Semiconductor laser module and optical communication device

Abstract

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

Description

Technical Field

[0001] The present application relates to a semiconductor laser module and an optical communication device.

Background Art

[0002] In order to cope with the increase in communication speed, a method called Co-packaged optics has been proposed (for example, Patent Document 1). In Co-packaged optics, in order to suppress the characteristic degradation of the semiconductor laser due to the temperature rise of the ASIC (Application Specific Integrated Circuit) in the central unit (Co-packaged chip), a semiconductor laser module is provided at a position away from the Co-packaged chip, and the output light from the semiconductor laser module is coupled to the PIC (Photonic Integrated Circuit) in the Co-packaged chip through an optical fiber.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In co-packaged optics, optical fibers are used for the optical coupling between the semiconductor laser module and the PIC, meaning that light exceeding the optical fiber's damage threshold cannot be used. Therefore, when using a semiconductor laser element with an optical output exceeding the optical fiber's damage threshold, it is necessary to split the light within the semiconductor laser module, reduce its intensity, and then couple it to the optical fiber. One method for splitting the light is to use a spatial optical system, as described in Patent Document 2, but this method presents the challenge of increasing the size of the semiconductor laser module.

[0005] This invention was made to solve the above-mentioned problems, and aims to provide a semiconductor laser module that can be miniaturized and does not damage the optical fiber even when the laser light output from the semiconductor laser element has an optical intensity that exceeds the optical fiber damage threshold. [Means for solving the problem]

[0006] The semiconductor laser module disclosed herein comprises a semiconductor laser element, The optical branching substrate comprises an input waveguide to which the laser light output from the semiconductor laser element is coupled, and a branching section that branches the input waveguide into a plurality of output waveguides, wherein laser light is output from each of the plurality of output waveguides, and the optical branching substrate is made of a dielectric material. The system comprises multiple optical fibers, each of which combines the laser beams output from the multiple output waveguides. [Effects of the Invention]

[0007] According to this invention, a semiconductor laser module can be obtained that does not damage the optical fiber even when the laser light output from the semiconductor laser has an optical intensity exceeding the optical fiber damage threshold, and that can be miniaturized. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic perspective view showing the configuration of a semiconductor laser module according to Embodiment 1. [Figure 2A] This is a plan view showing the configuration of the optical branching substrate of a semiconductor laser module according to Embodiment 1. [Figure 2B] This is a cross-sectional view at position AA in Figure 2A, showing the configuration of the optical branching substrate of the semiconductor laser module according to Embodiment 1. [Figure 2C] This is a cross-sectional view at position BB in Figure 2A, showing the configuration of the optical branching substrate of the semiconductor laser module according to Embodiment 1. [Figure 2D] This is a cross-sectional view at position CC of Figure 2A, showing the configuration of the optical branching substrate of the semiconductor laser module according to Embodiment 1. [Figure 3] This is a plan view showing another configuration of the optical branching substrate of the semiconductor laser module according to Embodiment 1. [Figure 4] This is a plan view showing yet another configuration of the optical branching substrate of the semiconductor laser module according to Embodiment 1. [Figure 5] This is a plan view showing yet another configuration of the optical branching substrate of the semiconductor laser module according to Embodiment 1. [Figure 6] This is a plan view showing yet another configuration of the optical branching substrate of the semiconductor laser module according to Embodiment 1. [Figure 7] This is an enlarged perspective view showing an example of the configuration of the laser light incident portion of the optical branching substrate of a semiconductor laser module according to Embodiment 1. [Figure 8] This is an enlarged plan view showing another example of the configuration of the laser light incident portion of the optical branching substrate of a semiconductor laser module according to Embodiment 1. [Figure 9A] This is an enlarged plan view showing yet another example of the configuration of the laser light incident portion of the optical branching substrate of a semiconductor laser module according to Embodiment 1. [Figure 9B] This is a schematic diagram showing the coupling of laser light, based on a cross-sectional view of the optical branching substrate of the semiconductor laser module according to Embodiment 1 at position AA in Figure 9A. [Figure 9C] This is a schematic diagram, shown in an enlarged cross-sectional view, illustrating how a diffraction grating structure is used to couple the output light into an optical fiber at the output portion of the optical branching substrate of a semiconductor laser module according to Embodiment 1. [Figure 10A] It is a schematic perspective view showing another configuration of the semiconductor laser module according to Embodiment 1. [Figure 10B] It is a schematic diagram showing the state of laser light coupling by a cross-sectional view including the optical axis of the semiconductor laser element in FIG. 10A of the semiconductor laser module according to Embodiment 1. [Figure 10C] It is a schematic diagram showing the state of laser light coupling by an enlarged cross-sectional view including the active layer of the semiconductor laser element of the semiconductor laser module having the configurations of FIGS. (10A) and (10B) according to Embodiment 1. [Figure 11] It is an enlarged perspective view showing an example of the configuration of the coupling portion of the optical fiber of the optical branching substrate of the semiconductor laser module according to Embodiment 1. [Figure 12] It is a plan view showing another example of the configuration of the output portion of the optical branching substrate of the semiconductor laser module according to Embodiment 1. [Figure 13] It is a schematic perspective view showing the configuration of the semiconductor laser module according to Embodiment 2. [Figure 14] It is a schematic perspective view showing the configuration of the semiconductor laser module according to Embodiment 3. [Figure 15] It is a schematic perspective view showing the configuration of the semiconductor laser module according to Embodiment 4. [Figure 16] It is a diagram showing a schematic configuration of an optical communication device according to Embodiment 5.

Embodiments for Carrying Out the Invention

[0009] Embodiment 1. Figure 1 is a schematic perspective view showing the configuration of a 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 made of a plate-shaped dielectric, and two optical fibers 3a and 3b. The optical branching substrate 2 is positioned between the semiconductor laser element 1 and the optical fibers 3a and 3b. In the semiconductor laser module 100, the laser light 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 at the branching section 22. The laser light 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 2, but can be 2 or more.

[0010] The semiconductor laser element 1 is a device that generates laser oscillation when an electric current is applied. In other words, the semiconductor laser element 1 is an element that outputs laser light. Various laser structures such as distributed feedback lasers, external cavity lasers, photonic crystal lasers, and photonic crystal surface-emitting lasers can be used as the semiconductor laser element 1. The optical branching substrate 2 is configured such that the laser light damage threshold is higher than that of the optical fibers 3a and 3b. Therefore, even if the light intensity of the laser light output from the semiconductor laser element 1 is higher than the damage threshold of the optical fiber 3a or optical fiber 3b, optical coupling is possible without damaging the optical fibers 3a and 3b by branching the light to below the damage threshold of the optical fiber at the optical branching substrate 2.

[0011] The optical branching substrate 2 is a component that receives laser light output from the semiconductor laser element 1, branches it into multiple waveguides, and optically couples it to multiple optical fibers. Figures 2A to 2D show the detailed configuration of the optical branching substrate 2. Figure 2A is a plan view of the optical branching substrate 2, Figure 2B is a cross-sectional view at position AA in Figure 2A, Figure 2C is a cross-sectional view at position BB in Figure 2A, and Figure 2D is a cross-sectional view at position CC in Figure 2A. As shown in Figure 2A, the optical branching substrate 2 has waveguides formed therein, consisting of an input waveguide 21, a branching section 22, and two output waveguides 23a and 23b branched at the branching section 22. As shown in the cross-sectional views in Figures 2B, 2C, and 2D, the optical branching substrate 2 has a Si-based structure such as SOI (Silicon On Insulator) or SiN. The waveguide of the optical branching substrate 2 is formed within a first dielectric layer 20b, which is formed on the surface of a plate-shaped dielectric substrate 20a made of Si or SiN, and is made of a second dielectric material with a refractive index higher than that of the first dielectric layer 20b.

[0012] Around the waveguides of the optical branching substrate 2 (input waveguide 21 in Figures 2B and 2C, and output waveguides 23a and 23b in Figure 2D), a first dielectric layer 20b, which serves as a cladding layer, is provided, for example, an SiO2 layer (refractive index approximately 1.45 at a wavelength of 1310 nm). The waveguide is formed of a second dielectric material with a higher refractive index than the cladding layer, surrounded by this cladding layer. As the second dielectric material, Si (refractive index approximately 3.50 at a wavelength of 1310 nm) or SiN (refractive index approximately 1.99 at a wavelength of 1310 nm) is used. Due to the difference in refractive index between the second dielectric material constituting the waveguide and the SiO2 layer that serves as the cladding layer, small waveguide dimensions can be used, for example, 220 nm high × 500 nm wide for Si waveguides, and 400 nm wide × 1000 nm wide for SiN waveguides. Similarly, branching sections such as MMI couplers, directional couplers, and curved waveguides can also be miniaturized. Therefore, by using the optical branching substrate 2 to branch the laser light output from the semiconductor laser element 1, it becomes possible to miniaturize the optical branching section compared to the case where a conventional spatial optical system is used. When a conventional spatial optical system is used to branch the laser light from the semiconductor laser element 1, it is difficult to mount it in the housing of a semiconductor laser module (for example, QSFP-DD (length 36 mm) or OSFP (length 75.5 mm)) which is being considered for use in co-packaged optics. However, as shown in this application, by using the optical branching substrate 2 to branch the laser light from the semiconductor laser element 1, it becomes possible to mount it in the housing of a semiconductor laser module.

[0013] Figure 2A shows a configuration in which one input waveguide 21 branches into two output waveguides 23a and 23b at a branching section 22 composed of Y-branch waveguides. The configuration of branching into multiple output waveguides, i.e., the branching section, is not limited to the configuration shown in Figure 2A, but can also be a 1×2 MMI (MultiMode Interference) coupler shown as branching section 22a in Figure 3, a directional coupler shown as branching section 22b in Figure 4, etc. When the number of branches is 3 or more, i.e., the number of output waveguides is 3 or more, the branching section can be configured to branch into 3 or more output waveguides 23 using multiple Y-branch waveguides, as shown as branching section 22c in Figure 5, or to branch into N output waveguides 23 using a 1×N MMI coupler, as shown as branching section 22d in Figure 6. Of course, the Y-branch waveguide 22 in Figure 2A, the 1x2 MMI coupler 22a in Figure 3, or the 1xN MMI coupler 22d in Figure 6, or the directional coupler 22b in Figure 4 may be combined to configure branching into three or more output waveguides. It is desirable to select the number of branches to be the minimum number of divisions at which the optical intensity falls below the optical fiber damage threshold, but when using a fiber connector composed of multiple optical fibers, such as an MPO (Multi-fiber Push On) connector, the number of branches may be set according to the number of optical fibers.

[0014] Furthermore, the advantage of receiving laser light from the semiconductor laser element 1 in the optical branching substrate 2 instead of an optical fiber lies in the design flexibility of the waveguide. For example, in a single-mode fiber, the mode field diameter is a fixed value of 9.2 μm at a wavelength of 1310 nm, whereas in the waveguide formed in the optical branching substrate 2, the mode field diameter can be adjusted by appropriately designing the waveguide structure. For example, the mode field diameter can be adjusted by providing a spot size converter 31 that changes the width and height of the waveguide toward the incident end face 34 of the optical branching substrate 2, as shown in Figure 7, or by providing a window structure 32 in which there is no waveguide near the incident end face 34, as shown in Figure 8. By appropriately adjusting the mode field diameter through the design of the optical branching substrate 2, the light density at the incident end face of the optical branching substrate 2 can be reduced compared to an optical fiber, making it possible to couple light of a higher intensity than the damage threshold of an optical fiber.

[0015] Similarly, the mode field diameter can be adjusted at the exit end face by providing the spot size converter 31 shown in Figure 7 or the window structure 32 shown in Figure 8. By bringing the mode field diameter at the exit end face closer to the mode field diameter of the optical fiber, the coupling efficiency between the output waveguide and the optical fiber can be improved.

[0016] Furthermore, to optically couple the semiconductor laser element 1 and the optical branching substrate 2, a diffraction grating structure 41 may be formed on the optical branching substrate 2, as shown in Figure 9A and Figure 9B, a cross-sectional view at position AA in Figure 9A. The incident laser light from the semiconductor laser element 1 is coupled to the diffraction grating structure 41 and propagated to the input waveguide 21. In this case, since the laser light is incident from the top surface of the optical branching substrate 2, the laser module can be miniaturized compared to the case where the laser light is incident from the end face of the optical branching substrate 2. As shown in Figure 9C, the coupling of laser light by the diffraction grating structure 41 can also be used in the part where the output light of the optical branching substrate 2 is coupled to the fiber 3.

[0017] Furthermore, in order to optically couple the semiconductor laser element 1 and the optical branching substrate 2, the semiconductor laser element 1 may be placed on the optical branching substrate 2, and the laser light output by the semiconductor laser element 1 and the input waveguide 21 may be optically coupled using evanescent light seeping from the active layer 11 of the semiconductor laser element 1. This configuration is shown in the perspective view of Figure 10A, the schematic diagram of a cross-sectional view including the optical axis of the laser light of the semiconductor laser element 1 in Figure 10B, and the schematic diagram of a cross-sectional view including the active layer 11 of the semiconductor laser element 1 in Figure 10C. With this configuration, compared to the case where light is incident from the end face of the optical branching substrate 2 and the case where a diffraction grating structure 41 is formed on the optical branching substrate 2 for coupling, it is possible to improve the coupling efficiency between the semiconductor laser element 1 and the optical branching substrate 2 and to miniaturize the semiconductor laser module.

[0018] The optical fiber is a component that receives laser light output from the output waveguide of the optical branching substrate 2 and guides the light to the PIC. The optical fiber is positioned in accordance with the location of the output waveguide of the optical branching substrate 2. To simplify the mounting of the optical fiber, a groove 25 shown in Figure 11 may be provided on the output end face of the optical branching substrate 2. As shown in Figure 11, mounting can be simplified by placing the optical fiber 3 in the groove 25.

[0019] It is not necessary to provide the same number of optical fibers as the output waveguides of the optical branching substrate 2. A portion of the output waveguides of the optical branching substrate 2 may be used as an output for monitoring the output of the semiconductor laser element 1, or as an output for monitoring the wavelength. In this case, for example, as shown in Figure 12, a directional coupler may be used to extract light of a weaker intensity than that of output waveguide 23a from output waveguide 23a coupled to the optical fiber and use it as an output for monitoring the output, or as an output for monitoring the wavelength.

[0020] Embodiment 2. Figure 13 is a schematic diagram of a 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 positioned 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 section 22, and output waveguides 23a and 23b branched at the branching section 22, is positioned 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 focused by the focusing lens 4 and then optically coupled to the input waveguide 21. At the branching section 22, it is branched into two output waveguides 23a and 23b, and then 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 as described in Embodiment 1 can be used, and it goes without saying that the number of output waveguides is not limited to 2, but can be 2 or more.

[0021] The focusing lens 4 is a component that focuses the laser light from the semiconductor laser element 1 and reduces its 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 accordingly, the coupling efficiency between the semiconductor laser element 1 and the optical branching substrate 2 can be improved.

[0022] Embodiment 3. Figure 14 is a schematic diagram of a semiconductor laser module 700 according to Embodiment 3. The semiconductor laser module 700 includes 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 consisting of a branching section 221 following the input waveguide 211 and output waveguides 23a1 and 23b1 branched at the branching section 221, and a second branching unit 2a2 consisting of a branching section 222 following the input waveguide 212 and output waveguides 23a2 and 23b2 branched at the branching section 222. Laser light from the semiconductor laser element 1a is coupled to the input waveguide 211, laser light output from the output waveguide 23a1 is optically coupled to the optical fiber 3a1, and laser light output from the output waveguide 23b1 is optically coupled to the optical fiber 3b1. Similarly, the laser light from the semiconductor laser element 1b is coupled to the input waveguide 212, the laser light output from the output waveguide 23a2 is optically coupled to the optical fiber 3a2, and the laser light output from the output waveguide 23b2 is optically coupled to the optical fiber 3b2. Figure 14 shows an example in which one input waveguide is branched into two output waveguides in the first branching unit 2a1 and the second branching unit 2a2, but it goes without saying that the number of output waveguides is not limited to two, and a configuration with three or more branches is also possible. In addition, in Figure 14, the first branching unit 2a1 and the second branching unit 2a2 are provided on a single optical branching substrate 2a, but they may be provided on separate optical branching substrates. In this case, the branching configuration of each optical branching substrate, or the configuration of the incident end face and the exit end face, does not need to be the same.

[0023] The semiconductor laser module 700 according to this third embodiment can increase the total amount of light intensity output from the semiconductor laser module 700 by comprising two or more semiconductor laser elements.

[0024] Embodiment 4. Figure 15 is a schematic diagram of a 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 positioned between the semiconductor laser element 1c and the optical fibers. The optical branching substrate 2a in the semiconductor laser module 800 has a configuration similar to the optical branching substrate 2a described in Embodiment 3, comprising 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 is branched to two output waveguides 23a1, 23b1, and output waveguides 23a2, 23b2, respectively. The laser beams output from each output waveguide are optically coupled to optical fibers 3a1, 3b1, 3a2, and 3b2, respectively. Figure 15 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, i.e., multiple laser beams. The number of input waveguides in the optical branching substrate, i.e., the number of branching units, should be set according to the number of laser beams output. Figure 15 shows an example in which one input waveguide is branched into two output waveguides in the first branching unit 2a1 and the second branching unit 2a2, but it goes without saying that the output waveguides are not limited to two; they can be branched into three or more. Also, in Figure 15, the first branching unit 2a1 and the second branching unit 2a2 are provided on a single optical branching substrate 2a, but they can be provided on separate optical branching substrates. In this case, the branching configuration of each optical branching substrate, or the configuration of the incident end face and the exit end face, does not need to be the same.

[0025] According to this embodiment 5, the semiconductor laser module can be equipped with two or more semiconductor laser elements 1c that output laser beams, thereby increasing the total amount of light intensity output from the semiconductor laser module.

[0026] Embodiment 5. Figure 16 is a schematic diagram of the optical communication device 900 according to Embodiment 5. The optical communication device 900 includes one of the semiconductor laser modules described in Embodiments 1 to 4 as the semiconductor laser module 91 in Figure 16. In Figure 16, only the semiconductor laser module 91 and optical fiber 92, as well as the PIC 94, ASIC 95, and electronic circuit 96 connecting the PIC 94 and ASIC 95 in the Co-packaged chip 93 are shown, but other components necessary for an optical communication device may also be included. In the optical communication device 900, light is propagated from the semiconductor laser module 91 to the PIC 94 through multiple optical fibers 92. Conventionally, the total amount of light intensity propagated from one semiconductor laser module to the PIC was limited by the damage threshold of the optical fiber, but with the configuration of this embodiment, it is possible to propagate light intensity exceeding the damage threshold of the optical fiber to the PIC. Furthermore, by using the semiconductor laser module 91, even when the light is split within the semiconductor laser module, it becomes possible to mount the semiconductor laser element, optical splitting method (optical splitting substrate), and optical fiber into the housing of the semiconductor laser module (for example, QSFP-DD (length 36 mm), OSFP (length 75.5 mm), etc.) that is being considered for use in co-packaged optics.

[0027] Furthermore, according to the configuration of this embodiment, since the semiconductor laser module 91 and the co-packaged chip 93 are connected by an optical fiber 92, the physical distance between the semiconductor laser module 91 and the co-packaged chip 93 can be increased. Therefore, since the physical distance between the semiconductor laser module 91 and the ASIC 95 can be increased, one of the objectives of conventional co-packaged optics, which is to suppress the degradation of semiconductor laser characteristics due to temperature rise of the ASIC 95 inside the co-packaged chip 93, is also maintained.

[0028] While this application describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but are applicable individually or in various combinations to the embodiments. Accordingly, countless variations not illustrated are envisioned within the scope of the art disclosed herein. For example, these include modifying, adding or omitting at least one component, or extracting at least one component and combining it with a component from another embodiment. [Explanation of symbols]

[0029] 1, 1a, 1b, 1c Semiconductor laser element, 2, 2a Optical branching 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 Groove, 31 Spot size converter, 32 Window structure, 100, 600, 700, 800, 91 Semiconductor laser module, 900 Optical communication device

Claims

1. Semiconductor laser element, an optical branching substrate including an input waveguide to which the laser light output from the semiconductor laser element is coupled, and a branching section that branches the input waveguide into a plurality of output waveguides, the laser light being output from each of the plurality of output waveguides, the optical branching substrate being made of a dielectric; a plurality of optical fibers to which the laser beams output from the plurality of output waveguides are respectively coupled; Equipped with The laser light is coupled to the input waveguide through a window structure.

2. Semiconductor laser element, an optical branching substrate including an input waveguide to which the laser light output from the semiconductor laser element is coupled, and a branching section that branches the input waveguide into a plurality of output waveguides, the laser light being output from each of the plurality of output waveguides, the optical branching substrate being made of a dielectric; a plurality of optical fibers to which the laser beams output from the plurality of output waveguides are respectively coupled; Equipped with a semiconductor laser module having a spot size converter at a portion of the input waveguide to which the laser light is coupled;

3. Semiconductor laser element, an optical branching substrate including an input waveguide to which the laser light output from the semiconductor laser element is coupled, and a branching section that branches the input waveguide into a plurality of output waveguides, the laser light being output from each of the plurality of output waveguides, the optical branching substrate being made of a dielectric; a plurality of optical fibers to which the laser beams output from the plurality of output waveguides are respectively coupled; In addition to providing a semiconductor laser module comprising a diffraction grating structure on an input side of the input waveguide, wherein the laser light output from the semiconductor laser element is coupled to the diffraction grating structure and propagates to the input waveguide.

4. Semiconductor laser element, an optical branching substrate including an input waveguide to which the laser light output from the semiconductor laser element is coupled, and a branching section that branches the input waveguide into a plurality of output waveguides, the laser light being output from each of the plurality of output waveguides, the optical branching substrate being made of a dielectric; a plurality of optical fibers to which the laser beams output from the plurality of output waveguides are respectively coupled; Equipped with The laser light output from the semiconductor laser element has evanescent light, and this evanescent light is coupled to the input waveguide.

5. Semiconductor laser element, an optical branching substrate including an input waveguide to which the laser light output from the semiconductor laser element is coupled, and a branching section that branches the input waveguide into a plurality of output waveguides, the laser light being output from each of the plurality of output waveguides, the optical branching substrate being made of a dielectric; a plurality of optical fibers to which the laser beams output from the plurality of output waveguides are respectively coupled; Equipped with a semiconductor laser module in which grooves are provided at positions on the optical branching substrate where laser light is output from each of the plurality of output waveguides, and each of the plurality of optical fibers is disposed in these grooves.

6. Semiconductor laser element, an optical branching substrate including an input waveguide to which the laser light output from the semiconductor laser element is coupled, and a branching section that branches the input waveguide into a plurality of output waveguides, the laser light being output from each of the plurality of output waveguides, the optical branching substrate being made of a dielectric; a plurality of optical fibers to which the laser beams output from the plurality of output waveguides are respectively coupled; Equipped with A semiconductor laser module, wherein an optical damage threshold of each of the plurality of optical fibers is lower than a maximum light intensity of the laser light output from the semiconductor laser element.

7. 7. The semiconductor laser module according to claim 6, wherein the optical branching substrate includes a dielectric substrate and a first dielectric layer formed on a surface of the dielectric substrate, and each of the input waveguide, the branching portion and the output waveguide is formed inside the first dielectric layer using a second dielectric material having a refractive index higher than a refractive index of the first dielectric layer.

8. The material of the first dielectric layer is SiO 2 8. The semiconductor laser module according to claim 7, wherein the second dielectric material is Si or SiN.

9. 9. An optical communication device comprising the semiconductor laser module according to claim 1.

10. A semiconductor laser element. an optical branching substrate including an input waveguide to which the laser light output from the semiconductor laser element is coupled, and a branching section that branches the input waveguide into a plurality of output waveguides, the laser light being output from each of the plurality of output waveguides, the optical branching substrate being made of a dielectric; a plurality of optical fibers to which the laser beams output from the plurality of output waveguides are respectively coupled; An optical communication device comprising a semiconductor laser module comprising:

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