Edge-emitting laser preparation method and edge-emitting laser

Abstract

The invention relates to the technical field of semiconductor lasers, and discloses an edge-emitting laser preparation method and an edge-emitting laser, and the edge-emitting laser preparation method comprises the steps: forming a main body structure which comprises a substrate layer, an active layer, a first semiconductor cladding layer and an ohmic layer which are stacked in sequence; the surface of the side, away from the first semiconductor cladding, of the ohmic layer is etched to form a ridge-shaped table-board structure with a first notch, the ridge-shaped table-board structure extends in the first direction, the first direction is the extension direction of the cavity length of the edge-emitting laser, and the first notch is located in the side, close to the light-emitting end face, of the ridge-shaped table-board structure; a first waveguide groove and a second waveguide groove which are arranged at an interval are formed in the ridge-shaped mesa structure, and both the first waveguide groove and the second waveguide groove extend in the first direction; and respectively forming a first electrode and a second electrode on two sides of the main body structure. The first gap reduces current carriers flowing to the light emitting end face.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor lasers, and in particular to a method for preparing an edge emitting laser and the edge emitting laser. Background Art

[0002] Edge emitting laser (EEL) is a laser based on compound semiconductor materials. By applying a forward voltage to the edge emitting laser and continuously injecting current, electron holes are recombined in the active region (gain medium) in the intrinsic layer to produce stimulated radiation photons. The photons repeatedly oscillate in the resonant cavity formed by the front and rear end faces of the edge emitting laser to stimulate more stimulated radiation photons in the active region, thereby achieving light amplification. When the gain of the photon exceeds the threshold, it can be emitted from the end face to form a laser. Due to the effect of stimulated radiation, the optical properties of photons are highly consistent, so lasers have better monochromaticity and directionality than ordinary light sources (sunlight / incandescent lamps / LEDs, etc.), and also have higher brightness. Edge emitting lasers have been widely used in industrial processing, communications, medical treatment and other fields due to their good optical properties, small size, low cost and simple packaging.

[0003] In order to meet the use requirements of edge-emitting lasers in high-power scenarios, the width of the edge-emitting laser strip is generally increased to increase the width of the edge-emitting laser light-emitting area, so that the edge-emitting laser is in a multi-mode lasing state. However, during the operation of the edge-emitting laser, the temperature distribution at the center and both sides of the light-emitting end face of the edge-emitting laser is uneven, resulting in an increase in the refractive index difference between the center and both sides of the light-emitting end face, resulting in a thermal lens effect. The thermal lens effect causes the light field distribution at the light-emitting end face of the edge-emitting laser to converge, resulting in a large far-field divergence angle of the edge-emitting laser, which in turn causes a sharp drop in beam quality. At the same time, an overly convergent light field will form an extremely high energy density at the light-emitting end face, thereby causing damage to the light-emitting end face. Summary of the invention

[0004] In view of this, the present invention provides a method for preparing an edge emitting laser and an edge emitting laser to solve the problem that during the operation of the edge emitting laser, the temperature distribution at the center and both sides of the light emitting end face of the edge emitting laser is uneven, resulting in an increase in the refractive index difference between the center and both sides of the light emitting end face and generating a thermal lens effect.

[0005] In a first aspect, the present invention provides a method for preparing an edge-emitting laser, comprising: forming a main structure, wherein the main structure comprises a substrate layer, an active layer, a first semiconductor cladding layer and an ohmic layer stacked in sequence; Etching is performed on a surface of the ohmic layer on a side away from the first semiconductor cladding layer to form a ridged mesa structure having a first notch, wherein the ridged mesa structure extends along a first direction, the first direction being an extension direction of the cavity length of the edge-emitting laser, and the first notch is located on a side of the ridged mesa structure close to a light-emitting end face; Forming a first waveguide groove and a second waveguide groove spaced apart from each other on the ridge-shaped mesa structure, wherein the first waveguide groove and the second waveguide groove both extend along the first direction; forming a first electrode on a surface of the ohmic layer facing away from the first semiconductor cladding layer; A second electrode is formed on a surface of the substrate layer that is away from the active layer.

[0006] The edge-emitting laser preparation method provided by the present invention has a first notch located on a side of a ridge-shaped mesa structure close to a light-emitting end face, and the first notch can reduce carriers flowing to the light-emitting end face, thereby weakening the aggregation degree of carriers near the light-emitting end face, and further reducing the carrier distribution density near the light-emitting end face, which helps to weaken the light field energy at the center of the light-emitting end face, thereby reducing the heat generated at the center of the light-emitting end face, thereby reducing the refractive index difference between the center of the light-emitting end face and both sides, effectively suppressing the generation of a thermal lens at the light-emitting end face, thereby avoiding the formation of a converging light field at the light-emitting end face, thereby reducing the far-field divergence angle, improving the light beam quality, and avoiding damage to the light-emitting end face.

[0007] In an optional implementation, the ridge-shaped mesa structure has a second notch, and the second notch is located on a side of the ridge-shaped mesa structure close to the reflective end face, and the reflective end face and the light emitting end face are arranged opposite to each other along the first direction.

[0008] The second notch is located on the side of the ridged mesa structure close to the reflective end face. The second notch can reduce the carriers flowing to the reflective end face, thereby weakening the aggregation of carriers near the reflective end face, and further weakening the carrier distribution density near the reflective end face, which helps to weaken the light field energy at the center of the reflective end face, thereby reducing the heat generated at the center of the reflective end face. As a result, the refractive index difference between the center and both sides of the reflective end face is reduced, effectively suppressing the generation of thermal lenses at the reflective end face, thereby avoiding the formation of a converging light field at the reflective end face, thereby reducing the far-field divergence angle, improving the light beam quality, and avoiding damage to the reflective end face.

[0009] In an optional implementation, the depth of the etching process is greater than or equal to the thickness of the ohmic layer and less than or equal to the sum of the thicknesses of the first semiconductor cladding layer and the ohmic layer.

[0010] In the present invention, electrical isolation can be achieved through etching, current expansion can be avoided, strong current limitation near the cavity surface of the edge-emitting laser can be ensured, and cavity surface damage caused by excessive light field near the cavity surface can be avoided, so as to improve the reliability of the edge-emitting laser. When the etching depth is less than the thickness of the ohmic layer, electrical isolation cannot be achieved. Secondly, when the etching depth is too large, the active layer will be damaged, thereby affecting the beam quality.

[0011] In an optional embodiment, the depths of the first waveguide groove and the second waveguide groove are both greater than the depth of the etching process; the depths of the first waveguide groove and the second waveguide groove are both greater than the thickness of the ohmic layer, and less than or equal to the sum of the thicknesses of the first semiconductor cladding and the ohmic layer.

[0012] In the present invention, the first waveguide groove and the second waveguide groove can limit the current, effectively enhancing the limiting effect on the lateral expansion of the current, so that the current density in the active area increases. Secondly, the first waveguide groove and the second waveguide groove can lead out the heat in the edge-emitting laser, thereby improving the heat dissipation capacity of the edge-emitting laser, improving the reliability and extending the service life. In addition, a too shallow waveguide groove will cause the light field to leak outside the waveguide, while a too deep waveguide groove will increase the scattering and absorption loss of light inside the waveguide.

[0013] In an optional embodiment, after forming the first waveguide groove and the second waveguide groove spaced apart on the ridged mesa structure, and before forming the first electrode on the surface of the ohmic layer facing away from the first semiconductor cladding layer, the method further includes: An insulating layer is formed on a surface of the ridged mesa structure on a side away from the substrate layer, and the insulating layer covers the inner walls of the first waveguide groove and the second waveguide groove; A portion of the insulating layer located on the electrical injection region of the ridge-shaped mesa structure is removed.

[0014] In the present invention, the insulating layer electrically isolates the first electrode from the ohmic layer to prevent the injected current from flowing in an unnecessary path, so as to ensure that the current can be injected into the edge-emitting laser according to the designed path, thereby helping to ensure that the current can be evenly distributed in the edge-emitting laser to improve the luminous efficiency and output power of the edge-emitting laser. In addition, the insulating layer limits the light field, effectively improving the interaction between carriers and photons in the active layer, thereby effectively improving the photoelectric conversion efficiency. Secondly, the insulating layer can effectively suppress the high-order modes in the slow axis direction, thereby reducing the slow axis divergence angle and improving the beam quality.

[0015] In an optional embodiment, the lengths of the first waveguide slot and the second waveguide slot along the first direction are both less than or equal to the cavity length of the edge-emitting laser, and the lengths of the first waveguide slot and the second waveguide slot along the first direction are both greater than the length of the electric injection region extending along the first direction.

[0016] In the present invention, a large amount of carrier accumulation at the edge of the electric injection zone is avoided, the edge peak of the near-field light spot of the edge-emitting laser is eliminated, and the damage to the cavity surface caused by the local excessive intensity of the light field in the electric injection zone is avoided, thereby improving the reliability of the edge-emitting laser.

[0017] In an optional embodiment, after forming the first electrode on the surface of the ohmic layer facing away from the first semiconductor cladding layer and before forming the second electrode on the surface of the substrate layer facing away from the active layer, the method further includes: Thinning a surface of the substrate layer that is away from the active layer; The surface of the thinned substrate layer is polished.

[0018] In the present invention, thinning the back substrate layer and polishing the back surface are both helpful to ensure the effective flow of carriers in the main structure of the laser, reduce unnecessary losses, and thus improve the luminous efficiency of the laser.

[0019] In a second aspect, the present invention further provides an edge emitting laser, comprising: A main structure, the main structure comprising a substrate layer, an active layer, a first semiconductor cladding layer and an ohmic layer stacked in sequence; A ridged mesa structure, wherein the ridged mesa structure has a first notch, the ridged mesa structure extends along a first direction, the first direction is the extension direction of the cavity length of the edge-emitting laser, and the first notch is located on a side of the ridged mesa structure close to the light-emitting end face; A first waveguide groove and a second waveguide groove are arranged at intervals, and are located on the ridge-shaped mesa structure, and the first waveguide groove and the second waveguide groove extend along the first direction; A first electrode is located on a surface of the ohmic layer facing away from the first semiconductor cladding layer; The second electrode is located on a surface of the substrate layer that is away from the active layer.

[0020] In the edge-emitting laser provided by the present invention, the first notch is located on the side of the ridge-shaped mesa structure close to the light-emitting end face, and the first notch can reduce the carriers flowing to the light-emitting end face, thereby weakening the aggregation degree of the carriers near the light-emitting end face, and further reducing the carrier distribution density near the light-emitting end face, which helps to weaken the light field energy at the center of the light-emitting end face, thereby reducing the heat generated at the center of the light-emitting end face, thereby reducing the refractive index difference between the center of the light-emitting end face and the two sides, effectively suppressing the generation of thermal lens at the light-emitting end face, thereby avoiding the formation of a converging light field at the light-emitting end face, thereby reducing the far-field divergence angle, improving the light beam quality, and avoiding damage to the light-emitting end face.

[0021] In an optional implementation, the ridge-shaped mesa structure has a second notch, and the second notch is located on a side of the ridge-shaped mesa structure close to the reflective end face, and the reflective end face and the light emitting end face are arranged opposite to each other along the first direction.

[0022] In an optional embodiment, it further includes an insulating layer, wherein the insulating layer is located between the first electrode and the ohmic layer, and the insulating layer covers the inner walls of the first waveguide slot and the second waveguide slot; The insulating layer has a through hole therein, and the through hole exposes the electrical injection region of the ridge-shaped mesa structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 is a schematic flow chart of a method for preparing an edge-emitting laser according to an embodiment of the present invention; Figure 2 It is a structural schematic diagram of the main structure in the preparation of the edge-emitting laser provided by an embodiment of the present invention; Figure 3 It is a schematic diagram of the structure of the main structure in the preparation of the edge-emitting laser provided by an embodiment of the present invention after photolithography of the first mask layer; Figure 4 It is a structural schematic diagram of a main structure in the preparation of an edge-emitting laser provided by an embodiment of the present invention, and a ridge-shaped mesa structure having a first notch and a second notch formed by etching; Figure 5 It is a schematic diagram of a main structure in the preparation of an edge-emitting laser provided by an embodiment of the present invention, a ridge-shaped mesa structure having a first notch and a second notch, and a structure after photolithography of a second mask layer; Figure 6 It is a structural schematic diagram of a main structure, a ridge-shaped mesa structure with a first notch and a second notch, a first waveguide groove, and a second waveguide groove in the preparation of an edge-emitting laser provided by an embodiment of the present invention; Figure 7 It is a structural schematic diagram of a main structure, a ridge-shaped mesa structure with a first notch and a second notch, a first waveguide groove, a second waveguide groove, and an insulating layer in the preparation of an edge-emitting laser provided by an embodiment of the present invention; Figure 8 It is a schematic diagram of the structure of the main body structure, the ridged table structure with the first notch and the second notch, the first waveguide groove, the second waveguide groove, the insulating layer, and the third mask layer after photolithography in the preparation of the edge-emitting laser provided by an embodiment of the present invention; Fig. 9 It is a schematic diagram of a main structure, a ridged table structure with a first notch and a second notch, a first waveguide groove, a second waveguide groove, and a structure after a portion of the insulating layer on the electric injection region is removed in the preparation of an edge-emitting laser provided by an embodiment of the present invention; Fig.10 It is a schematic structural diagram of a main structure, a ridged table structure with a first notch and a second notch, a first waveguide groove, a second waveguide groove, a portion of the insulating layer on the electric injection region removed, and a first electrode in the preparation of an edge-emitting laser provided by an embodiment of the present invention; Fig.11 It is a schematic structural diagram of a main structure, a ridged table structure with a first notch and a second notch, a first waveguide groove, a second waveguide groove, a portion of an insulating layer on an electric injection region removed, a first electrode, and a second electrode in the preparation of an edge-emitting laser provided by an embodiment of the present invention; Fig.12 It is a top view of the edge-emitting laser provided by an embodiment of the present invention with the first electrode and the insulating layer removed.

[0025] Description of reference numerals: 100. Main structure; 201, ridged mesa structure; 2011, first notch; 2012, second notch; 2013, electric injection region; 202, first waveguide groove; 203, second waveguide groove; 204, first electrode; 205, second electrode; 206, insulating layer; 301, a first mask layer; 302, a second mask layer; 303, a third mask layer. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only some structures related to the present invention are shown in the accompanying drawings, rather than all structures. In the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention. Various structural schematic diagrams according to embodiments of the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified for the purpose of clear expression, and some details may be omitted. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships between them are only exemplary, and may be deviated due to manufacturing tolerances or technical limitations in practice, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs. In the context of the present invention, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intermediate layer / element between them. In addition, if one layer / element is "on" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "below" the other layer / element.

[0027] During the operation of the edge-emitting laser, the temperature distribution at the center and both sides of the light-emitting end face of the edge-emitting laser is uneven, which increases the difference in refractive index between the center and both sides of the light-emitting end face, resulting in a thermal lens effect. The thermal lens effect causes the light field distribution at the light-emitting end face of the edge-emitting laser to converge, resulting in a large far-field divergence angle of the edge-emitting laser, which leads to a sharp drop in beam quality. At the same time, an overly convergent light field will form an extremely high energy density at the light-emitting end face, thereby causing damage to the light-emitting end face.

[0028] Therefore, in order to suppress the generation of thermal lens on the light-emitting end face, an embodiment of the present invention provides a method for preparing an edge-emitting laser. Figure 1 is a flow chart of a method for preparing an edge-emitting laser according to an embodiment of the present invention, Figures 2 to 11 It is a schematic diagram of the structure corresponding to each process step. The preparation method comprises the following steps: S101, reference Figure 2 , forming a main structure 100, the main structure 100 includes a substrate layer, an active layer, a first semiconductor cladding layer and an ohmic layer stacked in sequence.

[0029] Specifically, a second semiconductor cladding layer is further provided between the substrate layer and the active layer, that is, the main structure 100 includes a substrate layer, a second semiconductor cladding layer, an active layer, a first semiconductor cladding layer and an ohmic layer stacked in sequence from bottom to top. Wherein, the material of the substrate layer may be gallium arsenide, indium phosphide or other common substrate materials, the second semiconductor cladding layer includes a second waveguide layer and a second confinement layer, the second confinement layer is formed on the upper surface of the substrate layer, the second waveguide layer is formed on the upper surface of the second confinement layer, the active layer is formed on the upper surface of the second waveguide layer, the active layer may be a quantum dot structure or a quantum well structure, the first semiconductor cladding layer includes a first waveguide layer and a first confinement layer, the first waveguide layer is formed on the upper surface of the active layer, and the first confinement layer is formed on the upper surface of the first waveguide layer; the materials of the first confinement layer, the second confinement layer, the first waveguide layer and the second waveguide layer may be gallium arsenide, gallium nitride or other compound semiconductors, the first confinement layer and the first waveguide layer are N-type semiconductors or P-type semiconductors, the second confinement layer and the second waveguide layer are P-type semiconductors or N-type semiconductors, when the first confinement layer and the first waveguide layer are N-type semiconductors, the second confinement layer and the second waveguide layer are P-type semiconductors, when the first confinement layer and the first waveguide layer are P-type semiconductors, the second confinement layer and the second waveguide layer are N-type semiconductors. The first semiconductor cladding layer and the second semiconductor cladding layer are used for optical confinement in the stacking direction. The ohmic layer is formed on the upper surface of the first confinement layer. The material of the ohmic layer is copper, silver or other materials with high conductivity.

[0030] S102, etching is performed on the surface of the side of the ohmic layer away from the first semiconductor layer to form a ridged mesa structure 201 having a first notch 2011, the ridged mesa structure 201 extends along a first direction, the first direction is the extension direction of the edge-emitting laser cavity length, and the first notch 2011 is located on a side of the ridged mesa structure 201 close to the light-emitting end face.

[0031] Specifically, a first mask layer 301 is spin-coated on the surface of the ohmic layer away from the first semiconductor cladding layer. The first mask layer 301 is a photoresist. Then, the photoresist in a set area is removed by photolithography to expose the ohmic layer below. Figure 3 As shown, the exposed portion is the edge position of the ohmic layer, and then the exposed portion of the ohmic layer is etched by an etching process, and the etching process includes dry etching and wet etching. Dry etching can perform high-directional etching on the main structure 100 to achieve the requirements for etching accuracy, and wet etching can increase the etching rate. After the etching is completed, the remaining first mask layer 301 is removed, as shown in FIG. Figure 4As shown, a ridged mesa structure 201 having a first notch 2011 is formed in the middle of the main structure 100. The ridged mesa structure 201 extends along a first direction, which is the extension direction of the cavity length of the edge-emitting laser. The first notch 2011 is located on the side of the ridged mesa structure 201 close to the light-emitting end face. The edge-emitting laser has a light-emitting end face and a reflection end face that are arranged opposite to each other along the first direction. The light-emitting end face is an anti-reflection film, and the reflection end face is a high-reflection film. There is a resonant cavity between the light-emitting end face and the reflection end face. When the edge-emitting laser is powered on, the electrons and holes in the active layer undergo radiation recombination, releasing photons, and the light is reflected back and forth in the resonant cavity, generating gain. The purpose of the photons reflecting back and forth in the resonant cavity is to make the excited light pass through the gain medium of the active layer multiple times to obtain sufficient amplification. When the light is amplified to the point where it can penetrate the anti-reflection film, the laser is emitted from one side of the anti-reflection film.

[0032] S103 , forming a first waveguide groove 202 and a second waveguide groove 203 spaced apart from each other on the ridge mesa structure 201 , wherein the first waveguide groove 202 and the second waveguide groove 203 extend along a first direction.

[0033] Specifically, refer to Figure 5 , a second mask layer 302 is spin-coated on the upper surface of the main structure 100, the second mask layer 302 is formed on the upper surface of the main structure 100, and the second mask layer 302 covers the ridged mesa structure 201, the second mask layer 302 is a photoresist, and the photoresist in the set area is removed by photolithography to expose the part of the ridged mesa structure 201 below, refer to Figure 6 The exposed ridge mesa structure 201 is etched by an etching process to form a first waveguide groove 202 and a second waveguide groove 203. The first waveguide groove 202 and the second waveguide groove 203 are arranged at intervals. The first waveguide groove 202 and the second waveguide groove 203 both extend along the first direction. The first waveguide groove 202 and the second waveguide groove 203 can limit the battery flow to the two sides perpendicular to the first direction, that is, limit the current flow to the two sides along the width direction of the edge-emitting laser cavity.

[0034] S104, forming a first electrode 204 on a surface of the ohmic contact layer facing away from the first semiconductor cladding layer.

[0035] refer to Fig.10 The material of the first electrode 204 can be silver or copper or other materials with high conductivity. The first electrode 204 can be formed by electron beam evaporation process or magnetron sputtering deposition process, which can quickly form the first electrode 204, and the formed first electrode 204 has high purity, reducing the influence of impurities on conductivity. The first electrode 204 contacts the upper surface of the ohmic layer of the ridged mesa to form an ohmic contact.

[0036] S105, forming a second electrode 205 on a surface of the substrate layer facing away from the active layer.

[0037] refer to Fig.11 The second electrode 205 is formed on the surface of the substrate layer on the side away from the second confinement layer. The second electrode 205 can be formed by electron beam evaporation or magnetron sputtering. Of course, a deposition process can also be used to form the first electrode and the second electrode on the two sides of the edge emitting laser. The material of the second electrode 205 can also be silver or copper or other materials with high conductivity.

[0038] In the edge-emitting laser preparation method provided by the present invention, the first notch 2011 can reduce the carriers flowing to the light-emitting end face, thereby weakening the aggregation degree of the carriers near the light-emitting end face, and further reducing the carrier distribution density near the light-emitting end face, which helps to weaken the light field energy at the center of the light-emitting end face, thereby reducing the heat generated at the center of the light-emitting end face. As a result, the refractive index difference between the center of the light-emitting end face and the two sides is reduced, and the generation of thermal lens at the light-emitting end face is effectively suppressed, thereby avoiding the formation of a converging light field at the light-emitting end face, thereby reducing the far-field divergence angle, improving the light beam quality, and avoiding damage to the light-emitting end face.

[0039] In this embodiment, if Fig.12 As shown, the ridged mesa structure 201 has a second notch 2012, and the second notch 2012 is located on one side of the ridged mesa structure 201 close to the reflective end face, and the reflective end face and the light emitting end face are arranged oppositely along the first direction. The first notch 2011 and the second notch 2012 can be arc-shaped notches, rectangular notches, or trapezoidal notches, and of course, can also be notches of other common shapes. The second notch 2012 can reduce the carriers flowing to the reflective end face, thereby reducing the concentration of carriers near the reflective end face, and further reducing the carrier distribution density near the reflective end face, which helps to reduce the light field energy at the center of the reflective end face, thereby reducing the heat generated at the center of the reflective end face, thereby reducing the refractive index difference between the center of the reflective end face and the two sides, effectively suppressing the generation of thermal lenses at the reflective end face, thereby avoiding the formation of a convergent light field at the reflective end face, thereby reducing the far-field divergence angle, improving the beam quality, and avoiding damage to the reflective end face.

[0040] In this embodiment, if Fig.12 As shown, the depth of the etching process is greater than or equal to the thickness of the ohmic layer, and less than or equal to the sum of the thickness of the first semiconductor cladding layer and the ohmic layer. By etching the main structure 100, a ridged mesa structure 201 is formed, and electrical isolation is achieved to avoid the expansion of the current, ensure a strong current limitation near the cavity surface of the edge-emitting laser, and avoid damage to the cavity surface caused by an excessively strong light field near the cavity surface, so as to improve the reliability of the edge-emitting laser. When the etching depth is less than the thickness of the ohmic layer, electrical isolation cannot be achieved. Secondly, when the etching depth is too large, the active layer will be damaged, thereby affecting the beam quality.

[0041] In this embodiment, if Fig.12 As shown, the depths of the first waveguide groove 202 and the second waveguide groove 203 are both greater than the depth of the etching process; the depths of the first waveguide groove 202 and the second waveguide groove 203 are both greater than the thickness of the ohmic layer, and less than or equal to the sum of the thicknesses of the first semiconductor cladding and the ohmic layer. The first waveguide groove 202 and the second waveguide groove 203 can limit the current, effectively enhancing the limiting effect on the lateral expansion of the current, so that the current density in the active area increases. Secondly, the first waveguide groove 202 and the second waveguide groove 203 can export the heat in the edge-emitting laser, thereby improving the heat dissipation capacity of the edge-emitting laser, improving the reliability, and extending the service life. In addition, a too shallow waveguide groove will cause the light field to leak outside the waveguide, while a too deep waveguide groove will increase the scattering and absorption loss of light inside the waveguide.

[0042] In some optional pairs of implementations, after forming the first waveguide groove 202 and the second waveguide groove 203 spaced apart on the ridged mesa structure 201, before forming the first electrode 204 on the surface of the ohmic layer facing away from the first semiconductor cladding, the steps further include: forming an insulating layer 206 on the surface of the ridged mesa structure 201 facing away from the substrate layer, and the insulating layer 206 covers the inner walls of the first waveguide groove 202 and the second waveguide groove 203; removing part of the insulating layer 206 located on the electric injection region 2013 of the ridged mesa structure 201. Specifically, as Figure 7 As shown, an insulating layer 206 is deposited on the upper surface of the main structure 100 by a vapor deposition process. The insulating layer 206 may be made of silicon nitride, silicon oxide or other dielectric materials. The insulating layer 206 covers the inner walls of the first waveguide groove 202 and the second waveguide groove 203, and covers the upper surface of the ridged mesa structure 201. Figure 8As shown, a third mask layer 303 is spin-coated on the upper surface of the insulating layer 206, and the third mask layer 303 is a photoresist. A set area is taken out in the third mask by photolithography to expose a portion of the insulating layer 206 located above the electric injection region 2013 of the ridge mesa structure 201, that is, the set area is located directly above the electric injection region 2013, and the set area has the same size and shape as the electric injection region 2013. Then, the exposed insulating layer 206 is etched by an etching process until the electric injection region 2013 (part of the ohmic layer) below the insulating layer 206 is exposed. In the present invention, the insulating layer 206 electrically isolates the first electrode 204 from the ohmic layer to prevent the injected current from flowing on an unnecessary path, so as to ensure that the current can be injected into the edge emitting laser according to the designed path, thereby helping to ensure that the current can be evenly distributed in the edge emitting laser, so as to improve the luminous efficiency and output power of the edge emitting laser. In addition, the insulating layer 206 limits the light field, effectively improving the interaction between carriers and photons in the active layer, thereby effectively improving the photoelectric conversion efficiency. Secondly, the insulating layer 206 can effectively suppress the high-order mode in the slow axis direction, thereby reducing the slow axis divergence angle and improving the beam quality.

[0043] In this embodiment, the lengths of the first waveguide slot 202 and the second waveguide slot 203 along the first direction are both less than or equal to the cavity length of the edge emitting laser, and the lengths of the first waveguide slot 202 and the second waveguide slot 203 along the first direction are both greater than the length of the electric injection zone 2013 extending along the first direction. This avoids the accumulation of carriers at the edge of the electric injection zone 2013, eliminates the edge peaks of the near-field light spot of the edge emitting laser, avoids the damage to the cavity surface caused by the local excessive intensity of the light field in the electric injection zone 2013, and improves the reliability of the edge emitting laser.

[0044] In some alternative implementations, after forming the first electrode 204 on the surface of the ohmic layer away from the first semiconductor cladding layer, and before forming the second electrode 205 on the surface of the substrate layer away from the active layer, the method further includes: thinning the surface of the substrate layer away from the active layer, and the substrate layer may be thinned by a chemical mechanical polishing process or an etching process, and then the surface of the thinned substrate layer is polished and cleaned. Thinning the back substrate layer and polishing the back improves the flatness and cleanliness of the lower surface of the substrate layer, which helps to ensure the effective flow of carriers in the laser main structure 100, reduce unnecessary losses, and thus improve the luminous efficiency of the laser.

[0045] In a second aspect, the present invention provides an edge emitting laser, which is prepared by the above-mentioned edge emitting laser preparation method, such as Fig.11 and Fig.12As shown, it includes a main structure 100, a ridged mesa structure 201, a first waveguide groove 202, a second waveguide groove 203, a first electrode 204 and a second electrode 205. The main structure 100 includes a substrate layer, an active layer, a first semiconductor cladding layer and an ohmic layer stacked in sequence; the ridged mesa structure 201 has a first notch 2011, the ridged mesa structure 201 extends along a first direction, the first direction is the extension direction of the cavity length of the edge-emitting laser, and the first notch 2011 is located on a side of the ridged mesa structure 201 close to the light-emitting end face; the first waveguide groove 202 and the second waveguide groove 203 are arranged at intervals, the first waveguide groove 202 and the second waveguide groove 203 are located on the ridged mesa structure 201, and the first waveguide groove 202 and the second waveguide groove 203 extend along the first direction; the first electrode 204 is located on a side surface of the ohmic layer away from the first semiconductor cladding layer; the second electrode 205 is located on a side surface of the substrate layer away from the active layer.

[0046] In the edge-emitting laser provided by the present invention, the first notch 2011 is located on the side of the ridge-shaped mesa structure 201 close to the light-emitting end face. The first notch 2011 can reduce the carriers flowing to the light-emitting end face, thereby weakening the aggregation degree of the carriers near the light-emitting end face, and further reducing the carrier distribution density near the light-emitting end face, which helps to weaken the light field energy at the center of the light-emitting end face, thereby reducing the heat generated at the center of the light-emitting end face. As a result, the refractive index difference between the center of the light-emitting end face and the two sides is reduced, which effectively suppresses the generation of thermal lens at the light-emitting end face, thereby avoiding the formation of a converging light field at the light-emitting end face, thereby reducing the far-field divergence angle, improving the light beam quality, and avoiding damage to the light-emitting end face.

[0047] The further functional description of each of the above structures is the same as that of the above corresponding preparation method embodiments, and will not be repeated here.

[0048] In the above description, the technical details of the patterning and etching of each layer are not described in detail. However, those skilled in the art should understand that various technical means can be used to form layers, regions, etc. of desired shapes. In addition, in order to form the same structure, those skilled in the art can also design methods that are not completely the same as the methods described above. In addition, although the various embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage.

[0049] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for preparing an edge-emitting laser, characterized in that: include: Forming a main structure (100), the main structure (100) comprising a substrate layer, an active layer, a first semiconductor cladding layer and an ohmic layer stacked in sequence; Etching is performed on a surface of the ohmic layer on a side facing away from the first semiconductor cladding layer to form a ridged mesa structure (201) having a first notch (2011), the ridged mesa structure (201) extending along a first direction, the first direction being the extension direction of the edge-emitting laser cavity length, and the first notch (2011) being located on a side of the ridged mesa structure (201) close to a light-emitting end face; A first waveguide groove (202) and a second waveguide groove (203) are formed on the ridge-shaped mesa structure (201), and the first waveguide groove (202) and the second waveguide groove (203) are both extended along the first direction; Forming a first electrode (204) on a surface of the ohmic layer facing away from the first semiconductor cladding layer; A second electrode (205) is formed on a surface of the substrate layer that is away from the active layer.

2. The method for preparing an edge emitting laser according to claim 1, characterized in that: The ridge-shaped mesa structure (201) has a second notch (2012), the second notch (2012) being located on a side of the ridge-shaped mesa structure (201) close to a reflective end face, the reflective end face and the light-emitting end face being arranged opposite to each other along the first direction.

3. The method for preparing an edge emitting laser according to claim 1, characterized in that: The depth of the etching process is greater than or equal to the thickness of the ohmic layer and less than or equal to the sum of the thicknesses of the first semiconductor cladding layer and the ohmic layer.

4. The method for preparing an edge emitting laser according to claim 1, characterized in that: The depths of the first waveguide groove (202) and the second waveguide groove (203) are both greater than the depth of the etching process; the depths of the first waveguide groove (202) and the second waveguide groove (203) are both greater than the thickness of the ohmic layer, and less than or equal to the sum of the thicknesses of the first semiconductor cladding and the ohmic layer.

5. The method for preparing an edge emitting laser according to claim 1, characterized in that: After forming a first waveguide groove (202) and a second waveguide groove (203) spaced apart on the ridge mesa structure (201), and before forming a first electrode (204) on a surface of the ohmic layer facing away from the first semiconductor cladding layer, the method further comprises: An insulating layer (206) is formed on a surface of the ridged mesa structure (201) that is away from the substrate layer, and the insulating layer (206) covers the inner walls of the first waveguide groove (202) and the second waveguide groove (203); A portion of the insulating layer (206) located on the electrical injection region (2013) of the ridge-shaped mesa structure (201) is removed.

6. The method for preparing an edge emitting laser according to claim 5, characterized in that: The lengths of the first waveguide slot (202) and the second waveguide slot (203) along the first direction are both less than or equal to the cavity length of the edge-emitting laser, and the lengths of the first waveguide slot (202) and the second waveguide slot (203) along the first direction are both greater than the length of the electric injection zone (2013) extending along the first direction.

7. The method for preparing an edge emitting laser according to claim 1, characterized in that: After forming a first electrode (204) on a surface of the ohmic layer facing away from the first semiconductor cladding layer, and before forming a second electrode (205) on a surface of the substrate layer facing away from the active layer, the method further comprises: Thinning a surface of the substrate layer that is away from the active layer; The surface of the thinned substrate layer is polished.

8. An edge emitting laser, characterized in that: include: A main body structure (100), the main body structure (100) comprising a substrate layer, an active layer, a first semiconductor cladding layer and an ohmic layer stacked in sequence; A ridged mesa structure (201), the ridged mesa structure (201) having a first notch (2011), the ridged mesa structure (201) extending along a first direction, the first direction being an extension direction of the cavity length of the edge-emitting laser, and the first notch (2011) being located on a side of the ridged mesa structure (201) close to a light-emitting end face; A first waveguide groove (202) and a second waveguide groove (203) arranged at intervals, located on the ridge-shaped mesa structure (201), and the first waveguide groove (202) and the second waveguide groove (203) extend along the first direction; A first electrode (204) is located on a surface of the ohmic layer facing away from the first semiconductor cladding layer; The second electrode (205) is located on a surface of the substrate layer that is away from the active layer.

9. The edge emitting laser according to claim 8, characterized in that The ridge-shaped mesa structure (201) has a second notch (2012), the second notch (2012) being located on a side of the ridge-shaped mesa structure (201) close to a reflective end face, the reflective end face and the light-emitting end face being arranged opposite to each other along the first direction.

10. The edge emitting laser according to claim 8, characterized in that It also includes an insulating layer (206), the insulating layer (206) is located between the first electrode (204) and the ohmic layer, and the insulating layer (206) covers the inner walls of the first waveguide slot (202) and the second waveguide slot (203); The insulating layer (206) has a through hole therein, and the through hole exposes the electrical injection region (2013) of the ridge-shaped mesa structure (201).

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