Semiconductor laser with on-chip filtering structure and method of manufacturing the same

Abstract

The application provides a semiconductor laser with an on-chip filtering structure, comprising an N electrode, an N-type substrate, a buffer layer, an N-type confinement layer, a lower waveguide layer, an active region, an upper waveguide layer and a P-type confinement layer which are sequentially stacked from bottom to top, wherein the middle part of the P-type confinement layer is in a boss shape and two sides of the P-type confinement layer are provided with a step structure, the upper surface of the boss shape is covered with a cover layer, the upper surface and the side surface of the step structure are both covered with an insulating layer, the exposed area of the cover layer and the insulating layer is covered with a P electrode layer, and the protruding area of the middle part of the P-type confinement layer and the cover layer form a ridge of the semiconductor laser; a groove structure is formed in the ridge and comprises a plurality of tooth-shaped grooves and a plurality of strip-shaped grooves, and the plurality of tooth-shaped grooves and the plurality of strip-shaped grooves are arranged along the light-emitting direction of the semiconductor laser. The application can realize high-power output and effectively improve the lateral far-field characteristics.

Description

Technical Field

[0001] This invention relates to the field of semiconductor laser technology, and in particular to a semiconductor laser with an on-chip filter structure and its fabrication method. Background Technology

[0002] Semiconductor lasers possess advantages such as high efficiency, compactness, low cost, long lifespan, wide wavelength range, and ease of integration, making them ideal light sources for numerous fields including pumping, laser surgery, fiber optic communication, and lidar. In recent years, to meet market demands, further improving the brightness of semiconductor lasers—that is, increasing output power and reducing beam divergence—has become a hot research topic.

[0003] Common high-power ridge semiconductor lasers exhibit numerous lateral modes, characterized by typical multilobes and large divergence in the lateral far field. Increasing the operating current further degrades beam quality, increasing coupling difficulty in applications and necessitating complex subsequent optical designs. Commonly used methods such as angle cavities, external cavities, and phase control structures all face bottlenecks and limitations in terms of design, fabrication, and power. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a semiconductor laser with an on-chip filter structure and its fabrication method, which can achieve high power output and effectively improve lateral far-field characteristics.

[0005] One aspect of the present invention provides a semiconductor laser with an on-chip filtering structure, comprising: an N-face electrode, an N-type substrate, a buffer layer, an N-type confinement layer, a lower waveguide layer, an active region, an upper waveguide layer, and a P-type confinement layer stacked sequentially from bottom to top, wherein the P-type confinement layer has a protruding shape in the middle and stepped structures on both sides, the upper surface of the protruding shape is covered with a capping layer, the upper surface and the sides of the stepped structures are covered with an insulating layer, the exposed areas of the capping layer and the insulating layer are covered with the P-face electrode layer, the protruding area in the middle of the P-type confinement layer and the capping layer constitute the ridge of the semiconductor laser; a trench structure is formed in the ridge, including a plurality of toothed trenches and a plurality of striped trenches, the plurality of toothed trenches and the plurality of striped trenches are arranged along the light emission direction of the semiconductor laser.

[0006] In some exemplary embodiments of the present invention, the toothed groove is opened vertically downward from the contact surface of the capping layer and the P-side electrode layer, with the lowest position of the groove being between the contact surface of the P-type confinement layer and the capping layer and the contact surface of the P-type confinement layer and the upper waveguide layer, and the depth of the groove being 1 to 3 μm.

[0007] In some exemplary embodiments of the present invention, the toothed groove 121 is disposed on the side of the ridge near the front cavity surface of the semiconductor laser, on the side of the ridge near the rear cavity surface of the semiconductor laser, and / or on both sides of the upper surface of the ridge, and is symmetrical about the transverse centerline and / or longitudinal centerline of the light-emitting cavity surface of the semiconductor laser.

[0008] In some exemplary embodiments of the present invention, the toothed grooves are arranged periodically along the light emission direction of the semiconductor laser; wherein, there is a fixed gap between each period, and each period contains multiple independent toothed grooves with the same cross-sectional shape, including triangular, semi-circular, and semi-elliptical shapes. In some exemplary embodiments of the present invention, multiple strip-shaped grooves are formed vertically downward from the contact surface of the capping layer and the P-side electrode layer, with the lowest position of the grooves located between the contact surface of the P-type confinement layer and the capping layer and the contact surface of the P-type confinement layer and the upper waveguide layer, and the groove depth is 1 to 3 μm.

[0009] In some exemplary embodiments of the present invention, the strip-shaped grooves are arranged in a straight line and formed on both sides of the upper surface of the ridge along the light-emitting direction of the semiconductor laser, and are symmetrical about the transverse center line and / or longitudinal center line of the light-emitting cavity surface of the semiconductor laser. The multiple strip-shaped grooves and the multiple tooth-shaped grooves are spaced apart on one side of the tooth bottom, and the minimum spacing is zero.

[0010] In some exemplary embodiments of the present invention, the span between the two sides of any groove in the toothed groove is set to 0.5 to 10 μm; the span between the two sides of any groove in the strip-shaped groove is set to 0.5 to 10 μm.

[0011] In some exemplary embodiments of the present invention, the ratio of etched portion to unetched portion in the plurality of toothed grooves ranges from 2:8 to 8:2.

[0012] In some exemplary embodiments of the present invention, the material of the P-side electrode includes Ti, Pt, and Au; the material of the capping layer is P-type heavily doped GaSb; the material of the insulating layer is SiO2 or Si3N4; and the material of the P-type confinement layer is P-type doped Al. 0.5 The GaAsSb active region contains n quantum wells and n-1 barrier layers, where n is a positive integer, and the quantum well material is In. 0.18 GaSb, with Al as the barrier layer material. 0.25 GaAsSb; the upper and lower waveguide layers are made of the same material, undoped Al. 0.25 GaAsSb; the N-type confinement layer is made of N-type doped Al. 0.5 The material of the buffer layer is GaAsSb; the material of the N-type doped GaSb is GaSb; the material of the N-type substrate is GaSb; and the materials of the N-face electrodes include Ni, AuGe, and Au.

[0013] Another aspect of the present invention provides a method for fabricating a semiconductor laser with an on-chip filter structure, comprising: step S1, growing an epitaxial structure by sequentially growing a buffer layer, an N-type confinement layer, a lower waveguide layer, an active region, an upper waveguide layer, a P-type confinement layer, and a capping layer on an N-type substrate; step S2, etching away the capping layer and part of the P-type confinement layer on both sides of the mesa of the semiconductor laser to form ridges; step S3, etching tooth-shaped trenches and strip-shaped trenches in the trench structure within the ridges; step S4, growing an insulating layer on the upper surface and outer side of the stepped structure of the P-type confinement layer; and step S5, forming P-side electrodes on the ridges and the insulating layer, and forming N-side electrodes on the back side of the N-type substrate after thinning and polishing.

[0014] The semiconductor laser with an on-chip filter structure and its fabrication method provided in this invention have the following beneficial effects:

[0015] (1) The etching ratio can be flexibly adjusted, the position of the toothed groove can be adjusted according to different ridge widths, and the position of the edge groove can be adjusted according to the peak position of the carrier density distribution for precise control.

[0016] (2) During the transmission of the high-order mode optical field, multiple scattering and reflection occur at the groove. The fundamental mode energy is almost unaffected by the tooth structure, causing the near-field beam waist to contract, thereby achieving mode gain control, increasing the lasing threshold of the high-order mode, and thus reducing lateral divergence.

[0017] (3) The toothed groove can also effectively improve the lateral carrier accumulation and lateral current diffusion, and achieve a dual suppression effect with the strip groove. It alleviates the problem of additional gain of higher-order modes caused by lateral carrier accumulation at the edge of the ridge, improves injection efficiency, reduces threshold current, and achieves high brightness output.

[0018] (4) This structure can reduce the thermal gradient in the slow axis direction and reduce the filamentary effect. When applied in narrow ridge waveguides, it can achieve single transverse mode output with a wider output aperture, increase the operating current range of single transverse mode output, and improve device power.

[0019] (5) As a whole, the groove structure composed of toothed grooves and strip grooves has a wide range of applications. It can be applied not only to narrow ridges but also to wide ridges. At the same time, this structure can be combined with DFB structure, Taper structure, etc. and monolithically integrated into a single device to realize high mode purity and high power device.

[0020] (6) The trench structure has low requirements for photolithography precision and can be formed synchronously with large-size patterns. Attached Figure Description

[0021] Figure 1 A schematic diagram illustrating the effect of a semiconductor laser with an on-chip filter structure according to an embodiment of the present invention is shown.

[0022] Figure 2 A schematic cross-sectional view of a semiconductor laser with an on-chip filter structure according to an embodiment of the present invention is shown.

[0023] Figure 3 A schematic top view of a semiconductor laser with an on-chip filter structure according to an embodiment of the present invention is shown.

[0024] Figure 4 A partial view of a semiconductor laser with an on-chip filter structure according to an embodiment of the present invention is shown schematically.

[0025] Figure 5A The lateral far field of a semiconductor laser without an on-chip filter structure is schematically shown;

[0026] Figure 5B The lateral far field of a semiconductor laser with an on-chip filter structure according to an embodiment of the present invention is schematically shown;

[0027] Figure 6 The fabrication process of a semiconductor laser with an on-chip filter structure according to an embodiment of the present invention is illustrated schematically. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0029] Figure 1 The diagram schematically illustrates the effect of a semiconductor laser with an on-chip filter structure according to an embodiment of the present invention. Figure 2 A schematic cross-sectional view of a semiconductor laser with an on-chip filter structure according to an embodiment of the present invention is shown. Figure 3 A schematic top view of a semiconductor laser with an on-chip filter structure according to an embodiment of the present invention is shown.

[0030] like Figure 1 The diagram illustrates, schematically, the effect of a semiconductor laser with an on-chip filter structure according to an embodiment of the present invention. Figure 2 yes Figure 1 The image shows a cross-sectional view of the semiconductor laser along plane AA. Figure 3 yes Figure 1 The image shows a top view of a semiconductor laser. Please also refer to... Figures 1-3In this embodiment, a semiconductor laser with an on-chip filtering structure includes, from bottom to top, an N-face electrode 11, an N-type substrate 10, a buffer layer 9, an N-type confinement layer 8, a lower waveguide layer 7, an active region 6, an upper waveguide layer 5, and a P-type confinement layer 4. The P-type confinement layer has a raised section in the middle and stepped structures on both sides. The upper surface of the raised section is covered with a capping layer 2. The upper surface and sides of the stepped structures are covered with insulating layers 3. The exposed areas of the capping layer 2 and insulating layer 3 are covered with the P-face electrode layer 1. The raised section in the middle of the P-type confinement layer 4 and the capping layer 2 form a ridge of the semiconductor laser, within which a trench structure 12 is formed. However, those skilled in the art should understand that… Figures 1-3 The trench structure 12 shown is merely an example and does not limit the position and shape of the trench structure 12. The composition, position, shape and function of the trench structure 12 will be further explained with reference to the accompanying drawings.

[0031] Please refer to now. Figure 3 ,like Figure 3 As shown, in the illustrated example, the trench structure 12 includes a plurality of toothed trenches 121 and a plurality of striped trenches 122, all of which are arranged along the light emission direction of the semiconductor laser. Specifically, the arrangement direction of the plurality of toothed trenches 121 refers to... Figure 3 The direction of the line connecting the center points of the interconnecting teeth, and the direction of the arrangement of the multiple strip grooves 122, is a straight line of a continuous strip groove 122. The light output direction is the direction in which light is emitted from the semiconductor laser. The multiple toothed grooves 121 and the multiple strip grooves 122 are all arranged along the light output direction of the semiconductor laser, increasing the reflection and scattering surface for higher-order mode transmission, thereby having stronger filtering capability and achieving low divergence output without affecting the original ridge waveguide output power.

[0032] In some examples, the toothed grooves 121 are disposed on the side of the ridge near the front cavity surface of the semiconductor laser, on the side of the ridge near the rear cavity surface of the semiconductor laser, and / or on both sides of the upper surface of the ridge, and are symmetrical about the transverse centerline and / or longitudinal centerline of the output cavity surface of the semiconductor laser. This arrangement is adopted to ensure that the toothed grooves 121 are symmetrically and uniformly disposed on the ridge, thereby better controlling the filtering.

[0033] In some examples, the toothed grooves 121 are periodically arranged along the light emission direction of the semiconductor laser, with a fixed gap between each period. Each period contains multiple independent toothed grooves with the same cross-sectional shape, including but not limited to triangular, semi-circular, and semi-elliptical shapes. Figure 3In the example shown, the toothed groove 121 has 16 individual toothed grooves, with 4 individual toothed grooves forming a cycle, and 2 cycles arranged in a row, respectively located on both sides of the ridge. It should be noted that the 16 individual toothed grooves are only an example and do not limit the number and periodic arrangement of the toothed grooves 121.

[0034] Please continue to refer to Figure 3 In this embodiment, the strip groove 122 is arranged in a straight line and formed on both sides of the upper surface of the ridge along the light output direction of the semiconductor laser. It is symmetrical about the transverse center line and / or longitudinal center line of the light output cavity surface of the semiconductor laser. The purpose of this arrangement is the same as that of the toothed groove 121, so it will not be described again.

[0035] In some examples, multiple toothed trenches are etched. During the transmission of higher-order mode light fields, multiple scattering and reflection occur at the trenches, and the fundamental mode energy is almost unaffected by the toothed structure. This causes near-field beam waist contraction, enabling mode gain modulation, increasing the lasing threshold of higher-order modes, and thus reducing lateral divergence. The toothed trenches can also effectively improve lateral carrier accumulation and lateral current diffusion, achieving a dual suppression effect with the strip trenches. This alleviates the problem of additional gain in higher-order modes caused by lateral carrier accumulation at the ridge edge, improves injection efficiency, reduces threshold current, and achieves high-brightness output.

[0036] In some examples, the multiple strip grooves 122 and the multiple toothed grooves 121 are spaced apart on one side of the tooth root, and the minimum spacing is zero. The minimum spacing is zero when the tooth root of the toothed groove 121 coincides with the strip groove 122, which also means that the strip groove 122 cannot pass through the middle of the toothed groove 121.

[0037] Please continue to refer to Figure 3 In this embodiment, L is the ridge width, D is the distance between the two strip grooves 122, T is the width of the root of the independent tooth groove 121, and d is the distance between the tip of the independent tooth groove 121 and the edge of the ridge. Based on the lateral carrier distribution, the distance D between the two strip grooves 122 is 9L / 10. The peak position of the first-order side mode is located at a distance of L / 4 from the edge of the ridge, the peak position of the second-order side mode is located at a distance of L / 6 from the edge of the ridge, and the peak positions of the third-order side mode are L / 8 and 3L / 8. Preferably, to ensure that the tooth groove 121 better acts on the first-order side mode, the distance d between the tip of the independent tooth groove 121 and the edge of the ridge is d = L / 4.

[0038] Figure 4 A partial view of a semiconductor laser with an on-chip filter structure according to an embodiment of the present invention is schematically shown. Figure 4 yes Figure 2 A partial view of the sectional view shown.

[0039] like Figure 4 As shown, the groove structure 12 within the ridge is illustrated. Figure 4 This is for illustrative purposes only and does not reflect proportional relationships. In this embodiment, d1 is the span between the two sides of any groove in the toothed groove 121, and d2 is the span between the two sides of any groove in the strip groove 122. In some examples, d1 and d2 are both set to a range of 0.5 to 10 μm.

[0040] In some examples, the toothed groove 121 is opened vertically downward from the contact surface between the capping layer 2 and the P-surface electrode layer 1. The lowest position of the opening is between the contact surface between the P-type confinement layer 4 and the capping layer 2 and the contact surface between the P-type confinement layer 4 and the upper waveguide layer 5. The opening depth of the toothed groove 121 is h1, and h1 is between 1 and 3 μm.

[0041] In some examples, the strip trench 122 is opened vertically downward from the contact surface between the capping layer 2 and the P-surface electrode layer 1. The lowest position of the trench is between the contact surface between the P-type confinement layer 4 and the capping layer 2 and the contact surface between the P-type confinement layer 4 and the upper waveguide layer 5. The depth of the strip trench 122 is h2, which is between 1 and 3 μm.

[0042] Preferably, for ease of process operation, h1 and h2 can usually be set to the same value, but the present invention does not limit this.

[0043] In some examples, to ensure high loss in higher-order modes while reducing fundamental mode loss, the ratio of etched to unetched portions in multiple toothed grooves 121 ranges from 2:8 to 8:2.

[0044] Please continue reading. Figure 2 In some examples, the material of the P-side electrode 1 includes Ti, Pt, and Au; the material of the capping layer 2 is P-type heavily doped GaSb; the material of the insulating layer 3 includes SiO2 or Si3N4; and the material of the P-type confinement layer 4 is P-type doped Al. 0.5 GaAsSb; the active region 6 contains n quantum wells and n-1 barrier layers, where n is a positive integer, and the quantum well material is In. 0.18 GaSb, with Al as the barrier layer material. 0.25 GaAsSb; the upper waveguide layer 5 and the lower waveguide layer 7 are made of the same material, undoped Al. 0.25 GaAsSb; the N-type confinement layer 8 is made of N-type doped Al. 0.5 GaAsSb; the material of buffer layer 9 is N-type doped GaSb; the material of N-type substrate 10 is GaSb; the material of N-face electrode 11 includes Ni, AuGe, Au, etc.

[0045] Figure 5A The lateral far field of a semiconductor laser without an on-chip filter structure is schematically shown. Figure 5BThe lateral far field of a semiconductor laser with an on-chip filter structure according to an embodiment of the present invention is schematically shown.

[0046] like Figure 5A , Figure 5B As shown, the horizontal axis represents the far-field divergence angle, and the vertical axis represents the relative intensity. It can be seen that a semiconductor laser with an on-chip filter structure according to an embodiment of the present invention can significantly improve the far-field divergence angle.

[0047] Based on this, the present invention also discloses a method for fabricating a semiconductor laser with an on-chip filter structure as described above.

[0048] Figure 6 The fabrication process of a semiconductor laser with an on-chip filter structure according to an embodiment of the present invention is illustrated schematically.

[0049] like Figure 6 As shown in this embodiment, a method for fabricating a semiconductor laser with an on-chip filter structure includes:

[0050] Step S1: Grow the epitaxial structure by sequentially growing a buffer layer 9, an N-type confinement layer 8, a lower waveguide layer 7, an active region 6, an upper waveguide layer 5, a P-type confinement layer 4, and a capping layer 2 on an N-type substrate 10. Step S2: Etch away the capping layer 2 and part of the P-type confinement layer 4 on both sides of the semiconductor laser mesa to form ridges.

[0051] Alternatively, the ridges can be formed by wet etching or inductively coupled plasma (ICP) dry etching.

[0052] Step S3: Etch the toothed grooves 121 and strip grooves 122 in the groove structure 12 in the ridge.

[0053] Optionally, the toothed grooves 121 and strip grooves 122 in the trench structure 12 can also be formed by simultaneous etching after photolithography, and the pattern transfer is achieved by dry etching. The advantage of dry etching is that it can form the vertical sidewalls of the structure.

[0054] Step S4: An insulating layer 3 is grown on the upper surface and outer surface of the stepped structure of the P-type confinement layer 4.

[0055] Optionally, step S4 can employ metal-organic chemical vapor deposition (MOCVD) to grow the insulating layer.

[0056] In step S5, a P-side electrode 1 is formed on the ridge and insulating layer 3, and an N-side electrode 11 is formed on the back side of the N-type substrate 10 after thinning and polishing.

[0057] Optionally, ICP or reactive ion etching (RIE) can be used to etch away the insulating layer on the ridge, avoiding the trench structure, to form an electrical injection window. A P-surface electrode 1 can be formed on the ridge and insulating layer 3 using magnetron sputtering or electron beam evaporation.

[0058] Optionally, after steps S1 to S5, the formed wafer is cleaved into bars, and antireflection and high-reflection films are deposited on the bars corresponding to the front and back cavity surfaces of the semiconductor laser, respectively. Finally, it is cleaved into individual dies and mounted on a heat sink for testing. A wafer refers to a processed wafer obtained after growing an epitaxial structure on an N-type substrate 10 and undergoing a series of processes such as photolithography, etching, and electrode growth. The size of a single laser can be 500*1500μm. 2 Antireflective coating materials can be made of Al2O3, while high-reflective coating materials can be made of Si|SiO2.

[0059] In summary, the semiconductor laser with on-chip filtering structure and its fabrication method provided by this invention, based on the near-field distribution characteristics of the laser, shows that the fundamental mode energy is mainly concentrated in the center of the ridge, while the higher-order side modes extend towards the edges. This allows for flexible adjustment of the etching ratio, adjustment of the toothed groove position in conjunction with different ridge widths, and adjustment of the edge groove position based on the peak position of the carrier density distribution, enabling precise control. Furthermore, by etching multiple toothed grooves on the basis of the ridge-type semiconductor laser, multiple scattering and reflections occur at the grooves during the transmission of the higher-order mode light field. The fundamental mode energy is almost unaffected by the toothed structure, causing near-field beam waist contraction, achieving mode gain control, increasing the lasing threshold of higher-order modes, and thus reducing lateral divergence. The toothed grooves also effectively improve lateral carrier accumulation and lateral current diffusion, achieving a dual suppression effect with the striped grooves. This alleviates the problem of additional gain in higher-order modes caused by lateral carrier accumulation at the ridge edges, improves injection efficiency, reduces threshold current, and achieves high-brightness output.

[0060] Simultaneously, this structure reduces the thermal gradient along the slow axis and minimizes filamentation. In narrow ridge waveguides, it enables single-mode output with a wider output aperture, increases the operating current range of single-mode output, and improves device power. As a whole, the trench structure composed of toothed and striped trenches has a wide range of applications, not only for narrow ridges but also for wide ridges. It can be combined with DFB structures, Taper structures, etc., and monolithically integrated into a single device to achieve high-mode purity, high-power devices. Furthermore, this trench structure has low requirements for photolithography precision and can be formed simultaneously with large-size patterns.

[0061] This concludes the description of a semiconductor laser with an on-chip filter structure and its fabrication method. Based on this description, those skilled in the art should have a clear and accurate understanding of the present invention.

[0062] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A semiconductor laser with an on-chip filter structure, characterized in that, include: The N-type electrode (11), N-type substrate (10), buffer layer (9), N-type confinement layer (8), lower waveguide layer (7), active region (6), upper waveguide layer (5), and P-type confinement layer (4) are stacked sequentially from bottom to top. The P-type confinement layer (4) has a boss shape in the middle and stepped structures on both sides. The upper surface of the boss shape is covered with a capping layer (2). The upper surface and sides of the stepped structure are covered with an insulating layer (3). The exposed areas of the capping layer (2) and the insulating layer (3) are covered with P-type electrodes (1). The protruding area in the middle of the P-type confinement layer (4) and the capping layer (2) constitute the ridge of the semiconductor laser. The groove structure (12) is formed in the ridge and includes a plurality of toothed grooves (121) and a plurality of strip grooves (122), wherein the plurality of toothed grooves (121) and the plurality of strip grooves (122) are arranged along the light emission direction of the semiconductor laser; The plurality of toothed grooves (121) are disposed on both sides of the upper surface of the ridge and are symmetrical about the transverse centerline and / or longitudinal centerline of the light-emitting cavity surface of the semiconductor laser. The plurality of toothed grooves (121) are arranged periodically along the light-emitting direction of the semiconductor laser, with a fixed gap between each period. Each period contains a plurality of independent toothed grooves with the same cross-sectional shape, including triangular, semi-circular, and semi-elliptical shapes. The distance between the tooth tip of the toothed groove (121) and the edge of the ridge is one-quarter of the width of the ridge; The strip grooves (122) are arranged in a straight line and formed on both sides of the upper surface of the ridge along the light output direction of the semiconductor laser. They are symmetrical about the transverse center line and / or longitudinal center line of the light output cavity surface of the semiconductor laser. The multiple strip grooves (122) and the multiple toothed grooves (121) are spaced apart on one side of the tooth root, and the minimum spacing is zero.

2. The semiconductor laser according to claim 1, characterized in that, The toothed groove (121) is opened vertically downward from the contact surface of the capping layer (2) and the P-surface electrode (1), with the lowest position of the groove being between the contact surface of the P-type confinement layer (4) and the capping layer (2) and the contact surface of the P-type confinement layer (4) and the upper waveguide layer (5), and the depth of the groove is 1~3 μm.

3. The semiconductor laser according to claim 1, characterized in that, The plurality of strip-shaped trenches (122) are opened vertically downward from the contact surface of the capping layer (2) and the P-surface electrode (1), with the lowest position of the trenches being between the contact surface of the P-type confinement layer (4) and the capping layer (2) and the contact surface of the P-type confinement layer (4) and the upper waveguide layer (5), and the trench depth being 1 ~ 3 μm.

4. The semiconductor laser according to claim 1, characterized in that, The span between the two sides of any groove in the toothed groove (121) is set to 0.5 ~ 10 μm; The span between the two sides of any groove in the strip groove (122) is set to 0.5 ~ 10 μm.

5. The semiconductor laser according to claim 4, characterized in that, The ratio of etched to unetched portions in the plurality of toothed grooves (121) ranges from 2:8 to 8:

2.

6. The semiconductor laser according to claim 1, characterized in that, The materials of the P-side electrode (1) include Ti, Pt, and Au; The material of the capping layer (2) is P-type heavily doped GaSb; The material of the insulating layer (3) is SiO2 or Si3N4; The material of the P-type confinement layer (4) is P-type doped Al. 0.5 GaAsSb; The active region (6) comprises n quantum wells and n-1 barrier layers, where n is a positive integer, and the material of the quantum wells is In. 0.18 GaSb, the barrier layer is made of Al. 0.25 GaAsSb; The upper waveguide layer (5) and the lower waveguide layer (7) are made of the same material, which is undoped Al. 0.25 GaAsSb; The material of the N-type confinement layer (8) is N-type doped Al. 0.5 GaAsSb; The material of the buffer layer (9) is N-type doped GaSb; The material of the N-type substrate (10) is GaSb; and The materials of the N-face electrode (11) include Ni, AuGe, and Au.

7. A method for fabricating a semiconductor laser according to any one of claims 1 to 6, characterized in that, include: Step S1: Grow an epitaxial structure by sequentially growing a buffer layer (9), an N-type confinement layer (8), a lower waveguide layer (7), an active region (6), an upper waveguide layer (5), a P-type confinement layer (4), and a capping layer (2) on an N-type substrate (10). Step S2: Etch away the capping layer (2) and part of the P-type confinement layer (4) on both sides of the semiconductor laser mesa to form ridges; Step S3: Etch the toothed grooves (121) and strip grooves (122) in the groove structure (12) in the ridge respectively. Step S4, an insulating layer (3) is grown on the upper surface and outer surface of the stepped structure of the P-type confinement layer (4). Step S5: A P-side electrode (1) is formed on the ridge and the insulating layer (3), and an N-side electrode (11) is formed on the back side of the N-type substrate (10) after thinning and polishing.

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