the laser.

[0027] Figure 9C This is a schematic diagram showing, using an enlarged cross-sectional view, how the output light is coupled to an optical fiber using a diffraction grating structure in the laser output section of the optical branching substrate of the semiconductor laser module according to Embodiment 1.

[0028] Figure 10A This is a schematic perspective view showing further structures of the semiconductor laser module according to Embodiment 1.

[0029] Figure 10B It utilizes the semiconductor laser module described in Embodiment 1. Figure 10A The cross-sectional view of the optical axis, which includes semiconductor laser elements, is a schematic diagram illustrating the coupling of the laser.

[0030] Figure 10C It utilizes the method described in Implementation 1. Figure 10A as well as Figure 10B The enlarged cross-sectional view of the active layer of the semiconductor laser element in the structure of the semiconductor laser module is a schematic diagram showing the coupling of the laser.

[0031] Figure 11 This is an enlarged perspective view showing an example of the structure of the coupling portion of the optical branch substrate of the semiconductor laser module according to Embodiment 1 with the optical fiber.

[0032] Figure 12 This is a top view showing another example of the structure of the output portion of the optical branching substrate of the semiconductor laser module according to Embodiment 1.

[0033] Figure 13This is a schematic perspective view showing the structure of the semiconductor laser module according to Embodiment 2.

[0034] Figure 14 This is a schematic perspective view showing the structure of the semiconductor laser module according to Embodiment 3.

[0035] Figure 15 This is a schematic perspective view showing the structure of the semiconductor laser module according to Embodiment 4.

[0036] Figure 16 This is a diagram showing the schematic structure of the optical communication device according to Embodiment 5. Detailed Implementation

[0037] Implementation method 1.

[0038] Figure 1 This is a schematic perspective view showing the structure of the semiconductor laser module 100 according to Embodiment 1. The semiconductor laser module 100 includes at least a semiconductor laser element 1, an optical branching substrate 2 formed of a plate-shaped dielectric, and two optical fibers 3a and 3b. The optical branching substrate 2 is disposed between the semiconductor laser element 1 and the optical fibers 3a and 3b. In the semiconductor laser module 100, the laser output from the semiconductor laser element 1 is optically coupled to the input waveguide 21 of the optical branching substrate 2, and is branched into two output waveguides 23a and 23b in the branching section 22. The laser output from the output waveguides 23a and 23b is optically coupled to the optical fibers 3a and 3b, respectively. As will be described later, the number of output waveguides and the number of optical fibers are not limited to two, and two or more are acceptable.

[0039] Semiconductor laser element 1 is a device that generates laser oscillation by applying an electric current. That is, semiconductor laser element 1 is a laser-outputting element. Various laser structures, such as distributed feedback lasers, external resonator lasers, photonic crystal lasers, and photonic crystal surface-emitting lasers, can be used as semiconductor laser element 1. The optical branching substrate 2 is configured such that its laser damage threshold is higher than that of optical fibers 3a and 3b. Therefore, even if the light intensity of the laser output from semiconductor laser element 1 is higher than the damage threshold of optical fibers 3a or 3b, optical coupling can be achieved without damaging optical fibers 3a and 3b by branching the light with the optical branching substrate 2 in a manner lower than the damage threshold of the optical fibers.

[0040] The optical branch substrate 2 is a component that receives laser light output from semiconductor laser element 1, branches it into multiple waveguides, and optically couples it to multiple optical fibers. Figures 2A-2D The detailed structure of the light branch substrate 2 is shown. Figure 2A This is a top view of the optical branch substrate 2. Figure 2B yes Figure 2A A cross-sectional view at position AA. Figure 2C yes Figure 2A Cross-sectional view at the BB location. Figure 2D yes Figure 2A A cross-sectional view at the CC position. (See image below.) Figure 2A As shown, a waveguide consisting of an input waveguide 21, a branch portion 22, and two output waveguides 23a and 23b branched by the branch portion 22 is formed on the optical branch substrate 2. Figure 2B , Figure 2C , Figure 2D As shown in the cross-sectional views, the optical branch substrate 2 has a Si-based structure such as SOI (Silicon On Insulator) or SiN. Inside the first dielectric layer 20b formed on the surface of the plate-shaped dielectric substrate 20a of Si or SiN, a waveguide of the optical branch substrate 2 is formed using a second dielectric material with a higher refractive index than the first dielectric layer 20b.

[0041] In the waveguide of optical branch substrate 2 ( Figure 2B , Figure 2C Input waveguide 21 Figure 2D Surrounding the output waveguides 23a and 23b, a first dielectric layer 20b serving as the cladding is provided, for example, a SiO2 layer (wavelength 1310 nm and refractive index approximately 1.45). The waveguide is formed using a second dielectric material surrounded by this cladding, which has a higher refractive index than the cladding. As the second dielectric material, Si (wavelength 1310 nm and refractive index approximately 3.50) or SiN (wavelength 1310 nm and refractive index approximately 1.99) is used. Utilizing the refractive index difference between the second dielectric material constituting the waveguide and the SiO2 layer serving as the cladding, if the waveguide is Si, a small waveguide size of, for example, 220 nm in height and 500 nm in width can be used; if the waveguide is SiN, a small waveguide size of, for example, 400 nm in width and 1000 nm in width can be used. Similarly, branches such as MMI couplers, directional couplers, and bent waveguides can also be miniaturized. Therefore, by using an optical branching substrate 2 in the branching of the laser output from the semiconductor laser element 1, the optical branching section can be miniaturized compared to the case of using conventional space optical systems. In the case of using conventional space optical systems in the branching of the laser from the semiconductor laser element 1, it is difficult to mount semiconductor laser modules (e.g., QSFP-DD (36mm length) or OSFP (75.5mm length)) into a housing. However, by using an optical branching substrate 2 in the branching of the laser from the semiconductor laser element 1 as shown in this application, the semiconductor laser module can be mounted into a housing.

[0042] exist Figure 2A The diagram shows a structure where an input waveguide 21 branches into two output waveguides 23a and 23b in a branch section 22 composed of Y-branched waveguides. The structure can have multiple output waveguides, meaning the branch section is not limited to... Figure 2A The structure shown can be used in Figure 3 The 1×2 MMI (Multi-Mode Interference) coupler shown as branch 22a in the middle, Figure 4 The directional coupler is shown as a branch 22b in the diagram. When the number of branches is three or more, i.e., the number of output waveguides is three or more, the branches can also be configured as follows: Figure 5 As shown in branch 22c, multiple Y-branch waveguides are used, with more than three output waveguides 23, or as in... Figure 6 The structure shown in Figure 22d uses a 1×N MMI coupler to branch into N output waveguides 23. Of course, it can also be configured as a combination. Figure 2A Y-branch waveguide 22, Figure 3 1×2 MMI coupler 22a, or Figure 6 1×N MMI coupler 22d, Figure 4 The directional coupler 22b branches into three or more output waveguides. The number of branches is preferably selected in such a way that the light intensity is less than the damage threshold of the fiber. However, in the case of using fiber optic connectors consisting of multiple fibers, such as MPO (Multi-fiber Push On) connectors, the number of branches can also be set to match the number of fibers.

[0043] Furthermore, the advantage of using an optical branch substrate 2, rather than an optical fiber, to receive laser light from the semiconductor laser element 1 lies in the freedom of waveguide design. For example, in a single-mode fiber, the mode field diameter is fixed at 9.2 μm at a wavelength of 1310 nm. In contrast, in the waveguide formed on the optical branch substrate 2, the mode field diameter can be adjusted by appropriately designing the waveguide structure. For example, by setting... Figure 7 The light spot size converter 31 shown changes the width and height of the waveguide towards the incident end face 34 of the light branch substrate 2, or as shown in the figure. Figure 8 As shown, a window structure 32 without a waveguide is provided near the incident end face 34, which allows for adjustment of the mode field diameter. By appropriately adjusting the mode field diameter using the design of the optical branch substrate 2, the optical density at the incident end face of the optical branch substrate 2 can be reduced compared to optical fiber, enabling coupling of light with a higher coupling strength than the damage threshold of optical fiber.

[0044] Similarly, by also setting on the injection end face Figure 7 The light spot size converter 31 shown, or Figure 8The window configuration 32 shown can adjust the mode field diameter. By making the mode field diameter of the output end face close to that of the optical fiber, the coupling efficiency between the output waveguide and the optical fiber can be improved.

[0045] In addition, in order to optically couple the semiconductor laser element 1 and the optical branching substrate 2, a [structure / structure] can also be formed on the optical branching substrate 2. Figure 9A and as Figure 9A Cross-sectional view at position AA Figure 9B The diffraction grating structure 41 is shown. Incident laser light from the semiconductor laser element 1 is coupled to the diffraction grating structure 41 and transmitted to the input waveguide 21. In this case, the laser light is incident from the upper surface of the optical branching substrate 2, so compared to the case where the laser light is incident from the end face of the optical branching substrate 2, the laser module can be miniaturized. Furthermore, as... Figure 9C As shown, in the part where the output light of the optical branch substrate 2 is coupled to the optical fiber 3, the laser can also be coupled using the diffraction grating structure 41.

[0046] Furthermore, in order to optically couple the semiconductor laser element 1 and the optical branching substrate 2, the semiconductor laser element 1 can also be disposed on the optical branching substrate 2, and the laser output from the semiconductor laser element 1 and the input waveguide 21 can be optically coupled using evanescent light permeating from the active layer 11 of the semiconductor laser element 1. Figure 10A A schematic diagram showing a perspective view and a cross-sectional view of the optical axis of the laser including semiconductor laser element 1. Figure 10B And a schematic diagram showing a cross-sectional view of the active layer 11 including the semiconductor laser element 1. Figure 10C The structure is shown in the figure. According to this structure, the coupling efficiency between the semiconductor laser element 1 and the optical branch substrate 2 can be improved and the semiconductor laser module can be miniaturized, depending on whether the light is incident from the end face of the optical branch substrate 2 or when the diffraction grating structure 41 is formed on the optical branch substrate 2.

[0047] The optical fiber is a component that receives laser light output from the output waveguide of the optical branch substrate 2 and guides it to the PIC. The optical fiber is positioned to match the output waveguide of the optical branch substrate 2. To simplify the installation of the optical fiber, it can also be installed on the emitting end face of the optical branch substrate 2. Figure 11 The slot 25 is shown. (As shown) Figure 11 As shown, installation can be simplified by setting optical fiber 3 in slot 25.

[0048] The optical fiber does not need to be configured with the same number of output waveguides as the optical branch substrate 2. A portion of the output waveguides of the optical branch substrate 2 can also be used as an output for monitoring the output of the semiconductor laser element 1, or as an output for wavelength monitoring. In this case, for example... Figure 12As shown, it can also be configured to use a directional coupler to extract light with a weaker intensity than the output waveguide 23a from the output waveguide 23a coupled to the optical fiber and send it to the output waveguide 23c as an output for output monitoring or wavelength monitoring.

[0049] Implementation method 2.

[0050] Figure 13 This is a schematic diagram of the semiconductor laser module 600 according to Embodiment 2. The semiconductor laser module 600 includes at least a semiconductor laser element 1, an optical branching substrate 2, optical fibers 3a and 3b, and a focusing lens 4. The focusing lens 4 is disposed between the semiconductor laser element 1 and the optical branching substrate 2, and the optical branching substrate 2, which includes an input waveguide 21, a branching portion 22, and output waveguides 23a and 23b branched from the branching portion 22, is disposed between the focusing lens 4 and the optical fibers 3a and 3b. In the semiconductor laser module 600, the laser light from the semiconductor laser element 1 is optically coupled to the input waveguide 21 after being focused by the focusing lens 4, and after branching into two output waveguides 23a and 23b in the branching portion 22, the laser light output from the output waveguides 23a and 23b is optically coupled to the optical fibers 3a and 3b, respectively. As the optical branching substrate 2, various optical branching substrates described in Embodiment 1 can be used, and the number of output waveguides is not limited to two; of course, there can be more than two output waveguides.

[0051] The focusing lens 4 is a component that focuses the laser light from the semiconductor laser element 1 and reduces the mode size. By reducing the mode size of the laser light from the semiconductor laser element 1 and appropriately designing the waveguide structure of the optical branching substrate 2 to match it, the coupling efficiency between the semiconductor laser element 1 and the optical branching substrate 2 can be improved.

[0052] Implementation method 3.

[0053] Figure 14This is a schematic diagram of the semiconductor laser module 700 according to Embodiment 3. The semiconductor laser module 700 has two semiconductor laser elements 1a and 1b, an optical branching substrate 2a, and four optical fibers 3a1, 3b1, 3a2, and 3b2. The optical branching substrate 2a includes: a first branching unit 2a1, which is composed of a branch 221 following the input waveguide 211, and output waveguides 23a1 and 23b1 branched by the branch 221; and a second branching unit 2a2, which is composed of a branch 222 following the input waveguide 212, and output waveguides 23a2 and 23b2 branched by the branch 222. Laser from the semiconductor laser element 1a is coupled to the input waveguide 211, laser output from the output waveguide 23a1 is optically coupled to the optical fiber 3a1, and laser output from the output waveguide 23b1 is optically coupled to the optical fiber 3b1. Similarly, laser light from semiconductor laser element 1b is coupled to input waveguide 212, laser light output from output waveguide 23a2 is optically coupled to fiber 3a2, and laser light output from output waveguide 23b2 is optically coupled to fiber 3b2. Figure 14 The diagram illustrates an example where an input waveguide is branched into two output waveguides in the first branch unit 2a1 and the second branch unit 2a2. However, the number of output waveguides is not limited to two; a structure with three or more branches is also possible. Furthermore, in... Figure 14 In this configuration, the first branch unit 2a1 and the second branch unit 2a2 are disposed on a single optical branch substrate 2a, but they can also be disposed on separate optical branch substrates. In this case, the structure of the branches, or the structure of the incident end face and the emission end face, of each optical branch substrate need not be the same.

[0054] The semiconductor laser module 700 described in Embodiment 3 can increase the total intensity of light output from the semiconductor laser module 700 by having two or more semiconductor laser elements.

[0055] Implementation method 4.

[0056] Figure 15This is a schematic diagram of the semiconductor laser module 800 according to Embodiment 4. The semiconductor laser module 800 includes a semiconductor laser element (semiconductor laser array element) 1c that outputs two laser beams, an optical branching substrate 2a, and four optical fibers 3a1, 3b1, 3a2, and 3b2. The optical branching substrate 2a is disposed between the semiconductor laser element 1c and the optical fibers. The optical branching substrate 2a in the semiconductor laser module 800 has the same structure as the optical branching substrate 2a described in Embodiment 3, having a first branching unit 2a1 and a second branching unit 2a2. Each laser beam output from the semiconductor laser element 1c is optically coupled to input waveguides 211 and 212, and branches to two output waveguides 23a1 and 23b1, and output waveguides 23a2 and 23b2, respectively. The laser beams output from each output waveguide are optically coupled to optical fibers 3a1, 3b1, 3a2, and 3b2, respectively. Figure 15 The diagram illustrates a semiconductor laser element 1c that outputs two laser beams, but it is not limited to two; it can also be a semiconductor laser element (semiconductor laser array) that outputs three or more laser beams. The number of input waveguides on the optical branching substrate, i.e., the number of branching units, is set corresponding to the number of laser beams output. Figure 15 The diagram illustrates an example where an input waveguide is branched into two output waveguides in the first branch unit 2a1 and the second branch unit 2a2. However, the number of output waveguides is not limited to two; a structure with three or more branches is also possible. Furthermore, in... Figure 15 In this configuration, the first branch unit 2a1 and the second branch unit 2a2 are disposed on a single optical branch substrate 2a, but they can also be disposed on separate optical branch substrates. In this case, the structure of the branches, or the structure of the incident end face and the emission end face, of each optical branch substrate need not be the same.

[0057] According to the semiconductor laser module of this embodiment 5, by having a semiconductor laser element 1c that outputs two or more lasers, the total intensity of light output from the semiconductor laser module can be increased.

[0058] Implementation method 5.

[0059] Figure 16 This is a schematic structural diagram of the optical communication device 900 according to Embodiment 5. In the optical communication device 900, as... Figure 16 The semiconductor laser module 91 includes any one of the semiconductor laser modules described in embodiments 1 to 4. Figure 16In this embodiment, besides the semiconductor laser module 91 and the optical fiber 92, only the PIC 94, ASIC 95, and electronic circuitry 96 connecting the PIC 94 and ASIC 95 within the co-packaged chip 93 are shown. However, other components required for an optical communication device are sometimes also included. In the optical communication device 900, light is transmitted from the semiconductor laser module 91 to the PIC 94 via multiple optical fibers 92. Conventionally, the total intensity of light transmitted from a single semiconductor laser module to the PIC is limited by the damage threshold of the optical fiber. However, with the structure of this embodiment, light intensity exceeding the damage threshold of the optical fiber can be transmitted to the PIC. Furthermore, by using the semiconductor laser module 91, even when the light is branched within the semiconductor laser module, semiconductor laser elements, light branching methods (light branching substrates), and optical fibers can be mounted in the housing (e.g., QSFP-DD (36mm length), OSFP (75.5mm length), etc.) of the semiconductor laser module used in co-packaged optics.

[0060] Furthermore, according to the structure of this embodiment, the semiconductor laser module 91 and the co-packaged chip 93 are connected by an optical fiber 92, thus increasing the physical distance between the semiconductor laser module 91 and the co-packaged chip 93. Therefore, since the physical distance between the semiconductor laser module 91 and the ASIC 95 can be increased, the effect of suppressing the degradation of semiconductor laser characteristics caused by the temperature rise of the ASIC 95 within the co-packaged chip 93, which is one of the objectives of conventional co-package optics, is also ensured.

[0061] This application describes various exemplary embodiments and examples; however, the various features, methods, and functions described in one or more embodiments are not limited to application in a specific embodiment and can be applied to embodiments individually or in various combinations. Therefore, within the scope of the technology disclosed in this application, numerous variations not illustrated are contemplated. For example, these include variations of at least one constituent element, addition of at least one constituent element, omission of at least one constituent element, and extraction of at least one constituent element combined with constituent elements of other embodiments.

[0062] (Symbol Explanation)

[0063] 1, 1a, 1b, 1c: Semiconductor laser element; 2, 2a: Optical branch substrate; 3, 3a, 3b, 3a1, 3a2, 3b1, 3b2, 92: Optical fiber; 4: Focusing lens; 41: Diffraction grating structure; 20a: Dielectric substrate; 20b: First dielectric layer; 21, 211, 212: Input waveguide; 22, 22a, 22b, 22c, 22d, 221, 222: Branch section; 23, 23a, 23b, 23a1, 23a2, 23b1, 23b2: Output waveguide; 25: Slot; 31: Spot size converter; 32: Window structure; 100, 600, 700, 800, 91: Semiconductor laser module; 900: Optical communication device.

Claims

1. A semiconductor laser module, comprising: Semiconductor laser components; An optical branching substrate includes an input waveguide coupled with laser light output from a semiconductor laser element, and a branch portion that branches the input waveguide into a plurality of output waveguides, from which laser light is output. The optical branching substrate is made of a dielectric material. Multiple optical fibers are coupled to each of the multiple lasers output from the multiple output waveguides.

2. The semiconductor laser module according to claim 1, wherein, The optical damage threshold of each of the plurality of optical fibers is a value lower than the maximum light intensity of the laser emitted from the semiconductor laser element.

3. The semiconductor laser module according to claim 1 or 2, wherein, The optical branching substrate includes a dielectric substrate and a first dielectric layer formed on the surface of the dielectric substrate. Inside the first dielectric layer, the input waveguide, the branch, and the output waveguide are formed using a second dielectric material with a refractive index higher than that of the first dielectric layer.

4. The semiconductor laser module according to claim 3, wherein, The material of the first dielectric layer is SiO2, and the material of the second dielectric layer is Si or SiN.

5. The semiconductor laser module according to any one of claims 1 to 4, wherein, The laser is coupled to the input waveguide via a window structure.

6. The semiconductor laser module according to any one of claims 1 to 4, wherein, The portion of the input waveguide to which the laser is coupled has a spot size converter.

7. The semiconductor laser module according to any one of claims 1 to 4, wherein, The input side of the input waveguide has a diffraction grating structure, and the laser output from the semiconductor laser element is coupled to the diffraction grating structure and transmitted to the input waveguide.

8. The semiconductor laser module according to any one of claims 1 to 4, wherein, The laser output from the semiconductor laser element has an evanescent wave, which is coupled to the input waveguide.

9. The semiconductor laser module according to any one of claims 1 to 4, wherein, The laser output from the semiconductor laser element is coupled to the input waveguide via a lens.

10. The semiconductor laser module according to any one of claims 1 to 9, wherein, Slots are provided at various positions on the optical branching substrate where lasers are output from each of the plurality of output waveguides, and each of the plurality of optical fibers is arranged in these slots.

11. An optical communication device comprising a semiconductor laser module as described in any one of claims 1 to 10.

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