Semiconductor laser element

Abstract

To provide a semiconductor laser element that offers high output while also being highly resistant to COD. [Solution] A semiconductor laser element comprising a first region and a second region in which a plurality of semiconductor layers are stacked, wherein the first region forms a resonator between a first end face and a mirror region including a diffraction grating, and in a top view, the first region has an optical waveguide comprising a core region extending in the optical axis direction of the resonator and a cladding region sandwiching the core region in a direction perpendicular to the optical axis direction, and the second region is adjacent to the first region in the optical axis direction, and in a top view, the width of the second region in the direction perpendicular to the optical axis direction is greater than the width of the core region in the direction perpendicular to the optical axis direction, and the second region has a second end face from which laser light is emitted.

Description

Technical Field

[0001] The present disclosure relates to a semiconductor laser device.

Background Art

[0002] When realizing a high-power semiconductor laser device, the optical density of the laser light at the end face that emits the laser light is high, which can cause COD (Catastrophic Optical Damage). Various methods have been taken to enhance the resistance to COD.

[0003] For example, as an example of a semiconductor laser device, it includes an optically active region including an optical waveguide, and at least one optically passive region provided at one or more ends of the optical waveguide. At least one of the optically passive regions is wider than the optical waveguide, and the light output of the optical waveguide diffracts while crossing at least one optically passive region during use. A semiconductor laser device is disclosed. (Patent Document 1)

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the semiconductor laser device of Patent Document 1, the ratio of the light returning from the end face to the optically active region is low. Therefore, it is difficult to achieve efficient resonance in the semiconductor laser device of Patent Document 1, and it is difficult to obtain high-power laser light.

[0006] An embodiment of the present disclosure aims to provide a semiconductor laser device with high resistance to COD while increasing the output.

Means for Solving the Problems

[0007] One embodiment is a semiconductor laser element comprising a first region and a second region in which a plurality of semiconductor layers are stacked, wherein the first region forms a resonator between a first end face and a mirror region including a diffraction grating, and in a top view, the first region has an optical waveguide including a core region extending in the optical axis direction of the resonator and a cladding region sandwiching the core region in a direction perpendicular to the optical axis direction, and the second region is adjacent to the first region in the optical axis direction, and in a top view, the width of the second region in the direction perpendicular to the optical axis direction is greater than the width of the core region in the direction perpendicular to the optical axis direction, and the second region has a second end face from which laser light is emitted.

[0008] One embodiment is a semiconductor laser element having a plurality of semiconductor layers stacked together, comprising a channel waveguide which is a first region and a slab waveguide which is a second region adjacent to the channel waveguide in the optical axis direction, wherein the channel waveguide has a resonator formed between a first end face and a diffraction grating, and the slab waveguide has a second end face on the opposite side of the first end face via the diffraction grating from which laser light can be emitted.

[0009] One embodiment is a semiconductor laser element including a laminate in which a plurality of semiconductor layers are stacked, The laminated body is The first end face and, A second end face facing the first end face, from which laser light is emitted, The first region located on the first end face side, A second region located on the second end face side, Includes, The first region is, An optical waveguide comprising: a core region extending along a first direction from the first end face toward the second end face; and a plurality of cladding regions arranged on both sides of the core region in a second direction perpendicular to both the first direction and the stacking direction of the laminate; A diffraction grating provided in at least a portion of the first region, Includes, The semiconductor laser element has a width greater than the width of the core region.

Effect of the Invention

[0010] According to one embodiment of the present disclosure, a semiconductor laser device with high resistance to COD while increasing the output can be provided.

Brief Description of the Drawings

[0011] [Figure 1] It is a schematic top view showing the semiconductor laser device of Embodiment 1. [Figure 2] It is a schematic cross-sectional view showing a cross-section along line II-II of FIG. 1. [Figure 3] It is a schematic cross-sectional view showing a cross-section along line III-III of FIG. 1. [Figure 4] It is a schematic cross-sectional view showing a cross-section along line IV-IV of FIG. 1. [Figure 5] It is a schematic top view showing Modification 1 of the semiconductor laser device of Embodiment 1. [Figure 6] It is a schematic top view showing Modification 2 of the semiconductor laser device of Embodiment 1. [Figure 7] It is a schematic top view showing Modification 3 of the semiconductor laser device of Embodiment 1. [Figure 8] It is a schematic cross-sectional view showing the cross-section of the semiconductor laser device of Embodiment 2. [Figure 9] It is a schematic top view showing the semiconductor laser device of Embodiment 3. [Figure 10] It is a schematic cross-sectional view showing a cross-section along line X-X of FIG. 9. [Figure 11] It is a schematic cross-sectional view showing the semiconductor laser device of Embodiment 4. [Figure 12] It is a schematic top view showing the semiconductor laser device of Embodiment 5. [Figure 13] It is a schematic top view showing the semiconductor laser device of Embodiment 6.

Modes for Carrying Out the Invention

[0012] A semiconductor laser element according to an embodiment of the present invention is a semiconductor laser element comprising a laminate in which a plurality of semiconductor layers are stacked, wherein the laminate includes a first end face, a second end face facing the first end face and emitting laser light, a first region disposed on the side of the first end face, and a second region disposed on the side of the second end face. Includes, The first region includes an optical waveguide comprising a core region extending along a first direction from the first end face toward the second end face, and a plurality of cladding regions arranged on both sides of the core region in a second direction perpendicular to both the first direction and the stacking direction of the laminate, and a diffraction grating provided in at least a portion of the first region, Includes, The semiconductor laser element has a width greater than the width of the core region.

[0013] The embodiments of the present invention will be described in detail below. However, the embodiments shown below are illustrative examples of semiconductor laser elements and methods for manufacturing the same that embody the technical concept of the present invention, and the present invention is not limited to the semiconductor laser elements and methods for manufacturing the same shown below.

[0014] (Embodiment 1) First, an overview of the semiconductor laser element L1 of Embodiment 1 will be described using Figures 1 and 2. Figure 1 is a schematic top view representing the semiconductor laser element L1 of Embodiment 1. Figure 2 is a schematic cross-sectional view showing a cross-section along the line II-II in Figure 1.

[0015] <Semiconductor laser element L1> The semiconductor laser element L1 of Embodiment 1 is a laser element including a distributed Bragg reflector (DBR) and has the following configuration. The semiconductor laser element L1 includes a first region 10 and a second region 20 in which a plurality of semiconductor layers are stacked, wherein the first region 10 forms a resonator 12 between a first end face E1 and a mirror region 14 including a diffraction grating 50, and in a top view, the first region 10 has an optical waveguide including a core region 11 extending in the optical axis direction of the resonator 12 and cladding regions 16 and 18 sandwiching the core region 11, and the second region 20 is adjacent to the first region 10 in the optical axis direction, and in a top view, the width of the second region 20 in the direction perpendicular to the optical axis direction is greater than the width of the core region 11 in the direction perpendicular to the optical axis direction, and the second region 20 has a second end face E2 from which laser light LB is emitted.

[0016] This makes it possible to provide a semiconductor laser element that offers high output while also being highly resistant to COD.

[0017] In this specification, the stacking direction of multiple semiconductor layers may be referred to as the x-direction, the optical axis direction of the resonator (the same as the optical axis direction of the optical waveguide and the extension direction of the core region) may be referred to as the z-direction or first direction, and the direction perpendicular to both the x-direction and the z-direction may be referred to as the transverse direction, y-direction, or second direction. The dimension measured along the z-direction is referred to as "length," and the dimension measured along the y-direction is referred to as "width."

[0018] The semiconductor laser element L1 includes a laminate in which a plurality of semiconductor layers are stacked in the x direction. The semiconductor laser element L1 has a first conductive semiconductor layer 310, a second conductive semiconductor layer 330, and an active layer 320 disposed between the first conductive semiconductor layer 310 and the second conductive semiconductor layer 330. The semiconductor laser element L1 has a first region 10 and a second region 20, and further has a first end face E1 on the first region 10 side and a second end face E2 on the second region 20 side. The first end face E1 is a surface that reflects light generated in the laminate, and the second end face E2 is an end face from which laser light LB is emitted. The first end face E1 and the second end face E2 are arranged opposite each other.

[0019] (1st area 10) The first region 10 has a first end face E1 and a mirror region 14. The mirror region 14 is the region containing the diffraction grating 50. In a top view, the extent of the mirror region 14 coincides with the extent in which the diffraction grating 50 is formed. In a cross-sectional view, the mirror region 14 consists of the region in which the diffraction grating 50 is formed and the region directly below it. In Figure 2, the region between the two dashed lines indicating both ends of the diffraction grating 50 in the z direction is the mirror region 14. Since the diffraction grating 50 is designed to reflect light of a predetermined wavelength, a resonator 12 is formed between the first end face E1 and the mirror region 14. The effective reflective edge of the diffraction grating 50 can be considered to be located within the diffraction grating 50 (i.e., within the mirror region 14). However, in this specification, for simplicity, as shown in Figure 2, the end on the first end E1 side of the diffraction grating 50 is shown as the reflective edge of the diffraction grating 50 and the resonator 12 is illustrated. The same applies to the following figures (except for Figure 10). In a top view, the first region 10 includes a core region 11 extending in the optical axis direction (z direction) of the resonator 12, and two cladding regions 16 and 18 located on either side of the core region 11 in the lateral direction (y direction), sandwiching the core region 11. The core region 11 and the cladding regions 16 and 18 constitute an optical waveguide. When the optical waveguide is a refractive index waveguide, the core region 11 is a region with a relatively higher equivalent refractive index than the cladding regions 16 and 18, and in a semiconductor laser element with a ridge formed, it is the region directly below the ridge region. When the optical waveguide is a gain waveguide, the core region 11 is the region directly below the first electrode 44 formed in a stripe shape on the semiconductor laser element.

[0020] In the first region 10, light is confined in the stacking direction (x direction) by multiple semiconductor layers and confined in the transverse direction (y direction) by cladding regions 16 and 18. Therefore, the first region 10 can be considered as a channel waveguide. The light is guided in the optical axis direction (z direction) of the resonator 12.

[0021] (Second area 20) The second region 20 is located adjacent to the first region 10 in the optical axis direction of the resonator 12. In Figure 1, the second region 20 is in contact with the first region 10. In a top view, the width of the second region 20 in the lateral direction (y direction) is greater than the width of the core region 11 of the first region 10 in the lateral direction (y direction). The second region 20 has a second end face E2 from which the laser beam LB is emitted.

[0022] In the second region 20, light is confined in the stacking direction (x-direction) by multiple semiconductor layers. The second region 20 either does not have a configuration corresponding to the core region 11 and cladding regions 16 and 18 of the first region 10, or it has a core region with a sufficiently wide width in the lateral direction (y-direction). Also, the width of the second region 20 is larger than the width of the laser beam LB. Therefore, in the second region 20, the laser beam LB is not confined in the lateral direction (y-direction). Alternatively, the lateral optical confinement in the second region 20 is weaker than that in the first region 10. Consequently, the laser beam LB entering the second region 20 from the first region 10 guides while spreading in the lateral direction (y-direction). In other words, in the second region 20, the width of the laser beam spreads in the lateral direction (y-direction). In this specification, the width of the laser beam LB is defined as D4σ. D4σ is four times the width of the standard deviation σ of the intensity distribution in the stacking direction (x-direction) or the lateral direction (y-direction). D4σ is defined in the ISO international standard.

[0023] The second region 20 is preferably a slab waveguide. When the second region 20 is a slab waveguide, the light is not substantially confined laterally and tends to spread laterally. The optical density of the laser beam LB at the second end face E2 can be further reduced, improving resistance to COD. The light is guided in the direction of the optical axis of the resonator 12.

[0024] Next, the operation of the semiconductor laser element L1 of Embodiment 1 will be described using Figure 1. In Figure 1, the dashed line represents the spread of the laser beam LB. The semiconductor laser element L1 has a semiconductor laminate 30 formed by stacking semiconductor layers, and has a first region 10 and a second region 20. In the first region 10, light can be confined in the stacking direction (x direction) and the lateral direction (y direction) by an optical waveguide. In addition, in the first region 10, the light confined by the optical waveguide can be resonated in a resonator 12 formed by the first end face E1 and the mirror region 14 (more precisely, the diffraction grating 50 included in the mirror region 14), thereby efficiently amplifying the light. The second region 20 guides the laser beam LB amplified in the first region 10. Since the lateral width of the second region 20 is greater than the width of the core region 11 of the first region 10, the width of the laser beam LB can be widened in the second region 20. This reduces the optical density of the laser beam LB at the second end face E2, thereby improving resistance to COD. Therefore, the semiconductor laser element L1 of Embodiment 1 can increase optical output while also improving resistance to COD.

[0025] In a top view, the width of the second end face E2 in the direction perpendicular to the optical axis direction (z direction) (y direction, i.e., the transverse direction) is preferably greater than the width of the laser beam LB at the second end face E2, and the width of the second region 20 in the direction perpendicular to the optical axis direction (z direction) (y direction, i.e., the transverse direction) is preferably constant in the optical axis direction. As a result, the width of the second region 20 is always greater than the width of the laser beam LB guiding within the second region 20. Therefore, the laser beam LB can spread freely in the transverse direction (y direction), which reduces the optical density of the laser beam LB at the second end face E2 and improves resistance to COD.

[0026] The length of the first region 10 in the optical axis direction (z direction) may be, for example, 1000 μm or more and 10000 μm or less, preferably 2000 μm or more and 6000 μm or less. When the length of the diffraction grating 50 is constant, by relatively increasing the length of the first region 10, the resonator length becomes relatively longer, and light can be amplified efficiently.

[0027] The length of the second region 20 in the optical axis direction (z direction) may be, for example, 0.01 to 0.35 times, preferably 0.01 to 0.1 times, the length of the first region in the optical axis direction (z direction). This makes the length of the second region 20, which does not contribute to oscillation, shorter than that of the first region 10, thus preventing a decrease in luminous efficiency. The width of the second region 20 in the lateral direction (y direction) may be 1.5 to 100 times, preferably 2 to 100 times, the width of the core region of the first region 10. This allows the laser beam LB to spread sufficiently in the lateral direction within the second region 20, thus reducing the optical density of the laser beam LB at the second end face E2. Consequently, resistance to COD is improved.

[0028] Up to this point, we have described the general outline of the semiconductor laser element L1 of Embodiment 1. Below, we will describe each component constituting the semiconductor laser element L1 using Figures 2, 3, and 4. Figure 2 is a schematic cross-sectional view showing a cross-section along line II-II in Figure 1. Figure 3 is a schematic cross-sectional view showing a cross-section along line III-III in Figure 1. Figure 4 is a schematic cross-sectional view showing a cross-section along line IV-IV in Figure 1.

[0029] (Circuit board 300) The substrate 300 supports the semiconductor laminate 30. The substrate 300 may be a growth substrate for the semiconductor laminate 30. The substrate 300 may be a GaN substrate, a GaAs substrate, or an InP substrate, etc. The substrate 300 may contain an impurity of a first conductivity type. The first conductivity type may be n-type. The impurity may be, for example, silicon or germanium.

[0030] (Semiconductor laminate 30) The semiconductor laminate 30 is placed on a substrate 300. The semiconductor laminate 30 has a first conductive semiconductor layer 310, a second conductive semiconductor layer 330, and an active layer 320 disposed between the first conductive semiconductor layer 310 and the second conductive semiconductor layer 330. The first conductive semiconductor layer 310, the second conductive semiconductor layer 330, and the active layer 320 include nitride semiconductors, arsenide semiconductors, or phosphide semiconductors. Preferably, the first conductive semiconductor layer 310, the second conductive semiconductor layer 330, and the active layer 320 are made of nitride semiconductors. Nitride semiconductors have higher COD resistance compared to arsenide semiconductors and phosphide semiconductors, which can further improve the COD resistance of the semiconductor laser element L1. This makes it possible to achieve even higher power output for the semiconductor laser element L1. The semiconductor laminate 30 is formed, for example, by metal-organic vapor deposition.

[0031] (First conductive semiconductor layer 310) The first conductive semiconductor layer 310 is disposed on the substrate 300. The first conductive semiconductor layer 310 has one or more semiconductor layers containing impurities of a first conductivity type. When the first conductive semiconductor layer 310 is an n-side semiconductor layer, the first conductive semiconductor layer 310 may include an n-side cladding layer and an n-side optical guide layer in that order from the substrate 300 side. A crack prevention layer may be provided between the substrate 300 and the n-side cladding layer.

[0032] (active layer 320) The active layer 320 is positioned between the first conductive semiconductor layer 310 and the second conductive semiconductor layer 330. The active layer 320 may be a quantum well having a well layer and a barrier layer. The active layer 320 may be either a single quantum well (one well layer and two barrier layers) or a multiple quantum well (two or more well layers and three or more barrier layers arranged to sandwich each well layer). The wavelength of light emitted from the active layer 320 may be, for example, 360 nm to 2000 nm, preferably 360 nm to 780 nm, and more preferably 360 nm to 570 nm.

[0033] (Second conductive semiconductor layer 330) The second conductive semiconductor layer 330 is disposed on the active layer 320. The second conductive semiconductor layer 330 has one or more semiconductor layers containing impurities of the second conductivity type. When the second conductive semiconductor layer 330 is a p-side semiconductor layer, the second conductive semiconductor layer 330 may include, in order from the active layer 320 side, a p-side optical guide layer, an electron blocking layer, and a p-side contact layer. The p-side optical guide layer may be an undoped semiconductor layer. The electron blocking layer and the p-side contact layer may be p-type semiconductor layers containing p-type impurities. The second conductive semiconductor layer 330 may further include a p-side cladding layer. The p-side cladding layer is not limited to a semiconductor layer and may be a translucent electrode or a protective film.

[0034] (Diffraction grating 50) The mirror region 14 having the diffraction grating 50 functions as a Bragg waveguide. The diffraction grating 50 reflects light of a wavelength that satisfies the Bragg condition. In the semiconductor laser element L1 of Embodiment 1, as shown in Figure 2, the diffraction grating 50 has a periodic structure in which a plurality of protrusions provided in the second conductive semiconductor layer 330 (e.g., the p-side semiconductor layer) and a first medium 52 that fills the recesses between adjacent protrusions are periodically arranged in the optical axis direction (z direction) of the resonator. The protrusions of the second conductive semiconductor layer 330 are the parts that were not etched when forming the plurality of recesses by etching or the like. An example of a method for forming the diffraction grating 50 includes periodically forming a plurality of recesses in the second conductive semiconductor layer 330 by dry etching and forming the first medium 52 in each recess. Dry etching is, for example, reactive ion etching (RIE), and recesses can be formed at predetermined positions in the second conductive semiconductor layer 330 via a mask patterned by electron beam lithography or nanoimprint. The depth of the recess can be controlled by etching conditions (e.g., etching time).

[0035] The lower end of the diffraction grating 50 coincides with the bottom of the recess. If the depths of the multiple recesses are not uniform, the lower end of the diffraction grating 50 is set to the bottom of the deepest recess. The lower end of the diffraction grating 50 may be located midway along the thickness direction of the second conductive semiconductor layer 330. The lower end of the diffraction grating 50 may also be located within the p-side optical guide layer. This brings the diffraction grating 50 closer to the active layer 320, improving the coupling coefficient between the light guiding within the first region 10 and the diffraction grating 50, allowing for more efficient light reflection.

[0036] The oscillation wavelength (Bragg wavelength) is λ B Here, Λ is the period of the diffraction grating 50, q is the order of the diffraction grating, and n is the equivalent refractive index of the mirror region 14 on which the diffraction grating 50 is provided. eq When this is the case, the following relationship (1) is satisfied. λ B ×q = 2 × n eq ×Λ···(1)

[0037] The period Λ of the diffraction grating 50 may be, for example, between 40 nm and 400 nm, between 50 nm and 300 nm, or between 60 nm and 250 nm.

[0038] The reflectance of the diffraction grating 50 at a predetermined wavelength may be 3% or more and 50% or less, preferably 5% or more and 18% or less. The length of the diffraction grating 50 in the periodic direction may be 50 μm or more and 600 μm or less.

[0039] Since the resonator 12 is formed between the mirror region 14 including the diffraction grating 50 and the first end face E1, the position of the diffraction grating 50 can be appropriately set to adjust the resonance conditions. The diffraction grating 50 is provided only in the first region 10, and in a cross-sectional view in the zx plane including the optical axis direction (z direction) and the stacking direction (x direction), it is preferable that the center of the diffraction grating 50 is closer to the second end face E2 than to the first end face E1. This allows for a longer resonator length and efficient amplification of light by resonance.

[0040] The center of the diffraction grating 50 coincides with the midpoint of the distance between the two ends of the diffraction grating 50 in the z direction (the total length of the diffraction grating 50) when viewed in cross-section in the zx plane. One end of the diffraction grating 50 is located on the inner surface on the side of the first end face E1 in the recess closest to the first end face E1, and the other end of the diffraction grating 50 is located on the inner surface on the side of the second end face E2 in the recess closest to the second end face E2.

[0041] Here, the distance from the center of the diffraction grating 50 to the first end face E1 is the sum of the distance from the first end face E1 to the diffraction grating 50 (i.e., to one end of the diffraction grating 50) and half the total length of the diffraction grating 50. Similarly, the distance from the center of the diffraction grating 50 to the second end face E2 is the sum of the distance from the second end face E2 to the diffraction grating 50 (i.e., to the other end of the diffraction grating 50) and half the total length of the diffraction grating 50. Therefore, "the center of the diffraction grating 50 is closer to the second end face E2 than to the first end face E1" is equivalent to "the distance from the second end face E2 to the diffraction grating 50 is shorter than the distance from the first end face E1 to the diffraction grating 50."

[0042] The diffraction grating 50 may be provided only within the range overlapping the core region 11 in a top view, or it may be provided extending from the range overlapping the core region 11 to the range overlapping the cladding regions 16 and 18.

[0043] (First medium 52) The first medium 52 is a material that fills a plurality of recesses formed in the second conductive semiconductor layer 330. The refractive index of the first medium 52 is different from that of the second conductive semiconductor layer 330. This creates a refractive index difference between the first medium 52 and the second conductive semiconductor layer 330, allowing these periodic structures to function as a diffraction grating 50.

[0044] The first medium 52 may be, for example, an oxide, fluoride, or nitride. The material of the first medium 52 may be at least one selected from the group consisting of, for example, indium tin oxide, indium zinc oxide, aluminum oxide, silicon oxide, titanium oxide, magnesium fluoride, barium fluoride, lanthanum fluoride, silicon nitride, aluminum nitride, gallium nitride, aluminum gallium nitride, indium gallium nitride, and silicon oxynitride. By filling the multiple recesses of the second conductive semiconductor layer 330 with the first medium 52, the area of ​​the inner surface of the recesses of the second conductive semiconductor layer 330 that is exposed to air is reduced, and the degradation of the second conductive semiconductor layer 330 is reduced.

[0045] The first medium 52 can be formed by sputtering, atomic layer deposition, vapor deposition, chemical vapor deposition, or sol-gel deposition. The upper surface of the first medium 52 is not necessarily flush with the upper surface of the second conductive semiconductor layer 330; as shown in Figure 2, the upper surface of the first medium 52 may be higher than the upper surface of the second conductive semiconductor layer 330.

[0046] (Ridge 335) As shown in Figure 3, the second conductive semiconductor layer 330 has a ridge 335. The ridge 335 defines the core region 11. The width of the core region 11 substantially coincides with the width of the ridge. The width of the ridge is the width of the lower end of the ridge. Because the semiconductor laser element L1 has a ridge 335, it is easy to confine light laterally by creating a refractive index difference between the core region 11 and the cladding regions 16 and 18. Note that the optical waveguide formed in the first region 10 is not limited to a ridge waveguide, but may be other refractive index waveguides. Also, the optical waveguide may be a gain waveguide. In the case of a gain waveguide, the width of the core region 11 substantially coincides with the stripe width of the first electrode 44.

[0047] (Landscape mode) In the lateral direction, the optical waveguide of the first region 10 may be a single-mode waveguide. In a semiconductor laser element with a single-mode lateral mode, light with good beam quality can be amplified and extracted from the second end face E2 as high-power laser light LB. In this case, the width of the core region 11 of the first region 10 may be, for example, 0.5 μm or more and 5 μm or less, preferably 1 μm or more and 3 μm or less. Note that "light with good beam quality" refers to M 2 This refers to light where the factor is close to 1. For example, M 2 The factor can be between 1 and 1.2.

[0048] In the lateral direction, the optical waveguide of the first region 10 may be a multimode waveguide. A semiconductor laser element equipped with a multimode optical waveguide in the lateral direction can extract even higher-power laser light LB from the second end face E2 compared to a semiconductor laser element equipped with a single-mode waveguide. In this case, the width of the core region 11 of the first region 10 may be, for example, 5 μm or more and 200 μm or less.

[0049] (High-reflectivity coating 72) A high-reflectivity coating 72 is formed on the first end face E1. The reflectivity of the high-reflectivity coating 72 may be, for example, 80% to 99.99% with respect to the oscillation wavelength, preferably 90% to 99.99%. This allows for efficient resonance and amplification of light. The high-reflectivity coating 72 may be a dielectric multilayer film or a metallic reflective film.

[0050] (Anti-reflective coating 74) An anti-reflective coating 74 may be formed on the second end face E2. The reflectivity of the anti-reflective coating 74 may be, for example, 0.01% to 5%, preferably 0.01% to 1%, with respect to the oscillation wavelength. This reduces reflection at the second end face E2, further improving resistance to COD. In addition, by reducing reflection at the second end face E2, reflected light is also reduced, contributing to stable laser oscillation. The anti-reflective coating 74 may be a dielectric multilayer film.

[0051] Next, the configuration of electrodes and other components will be explained using Figures 2, 3, and 4.

[0052] (1st electrode 44) The first electrode 44 is an electrode formed on the upper surface of the second conductive semiconductor layer 330 of the first region 10. The first electrode 44 is in contact with the second conductive semiconductor layer 330 of the first region 10. As shown in Figures 2 and 3, the first electrode 44 is formed on an optical waveguide and is connected to the second conductive semiconductor layer 330 of the core region 11. The first electrode 44 may be, for example, a translucent oxide or a metal. Translucent oxides include, for example, indium tin oxide and indium zinc oxide. Metals include, for example, nickel, gold, rhodium, chromium, tungsten, platinum, titanium, aluminum, and their alloys. The first electrode 44 may be a single layer or a multilayer (i.e., laminate).

[0053] The first electrode 44 may be placed on the second conductive semiconductor layer 330 of the second region 20, in which case an insulating third medium 25 is placed between the first electrode 44 and the second conductive semiconductor layer 330 of the second region 20. Therefore, the second conductive semiconductor layer 330 of the second region 20 is not in contact with the first electrode 44. This reduces unintended current injection into the second region 20.

[0054] (2nd electrode 42) The second electrode 42 is an electrode formed on the substrate 300 side. In the example shown in Figure 2, the second electrode 42 is formed on the back surface of the substrate 300. The second electrode 42 may be, for example, a translucent oxide or a metal. Translucent oxides include, for example, indium tin oxide and indium zinc oxide. Metals include, for example, nickel, gold, rhodium, chromium, tungsten, platinum, titanium, aluminum, and their alloys. The second electrode 42 may be a single layer or a multilayer (i.e., laminate).

[0055] As shown in Figure 3, an insulating layer 60 is formed to protect the side surface of the ridge and the upper surface of the second conductive semiconductor layer 330 on both sides of the ridge. This reduces current injection into unwanted parts of the semiconductor laminate 30 other than directly beneath the ridge. The insulating layer 60 may be, for example, aluminum oxide, silicon oxide, silicon nitride, etc.

[0056] (Second medium 54) The second medium 54 is formed on the upper surface of the diffraction grating 50 within the mirror region 14, specifically on the upper surface of the first medium 52 of the diffraction grating 50. Since it is not necessary for current to flow through the semiconductor laminate 30 within the mirror region 14, the material of the second medium 54 may be conductive or not. The material of the second medium 54 may be a translucent oxide, a metal, air, or an insulator. The material of the second medium 54 may be, for example, indium tin oxide, aluminum oxide, silicon oxide, silicon nitride, gold, platinum, titanium, palladium, or chromium. The second medium 54 may be made of the same material as the first electrode 44.

[0057] (Third medium 25) The third medium 25 is placed on the second conductive semiconductor layer 330 of the second region 20. The third medium 25 is preferably an insulator to prevent unintended current flow to the second region 20. The material of the third medium 25 may be, for example, aluminum oxide, silicon oxide, silicon nitride, tantalum oxide, or niobium oxide.

[0058] The operation of the semiconductor laser element L1 when current is injected into the semiconductor laser element L1 of Embodiment 1 will be described, assuming that the third medium 25 is not an insulator. A first electrode 44 is formed on the semiconductor laminate 30 of the semiconductor laser element L1, extending from the first region 10 to the second region 20. In the first region 10, the first electrode 44 is positioned only on the ridge 335 (i.e., on the core 12), and in the second region 20, it is positioned across the entire upper surface of the semiconductor laminate 30. The semiconductor laser element L1 of Embodiment 1 can be driven by current injection from the first electrode 44. For example, consider the case where current is injected through the first electrode 44 to the first region 10 and the second region 20 with the same current density. In this case, resonance occurs in the first region 10 and laser light LB is generated. In the second region 20, the laser light LB is guided and extracted from the second end face E2. However, because the lateral width of the second region 20 is greater than the lateral width of the core region 11 of the first region 10, it is difficult to uniformly inject current into the entire second region 20 compared to the core region 11. Therefore, when current is injected into the second region 20, temperature and carrier distributions may occur in the lateral direction. Since the refractive index of each semiconductor layer depends on temperature, the temperature distribution that occurs in the second region 20 may also cause refractive index distributions within the second region 20. Furthermore, when current is injected at a large current density, the carrier distribution can also cause refractive index distributions due to free carrier plasma effects and spatial hole burning. These refractive index distributions cause lateral optical confinement in the second region 20, which may prevent the laser light guiding the second region 20 from spreading sufficiently.

[0059] Therefore, in the semiconductor laser element L1 of Embodiment 1, in the first region 10, the first electrode 44 is formed on the second conductive semiconductor layer 330, while in the second region 20, the third medium 25 is formed on the second conductive semiconductor layer 330. By making the third medium 25 an insulator, the current flowing from the first electrode 44 to the second region 20 can be reduced or inhibited. As a result, temperature distributions and carrier distributions are less likely to occur in the second region 20, and lateral light confinement in the second region 20 is less likely to occur, so that the laser beam LB can be spread to the desired size in the second region 20 and then emitted from the second end face E2. Thus, resistance to COD can be improved.

[0060] However, current injection into the second region 20 is permitted as long as it is at or below the transparency current density. At this level, the effect of reducing light absorption in the second region 20 can be obtained, thereby increasing the output of the laser beam LB. Furthermore, at this level, the temperature distribution and carrier distribution described above are less likely to occur, and the beam quality of the laser beam LB guiding the second region 20 is less likely to deteriorate. When current injection is performed at or below the transparency current density, a material with high thermal conductivity may be selected as the third medium 25. The third medium 25 may be, for example, gold, platinum, titanium, palladium, or chromium.

[0061] Of the first region 10, it is not necessary to inject current into the mirror region 14, but it is preferable that the mirror region 14 can be energized. By energizing the mirror region 14, the light absorption in the active layer 320 of the mirror region 14 can be reduced, and the output of the laser beam LB can be increased.

[0062] When the first region 10 is a channel waveguide and the second region 20 is a slab waveguide, the semiconductor laser element L1 of Embodiment 1 can also be described with the following configuration. That is, the semiconductor laser element L1 is a semiconductor laser element L1 in which a plurality of semiconductor layers are stacked, and has a channel waveguide which is the first region and a slab waveguide which is the second region adjacent to the channel waveguide in the optical axis direction of the channel waveguide, the channel waveguide has a resonator 12 consisting of a first end face E1 and a diffraction grating 50, and the slab waveguide has a second end face E2 on the opposite side of the first end face E1 via the diffraction grating 50 from which laser light LB can be emitted.

[0063] In the semiconductor laser element L1, light resonates and is amplified in a channel waveguide containing a diffraction grating 50, and the laser beam LB is spread in a slab waveguide and extracted from the second end face E2. This results in a semiconductor laser element that has high output power and high resistance to COD.

[0064] The channel waveguide, viewed from above, includes a core region extending in the direction of the optical axis of the resonator and a cladding region flanking the core region in a direction perpendicular to the optical axis (y-direction). A ridge waveguide is preferred for the channel waveguide. This facilitates optical confinement in the transverse direction (y-direction). In the transverse direction (y-direction), the channel waveguide may be a single-mode waveguide. In a semiconductor laser element with a single transverse mode, light with good beam quality can be amplified, and a high-power laser beam LB can be extracted from the second end face E2.

[0065] (Variation 1) The semiconductor laser element L2 of Modified Example 1 is a modified version of the semiconductor laser element L1 of Embodiment 1. Figure 5 is a schematic top view representing the semiconductor laser element L2 of Modified Example 1. The semiconductor laser element L2 of Modified Example 1 differs from the semiconductor laser element L1 of Embodiment 1 in that neither end of the mirror region 14 coincides with the boundary B between the first region 10 and the second region 20, and both the end on the first end E1 side and the end on the second end E2 side are located in the first region 10. In other respects, it has the same configuration as the semiconductor laser element L1 of Embodiment 1. "Both ends of the mirror region 14" refers to both ends of the mirror region 14 in a cross-sectional view in the xz plane. In other words, "both ends of the mirror region 14" substantially coincide with "both ends of the diffraction grating 50" described in Embodiment 1.

[0066] Even with this configuration, a semiconductor laser element can be obtained that offers high output while also being highly resistant to COD.

[0067] Furthermore, since the ends of the mirror region 14 do not overlap with the boundary B of the first region 10 and the second region 20, the degree of freedom during the manufacturing of the semiconductor laser element L2 is increased, making it easier to manufacture the semiconductor laser element L2.

[0068] (Modification 2) The semiconductor laser element L3 of Modification 2 is a modification of the semiconductor laser element of Embodiment 1. Figure 6 is a schematic top view representing the semiconductor laser element L3 of Modification 2. In the semiconductor laser element L3 of Modification 2, neither end of the mirror region 14 coincides with the boundary B between the first region 10 and the second region 20. The end on the first end E1 side is located in the first region 10, and the end on the second end E2 side is located in the second region 20. Also, in a cross-sectional view along the zx cross section along the optical axis direction (z direction) and the stacking direction (x direction), the ratio of the length of the diffraction grating 50 placed in the first region 10 to the total length of the diffraction grating 50 in the z direction is greater than 50%. In other respects, it has the same configuration as the semiconductor laser element L1 of Embodiment 1. As will be described later, using "a" and "b" shown in Figure 6, the "total length of the diffraction grating 50 in the x direction" is (a+b), and the "length of the diffraction grating 50 placed in the first region 10" is a.

[0069] Even with this configuration, a semiconductor laser element can be obtained that offers high output while also being highly resistant to COD.

[0070] The mirror region 14 has a first mirror region 14A formed in the first region 10 and a second mirror region 14B formed in the second region 20. The first mirror region 14A and the second mirror region 14B are continuous. When light spreads in the second region 20 and is reflected by the diffraction grating 50 located in the second region 20, the proportion of light fed back to the resonator 12 in the first region 10 decreases. The diffraction grating 50 can be considered as a multilayer mirror incorporated into the semiconductor layer. Each time light passes through a layer constituting the multilayer mirror, the power of the forward wave of light decreases. In the semiconductor laser element L3 of Modified Example 2, in a cross-sectional view along the optical axis, the proportion of the diffraction grating 50 located in the first region 10 to the total diffraction grating 50 is greater than 50%. Therefore, the semiconductor laser element L3 of Modified Example 2 can reflect most of the light with the diffraction grating 50 formed in the first region 10 and feed it back to the resonator 12. Therefore, the semiconductor laser element L3 of Modified Example 2 can efficiently amplify light.

[0071] In Figure 6, in a cross-sectional view along the zx cross-section in the optical axis direction (z direction) and the stacking direction (x direction), let a be the length from the end of the mirror region 14 located in the first region 10 (the end on the first end E1 side) to the boundary B between the first region 10 and the second region 20 (i.e., the length of the first mirror region 14A), and let b be the length from the boundary B between the first region 10 and the second region 20 to the end of the mirror region 14 located in the second region 20 (the end on the second end E2 side) (i.e., the length of the second mirror region 14B). Then a / (a+b)×100(%) may be 50% or more and less than 100%, preferably 75% or more and less than 100%, and more preferably 90% or more and less than 100%.

[0072] Furthermore, since none of the edges of the mirror region 14 coincide with the boundary B between the first region 10 and the second region 20, the degree of freedom during the manufacturing of the semiconductor laser element L2 is increased, making it easier to manufacture the semiconductor laser element L3.

[0073] (Variation 3) Figure 7 is a schematic top view representing the semiconductor laser element L4 of Modified Example 3. The semiconductor laser element L4 of Modified Example 3 differs from the semiconductor laser element L1 of Embodiment 1 in that the optical axis X2 of the resonator 12 is tilted by an angle θ with respect to the normal X1 of the second end face E2. Other aspects are the same as the semiconductor laser element L1 of Embodiment 1.

[0074] Even with this configuration, a semiconductor laser element can be obtained that offers high output while also being highly resistant to COD.

[0075] Furthermore, because the optical axis X2 is tilted with respect to the normal X1, the amount of light reflected back to the resonator 12, which is reflected by the second end face E2 or by optical components used together with the semiconductor laser element L4, is further reduced, thus further improving resistance to reflected light. The angle θ may be, for example, between 0.01° and 10°.

[0076] The periodic direction of the diffraction grating 50 formed in the mirror region 14 coincides with the direction (z-direction) of the optical axis X2 of the resonator 12. Since the boundary B between the first region 10 and the second region 20 is formed perpendicular to the optical axis X2 of the resonator 12, the boundary B between the first region 10 and the second region 20 is also tilted by an angle θ with respect to the second end face E2 in accordance with the tilt of the optical axis X2 of the resonator 12.

[0077] (Embodiment 2) Figure 8 is a schematic cross-sectional view showing a cross-section of the semiconductor laser element L5 of Embodiment 2. The semiconductor laser element L5 of Embodiment 2 differs from the semiconductor laser element L1 of Embodiment 1 in that the diffraction grating 50 is formed in the first conductive semiconductor layer 310 of the first region 10. Other aspects are the same.

[0078] Even with this configuration, a semiconductor laser element can be obtained that offers high output while also being highly resistant to COD.

[0079] When the first conductive semiconductor layer 310 is an n-side semiconductor layer, the first conductive semiconductor layer 310 may include an n-side cladding layer 314 and an n-side optical guide layer 312 in that order from the substrate 300 side. In the example shown in Figure 8, the diffraction grating 50 is formed by a plurality of protrusions provided on the upper surface side of the n-side cladding layer 314 and a plurality of protrusions provided on the lower surface side of the n-side optical guide layer 312, which are arranged periodically in the optical axis direction (x direction). However, the position of forming the diffraction grating 50 is not limited to the form shown in Figure 8. For example, the n-side cladding layer 314 may be a multilayer structure of two or more layers, and the diffraction grating 50 may be formed by the first n-side cladding layer and the second n-side cladding layer. Similarly, the n-side optical guide layer 312 may be a multilayer structure of two or more layers, and the diffraction grating 50 may be formed by the first n-side optical guide layer and the second n-side optical guide layer. Furthermore, the diffraction grating 50 is not limited to a periodic structure of protrusions provided on adjacent surfaces of two types of semiconductor layers. For example, in Figure 8, the recesses of the n-side cladding layer 314 (the portions between adjacent protrusions) are filled with the protrusions of the n-side optical guide layer 312, but these recesses may be filled with a medium having a refractive index different from that of the first conductive semiconductor layer 310.

[0080] (Embodiment 3) Figure 9 is a schematic top view representing the semiconductor laser element L6 of Embodiment 3. Figure 10 is a schematic cross-sectional view showing a cross-section along line XX in Figure 9. The semiconductor laser element L6 of Embodiment 3 is a distributed feedback (DFB) laser element and differs from the semiconductor laser element L1 of Embodiment 1 in the following respects. That is, as shown in Figures 9 and 10, the semiconductor laser element L6 of Embodiment 3 has a ridge 335 in the first region 10, and the diffraction grating 50 is provided only in the first region 10, and in a top view, the diffraction grating 50 is present in all regions where the ridge 335 is provided. In other respects, it is the same as the semiconductor laser element L1 of Embodiment 1.

[0081] Even with this configuration, a semiconductor laser element can be obtained that offers high output while also being highly resistant to COD.

[0082] The semiconductor laser element L6 operates as a distributed feedback laser element, enabling laser oscillation in a single longitudinal mode, or a state close to a single longitudinal mode.

[0083] In Figure 10, the diffraction grating 50 is provided only within the second conductive semiconductor layer 330, between the boundary B between the first region 10 and the second region 20 and the first end face E1. The diffraction grating 50 may also be provided at another location, for example, only within the first conductive semiconductor layer 310. Furthermore, in the top view shown in Figure 9, the diffraction grating 50 may be provided only in the core region 11, or it may be provided across the core region 11 and the cladding regions 16 and 18.

[0084] The ridge width of the semiconductor laser element L6 is preferably determined such that the transverse mode satisfies the single-mode condition. This results in a single transverse-mode semiconductor laser element, enabling laser oscillation in a single longitudinal mode. The ridge width may be, for example, 0.5 μm or more and 5 μm or less.

[0085] The semiconductor laser element L6 may have a phase shift structure PS. A 1 / 4 wavelength phase shift is preferred for the phase shift structure PS. This allows for easy single-longitudinal mode conversion and laser oscillation. When the phase shift structure PS is provided, an anti-reflective coating 74 is provided on the first end face E1 and the second end face E2. Note that the phase shift structure PS is not mandatory. When the phase shift structure PS is not provided, a high-reflectivity coating 72 is provided on the second end face E2.

[0086] (Embodiment 4) Figure 11 is a schematic cross-sectional view showing the semiconductor laser element L7 of Embodiment 4. The semiconductor laser element L7 of Embodiment 4 differs from the semiconductor laser element L1 of Embodiment 1 in the following respects. That is, as shown in Figure 11, the semiconductor laser element L7 of Embodiment 4 is a semiconductor laser element L7 having a window structure 80 in the second region 20, and the end of the mirror region 14 is not included in the window structure 80. In other words, the window structure 80 is formed so as not to overlap with the mirror region 14, and the end of the mirror region 14 (the end on the second end face E2 side) is not located within the window structure 80. Other respects are the same as the semiconductor laser element L1 of Embodiment 1.

[0087] Even with this configuration, a semiconductor laser element can be obtained that offers high output while also being highly resistant to COD.

[0088] The semiconductor laser element L7 of Embodiment 4 oscillates in the red or infrared range. The semiconductor laser element L7 includes an arsenide semiconductor or phosphide semiconductor formed on a GaAs substrate or an InP substrate. In this specification, red light means light with a peak wavelength in the range of 600 nm or more and less than 780 nm. Infrared light means light with a peak wavelength in the range of 780 nm or more and 2000 nm or less.

[0089] The window structure 80 is a region where Zn or group III vacancies are diffused, and it has a larger band gap energy than the active layer 320 of the first region 10. Therefore, the boundary of the window structure 80 in a top view can be identified by performing microscopic photoluminescence measurements along the optical axis and examining the presence or absence of light absorption at each position.

[0090] (Embodiment 5) Figure 12 is a schematic top view representing the semiconductor laser element L8 of Embodiment 5. The semiconductor laser element L8 of Embodiment 5 differs from the semiconductor laser element L1 of Embodiment 1 in the following respects. That is, as shown in Figure 12, the semiconductor laser element L8 of Embodiment 5 has a convex lens surface E2R on a part of its second end face E2. In other words, the semiconductor laser element L8 has a lens surface E2R on its second end face E2. The laser beam LB can pass through the lens surface E2R. Other respects are the same as the semiconductor laser element L1 of Embodiment 1.

[0091] Even in this configuration, a semiconductor laser element can be obtained that has high output while also being highly resistant to COD.

[0092] The lens surface E2R is a convex lens surface. This makes the lateral (i.e., slow axis direction) component of the laser beam LB parallel. In this specification, parallel light includes a deviation (broadening) of ±4°, preferably ±2°, from perfectly parallel light. The lens surface E2R can be formed by RIE on the surface on the second end face E2 side of the semiconductor laminate 30.

[0093] The lens surface E2R may be set so that its focal plane is located at the boundary B between the first region 10 and the second region 20. This allows the lateral component of the laser light to be efficiently converted into parallel light.

[0094] Since the resonator of the semiconductor laser element L8 is located in the first region 10, the resonator length is constant regardless of the dimensions and shape of the second region, provided that the length of the first region 10 and the formation position of the diffraction grating 50 are constant. Therefore, even if the total length of the semiconductor laser element L8 increases by the protrusion of the lens surface E2R compared to the case where the lens surface E2R is not formed, the threshold current does not increase. As a result, the length D from the boundary B between the first region 10 and the second region 20 to the vertex of the lens surface E2R can be set to an arbitrary value. This allows the light to be widened in the lateral direction (y-direction) to a desired size in the second region 20 before passing through the lens surface E2R, where the lateral component of the laser light can be converted into parallel light.

[0095] The length D and the radius of curvature R of the lens surface E2R are set appropriately to match the lateral (y-direction) light confinement by the ridge portion of the first region 10. The length D may be, for example, 40 μm or more and 150 μm or less. The radius of curvature R of the lens surface E2R may be, for example, 25 μm or more and 70 μm or less. The center O of the radius of curvature R may be located within the second region 20.

[0096] The lens surface E2R may be spherical or aspherical. In particular, when the first region 10 is a multimode waveguide, an aspherical lens surface E2R is preferred. Since the width in the lateral direction (y direction) of a multimode waveguide is greater than the width in the lateral direction (y direction) of a single-mode waveguide, the light-emitting surface at the interface B between the first region 10 and the second region 20 is enlarged. In such cases, by making the lens surface E2R aspherical, the lateral component of the laser light can be efficiently converted into parallel light. Note that aspherical surfaces may include ellipsoids and parabolas.

[0097] Furthermore, as shown in Figure 12, the anti-reflective coating 74 provided on the second end face E2 is also provided on the lens surface E2R. The anti-reflective coating 74 provided on the lens surface E2R is arranged along the curved surface of the lens surface E2R. This reduces reflection at the second end face E2 and further improves resistance to COD.

[0098] (Embodiment 6) Figure 13 is a schematic top view representing the semiconductor laser element L9 of Embodiment 6. The semiconductor laser element L9 of Embodiment 6 has a similar configuration to the semiconductor laser element L4 of Modification 3, but differs from the semiconductor laser L4 in the following respects. The optical axis X2 of the resonator 12 of the semiconductor laser element L9 is tilted by an angle θ with respect to the normal X1 of the second end face E2 on the second end face E2 side, but is parallel to X1 on the first end face E1 side. In other words, the resonator 12 is bent in the middle when viewed from above.

[0099] Near the first end face E1, the optical axis X2 of the resonator 12 is perpendicular to the first end face E1, so light can be efficiently reflected at the first end face E1.

[0100] The semiconductor laser elements described above can be applied to both single-mode and multi-mode semiconductor laser elements. Semiconductor laser elements can be used in light source devices in various fields, such as projectors, communications, sensors, spectrometers, processing, and lighting.

[0101] The semiconductor laser elements of this disclosure can be appropriately combined from each modified example and each embodiment.

[0102] This disclosure includes the following components. (Section 1) A semiconductor laser element comprising a first region and a second region in which multiple semiconductor layers are stacked, The first region forms a resonator between the first end face and the mirror region including the diffraction grating. In a top view, the first region has an optical waveguide including a core region extending in the direction of the optical axis of the resonator and a cladding region sandwiching the core region in a direction perpendicular to the optical axis. The second region is adjacent to the first region in the direction of the optical axis, In a top view, the width of the second region in the direction perpendicular to the optical axis is greater than the width of the core region in the direction perpendicular to the optical axis. The second region is a semiconductor laser element having a second end face from which laser light is emitted. (Section 2) The semiconductor laser element according to item 1, wherein, in a top view, the optical waveguide is a single-mode waveguide in a direction perpendicular to the optical axis. (Section 3) A semiconductor laser element having multiple semiconductor layers stacked on top of each other, It comprises a channel waveguide, which is a first region, and a slab waveguide, which is a second region adjacent to the channel waveguide in the optical axis direction. The channel waveguide has a resonator formed between the first end face and the diffraction grating. The slab waveguide has a semiconductor laser element having a second end face on the opposite side of the first end face via the diffraction grating, from which laser light can be emitted. (Section 4) The semiconductor laser element according to item 3, wherein, in a top view, the channel waveguide is a single-mode waveguide in a direction perpendicular to the optical axis. (Section 5) The semiconductor laser element according to any one of claims 1 to 4, wherein, in a cross-sectional view in the optical axis direction, the ratio of the diffraction grating located in the first region to the entire diffraction grating is greater than 50%. (Section 6) The diffraction grating is provided only in the first region. The semiconductor laser element according to any one of items 1 to 5, wherein, in a cross-sectional view in the optical axis direction, the center of the diffraction grating is closer to the second end face than to the first end face. (Section 7) The width of the second end face perpendicular to the optical axis is greater than the width of the laser beam at the second end face. The semiconductor laser element according to any one of claims 1 to 6, wherein the width of the second region perpendicular to the optical axis is constant in the optical axis direction. (Section 8) The first region has a ridge, The diffraction grating is provided only in the first region. A semiconductor laser element according to any one of claims 1 to 7, wherein, in a top view, the diffraction grating is provided in the entire region where the ridge is located. (Section 9) A semiconductor laser element according to any one of items 1 to 8, wherein the length of the resonator in the optical axis direction is 1000 μm or more and 10000 μm or less. (Section 10) The semiconductor laser element according to any one of items 1 to 9, wherein the length of the second region in the optical axis direction is 0.01 times or more and 0.35 times or less the length of the resonator. (Section 11) The semiconductor laser element according to any one of claims 1 to 10, wherein the second end face has a lens surface at a position through which the laser light passes. (Section 12) A high-reflectivity coating is provided on the first end face. The semiconductor laser element according to any one of claims 1 to 11, wherein an anti-reflective coating is provided on the second end face. (Section 13) The first region and the second region include a first conductive semiconductor layer, a second conductive semiconductor layer, and an active layer disposed between the first conductive semiconductor layer and the second conductive semiconductor layer. The second conductive semiconductor layer in the first region is in contact with the first electrode. The semiconductor laser element according to any one of claims 1 to 12, wherein the diffraction grating is located in the first conductive semiconductor layer or the second conductive semiconductor layer. (Section 14) The semiconductor laser element according to item 13, wherein the second conductive semiconductor layer of the second region is not in contact with the first electrode. (Section 15) The semiconductor laser element according to claim 13 or 14, wherein the first conductive semiconductor layer, the second conductive semiconductor layer, and the active layer include a nitride semiconductor. (Section 16) A semiconductor laser element comprising a laminate in which multiple semiconductor layers are stacked, The laminated body is The first end face and, A second end face facing the first end face, from which laser light is emitted, The first region located on the first end face side, A second region located on the second end face side, Includes, The first region is, An optical waveguide comprising: a core region extending along a first direction from the first end face toward the second end face; and a plurality of cladding regions arranged on both sides of the core region in a second direction perpendicular to both the first direction and the stacking direction of the laminate; A diffraction grating provided in at least a portion of the first region, Includes, A semiconductor laser element in which the width of the second region is greater than the width of the core region. (Section 17) The semiconductor laser element according to claim 16, wherein the diffraction grating is provided in the portion of the first region adjacent to the second region. (Section 18) The semiconductor laser element according to claim 16 or 17, wherein, in a top view, the diffraction grating is provided over the entire region of the first region in which the core region is provided. (Section 19) The diffraction grating is provided only in the first region. The semiconductor laser element according to any one of claims 16 to 18, wherein the distance between the diffraction grating and the second end face is shorter than the distance between the diffraction grating and the first end face. (Section 20) The second region has a constant width, The width of the second end face is greater than the width of the laser beam at the second end face. A semiconductor laser element according to any one of claims 16 to 19. (Section 21) The first region has a ridge, The semiconductor laser element according to claim 18, wherein, in a top view, the diffraction grating is provided over the entire region where the ridge is provided. [Explanation of Symbols]

[0103] 10 First area 11 Core Areas 12 resonator 14 Mirror Area 14A First mirror region 14B Second Mirror Region 16, 18 Clad regions 20 Second area 25 Third medium 30 Semiconductor Stacks 300 circuit boards 310 First conductive semiconductor layer 312 n-side optical guide layer 314 n-side cladding layer 320 Active layer 330 Second conductive semiconductor layer 335 Ridge 42 2nd electrode 44 1st electrode 50 Diffraction Gratings 52 First medium 54 Second medium 60 Insulating layer 72 High-reflectivity coating 74 Anti-reflective coating 80 Window structure L1, L2, L3, L4, L5, L6, L7, L8, L9 Semiconductor laser elements E1 1st end surface E2 2nd end face E2R lens surface PS Phase Shift Structure

Claims

1. A semiconductor laser element comprising a first region and a second region in which multiple semiconductor layers are stacked, The first region forms a resonator between the first end face and the mirror region including the diffraction grating. In a top view, the first region has an optical waveguide including a core region extending in the direction of the optical axis of the resonator and a cladding region sandwiching the core region in a direction perpendicular to the optical axis. The second region is adjacent to the first region in the direction of the optical axis, In a top view, the width of the second region in the direction perpendicular to the optical axis is greater than the width of the core region in the direction perpendicular to the optical axis. The second region is a semiconductor laser element having a second end face from which laser light is emitted.

2. The semiconductor laser element according to claim 1, wherein, in a top view, the optical waveguide is a single-mode waveguide in a direction perpendicular to the optical axis.

3. A semiconductor laser element having multiple semiconductor layers stacked on top of each other, It comprises a channel waveguide, which is a first region, and a slab waveguide, which is a second region adjacent to the channel waveguide in the optical axis direction, The channel waveguide has a resonator formed between the first end face and the diffraction grating. The slab waveguide has a semiconductor laser element having a second end face on the opposite side of the first end face via the diffraction grating, from which laser light can be emitted.

4. The semiconductor laser element according to claim 3, wherein, in a top view, the channel waveguide is a single-mode waveguide in a direction perpendicular to the optical axis.

5. The semiconductor laser element according to any one of claims 1 to 4, wherein, in a cross-sectional view in the optical axis direction, the ratio of the diffraction grating arranged in the first region to the entire diffraction grating is greater than 50%.

6. The diffraction grating is provided only in the first region. The semiconductor laser element according to any one of claims 1 to 4, wherein, in a cross-sectional view in the optical axis direction, the center of the diffraction grating is closer to the second end face than to the first end face.

7. In a top view, the width of the second end face perpendicular to the optical axis is greater than the width of the laser beam at the second end face. A semiconductor laser element according to any one of claims 1 to 4, wherein, in a top view, the width of the second region perpendicular to the optical axis is constant in the optical axis direction.

8. The first region has a ridge, The diffraction grating is provided only in the first region. A semiconductor laser element according to any one of claims 1 to 4, wherein, in a top view, the diffraction grating is provided in the entire region where the ridge is located.

9. The semiconductor laser element according to any one of claims 1 to 4, wherein the length of the resonator in the optical axis direction is 1,000 μm or more and 10,000 μm or less.

10. The semiconductor laser element according to any one of claims 1 to 4, wherein the length of the second region in the optical axis direction is 0.01 times or more and 0.35 times or less the length of the resonator.

11. The semiconductor laser element according to any one of claims 1 to 4, wherein the second end face has a lens surface at a position through which the laser light passes.

12. A high-reflectivity coating is placed on the first end face, A semiconductor laser element according to any one of claims 1 to 4, wherein an anti-reflective coating is disposed on the second end face.

13. The first region and the second region include a first conductive semiconductor layer, a second conductive semiconductor layer, and an active layer disposed between the first conductive semiconductor layer and the second conductive semiconductor layer. The second conductive semiconductor layer in the first region is in contact with the first electrode. The semiconductor laser element according to any one of claims 1 to 4, wherein the diffraction grating is disposed in the first conductive semiconductor layer or the second conductive semiconductor layer.

14. The semiconductor laser element according to claim 13, wherein the second conductive semiconductor layer in the second region is not in contact with the first electrode.

15. The semiconductor laser element according to claim 13, wherein the first conductive semiconductor layer, the second conductive semiconductor layer, and the active layer include a nitride semiconductor.

16. A semiconductor laser element comprising a laminate in which multiple semiconductor layers are stacked, The laminated body is The first end face and A second end face facing the first end face, from which laser light is emitted, The first region located on the first end face side, The second region located on the second end face side, Includes, The first region is, An optical waveguide comprising: a core region extending along a first direction from the first end face toward the second end face; and a plurality of cladding regions arranged on both sides of the core region in a second direction perpendicular to both the first direction and the stacking direction of the laminate; A diffraction grating provided in at least a portion of the first region, Includes, A semiconductor laser element in which the width of the second region is greater than the width of the core region.

17. The semiconductor laser element according to claim 16, wherein the diffraction grating is provided in the portion of the first region adjacent to the second region.

18. The semiconductor laser element according to claim 16, wherein, in a top view, the diffraction grating is provided over the entire region of the first region in which the core region is provided.

19. The diffraction grating is provided only in the first region. The semiconductor laser element according to claim 16, wherein the distance between the diffraction grating and the second end face is shorter than the distance between the diffraction grating and the first end face.

20. The aforementioned second region has a constant width. The width of the second end face is greater than the width of the laser beam at the second end face. The semiconductor laser element according to claim 16.

21. The first region has a ridge, The semiconductor laser element according to claim 18, wherein, in a top view, the diffraction grating is provided over the entire region in which the ridge is provided.

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