A semiconductor laser with asymmetric ridges for optical filtering

Abstract

The present invention relates to the field of semiconductor laser technology, and specifically discloses a semiconductor laser that realizes optical filtering with an asymmetric ridge. The upper surface of the P limiting layer of the laser has two parallel grooves, the portion between the grooves forms a ridge waveguide, and the two sides of the groove form shoulders; the connection between the front and rear parts of the ridge waveguide is a staggered connection, that is, a ridge waveguide staggered region with asymmetrical distribution in front and back is formed. The present invention controls the coupling loss of the high-order mode through the coupling integral efficiency of the fundamental mode mode field after the ridge waveguide deviates, filters the high-order light field in the laser, improves the purity of the fundamental mode output, and optimizes the light spot quality.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor lasers, and in particular to a semiconductor laser that realizes optical filtering with an asymmetric ridge. Background Art

[0002] The information disclosed in the background of the invention is only intended to enhance the understanding of the overall background of the invention and should not be necessarily regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Semiconductor lasers are the core of various optoelectronic devices and are widely used in information storage, laser display, industrial and medical equipment and other fields. 650nm semiconductor lasers are widely used in laser indication, laser processing, optical sensing, optical communication and medical fields due to their high beam quality, high cost performance and high photoelectric conversion rate. With the development of technology, improving the quality of the laser emission beam and improving the purity of the fundamental mode operation have become the main research and development directions of existing semiconductor lasers. Traditional ridge waveguide edge emitting semiconductor lasers are limited by their epitaxial growth control methods, coupled with the influence of the accuracy of the photolithography etching process and the influence of the defects of the active layer materials, resulting in poor output beam quality of the device, which is severely limited in applications such as optical communications and laser processing that require high beam quality, thereby limiting the development and progress of the laser industry.

[0004] In order to efficiently solve the existing difficulties of edge-emitting lasers, there are currently two main design ideas: one is to set a geometric structure or additional material that can achieve mode filtering at the position of the edge-emitting laser chip located in the resonant cavity or inside the epitaxial layered structure, to compensate or reduce the high-order modes when the laser resonates, increase the purity of the fundamental mode to achieve high-quality fundamental mode Gaussian spot output; the second is to filter at the laser cavity surface through high-precision coating and adding surface waveguide structure. The main limitation of the former is that the filtering structure set inside the laser will increase the laser resonance loss, reduce the laser current density, and thus reduce the laser efficiency, and at the same time, it has high requirements for the precision control of the tube core production process. The high-precision coating or cavity surface filtering structure proposed by the latter puts forward very stringent requirements on the accuracy of the lithography and coating processes, and also poses challenges to the device cost and chip yield, and is not suitable for large-scale production.

[0005] Chinese patent document CN111525391A discloses a semiconductor laser with three groove designs. Although the original intention of this design is to improve the fast-slow axis ratio of the laser far-field FFP spot through the action of multiple grooves, and to achieve an output close to a circular spot. The second groove can also achieve spot filtering with the help of a deep groove design that runs through the active layer. Different groove structures need to run through the active layer, with a small spacing, and multiple overlay processes will also increase the complexity of the lithography steps. The second and third grooves are on the light-emitting side of the ridge waveguide, and the improvement of the laser spot of the metal layer structure is at the expense of the laser photoelectric conversion efficiency and economy.

[0006] Chinese patent document CN111641104A discloses a semiconductor laser. The patent uses a number of current injection separation electrodes to optimize the laser field. Each separation electrode needs to be aligned with the current injection layer below, which greatly increases the complexity of the photolithography step. At the same time, the electric injection current diffusion area is large, which leads to a large heat diffusion area. If the current density is reduced by discrete electrodes to form a compensation structure, the interval between the discrete electrodes must be made very large, which will seriously reduce the current injection efficiency and reduce the device efficiency.

[0007] Chinese patent document CN113937616A discloses a ridge waveguide semiconductor laser. The patent describes that a ridge waveguide is etched on an epitaxial structure, and a grating is etched on the ridge waveguide near the rear cavity surface of the laser. The grating includes a mode selection area parallel to the rear cavity surface of the laser and a mode filtering area forming a preset angle with the rear cavity surface of the laser. The mode selection area is used to reflect the selected transverse mode back into the laser resonant cavity for oscillation and amplification; the mode filtering area is used to reflect the unselected transverse mode out of the laser resonant cavity. The semiconductor laser single tube provided by the patent selects a specific transverse mode by designing the grating size and morphology, and filters out other modes to achieve the purpose of improving the light field. However, like other grating structures, according to the refractive index of the semiconductor material, the calculated grating period is small and is at the wavelength level, which puts forward strict requirements on the photolithography process and etching process. In addition, the patent requires that an insulating layer be covered after the ridge waveguide grating structure is produced, and the insulating layer has a poor vertical surface coverage effect, which will greatly increase the risk of short circuit of the device and reduce the yield, and is not suitable for mass production. Summary of the invention

[0008] The present invention provides a semiconductor laser that realizes optical filtering with an asymmetric ridge. The present invention controls the coupling loss of the high-order mode by the coupling integral efficiency of the fundamental mode mode field after the ridge waveguide deviates, filters the high-order light field in the laser, improves the purity of the fundamental mode output, and optimizes the light spot quality. To achieve the above purpose, the present invention discloses the following technical solution.

[0009] A semiconductor laser for realizing optical filtering by using an asymmetric ridge, wherein the upper surface of the P limiting layer has two parallel grooves, the portion between the grooves forms a ridge waveguide, and the two sides of the grooves form shoulders. The connection between the front part and the rear part of the ridge waveguide is a staggered connection.

[0010] Furthermore, the offset width between the front portion and the rear portion is 0.1-3 μm. Preferably, the offset width increases with the increase of the ridge waveguide width.

[0011] Furthermore, the upper surface of the ridge waveguide is covered with an ohmic contact layer.

[0012] Furthermore, the P restriction layer outside the ridge waveguide area is covered with an insulating layer, and the insulating layer is not in contact with the ridge waveguide, and the ohmic contact layer, the insulating layer and the P restriction layer in the non-contact area are covered with a P-surface metal layer to form a conductive contact area between the P-surface metal layer and the ohmic contact layer.

[0013] Furthermore, the ridge width of the ridge waveguide is in the range of 1 μm to 200 μm, the length of the ridge waveguide is the same as the cavity length of a single semiconductor laser tube, and the height of the ridge waveguide or the depth of the groove is in the range of 0.1 μm to 5 μm.

[0014] Furthermore, the semiconductor laser further comprises, arranged in order from bottom to top: a substrate, an N confinement layer, an N waveguide layer, a quantum hydrazine active layer, and a P waveguide layer, wherein the P confinement layer covers the P waveguide layer.

[0015] Furthermore, the material of the substrate includes at least one of GaAs, InP, and Si.

[0016] Further, the material of the N confinement layer includes at least one of AlInP, AlGaInP, AlGaAs, and AlGaAsP. Optionally, the dopant in the N confinement layer is Si, and its doping concentration is 1E16-1E19 / cm 3 Optionally, the thickness of the N limiting layer is 1 μm to 3 μm.

[0017] Further, the material of the N waveguide layer includes at least one of AlInP, AlGaInP, AlGaAs, AlGaAsP, etc. Optionally, the thickness of the N waveguide layer is 0.05 μm to 3 μm.

[0018] Further, the quantum hydrazine active layer material is a sandwich layer structure formed by GaInP, AlGaInP, and GaInP. Optionally, the thickness of the quantum hydrazine active layer is 1nm to 40nm.

[0019] Further, the material of the P waveguide layer includes at least one of AlInP, AlGaInP, AlGaAs, AlGaAsP, etc. Optionally, the thickness of the P waveguide layer is 0.05 μm to 3 μm.

[0020] Further, the material of the P limiting layer includes at least one of AlInP, AlGaInP, AlGaAs, AlGaAsP, etc. Optionally, the dopant in the P limiting layer is Mg, and its doping concentration is 1E15-1E20 / cm 3 Optionally, the thickness of the P limiting layer is 1 μm to 3.0 μm.

[0021] Further, the material of the P-side metal layer includes at least two of titanium, platinum, gold, nickel, germanium, chromium, tin, etc. Optionally, the thickness of the P-side metal layer is 200nm-900nm.

[0022] Furthermore, the material of the insulating layer includes SiO 2 、Si 3 N 4 , AlN, etc. Optionally, the thickness of the insulating layer is 50nm-1000nm.

[0023] Furthermore, the cavity length of the semiconductor laser single tube is 250 μm to 1000 μm, the width is 150 μm to 450 μm, and the thickness is 100 μm to 300 μm.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] When the semiconductor laser is operating in the fundamental mode, the width of the ridge waveguide and the size of the laser structure are very demanding. At the same time, due to the limitations of the processing technology stability and precision stability during the production process, the actual output of the laser generates a multi-transverse mode output in the ridge waveguide area. The more modes supported by the laser waveguide, the more interference the multi-mode far-field light spots will have when the semiconductor laser is output, resulting in a non-Gaussian structure light spot distribution in the far field, or even multiple light spots, resulting in poor far-field light spot quality. Therefore, improving the purity of the laser waveguide fundamental mode operation will effectively improve the laser far-field light spot quality.

[0026] In order to overcome the above problems, the present invention adopts an asymmetric ridge waveguide design to laterally displace the front and rear parts of the ridge waveguide, so that the light mode in the waveguide will be coupled into the dislocated ridge waveguide at the dislocated position during the propagation oscillation process, thereby achieving low loss of the fundamental mode light field when coupled into the biased ridge waveguide, while the coupling loss of the high-order mode is high. Therefore, the coupling loss for the high-order mode is introduced in the light conduction process through the asymmetric ridge waveguide design, and the high-order mode is suppressed from participating in the laser oscillation, so as to achieve the mode filtering of the laser and the optimization of the far-field spot, effectively improve the purity of the fundamental mode output, and optimize the spot quality. In addition, the present invention can achieve light field high-order mode loss filtering with minimal chip structure changes and the simplest process flow, which is conducive to the simplification of the laser process, and will not affect the laser threshold and the difficulty of the back-end packaging process, and is particularly suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0028] Figure 1 Schematic diagram of the structure of an asymmetric ridge semiconductor laser in an embodiment of the present invention.

[0029] Figure 2 is a cross-sectional view of an asymmetric ridge semiconductor laser in an embodiment of the present invention.

[0030] Figure 3 is a top view of an asymmetric ridge semiconductor laser in an embodiment of the present invention.

[0031] Figure 4 1 is a diagram showing the transmission of the TE0 fundamental mode in the ridge waveguide structure of an asymmetric ridge semiconductor laser. The position indicated by the arrow is the misaligned region of the ridge waveguide.

[0032] Figure 5 This is a diagram showing the transmission of the TE1 high-order mode in the ridge waveguide structure of an asymmetric ridge semiconductor laser. The position indicated by the arrow is the misaligned area of ​​the ridge waveguide.

[0033] Figure 6 This is the far-field spot diagram of the TE0 fundamental mode.

[0034] Figure 7 This is the far-field spot diagram of the TE1 high-order mode.

[0035] Figure 8 This is a diagram of the transmission of the TE0 fundamental mode in the ridge waveguide structure of a symmetric ridge semiconductor laser.

[0036] Fig. 9This is a diagram of the transmission of TE1 high-order mode in the ridge waveguide structure of a symmetric ridge semiconductor laser.

[0037] Above Figure 1 The numbers in the figure represent: 1-substrate, 2-N confinement layer, 3-N waveguide layer, 4-quantum hydrazine active layer, 5-P waveguide layer, 6-P confinement layer, 7-ridge waveguide, 8-ohmic contact layer, 9-P-surface metal layer, 10-groove, 11-shoulder, 12-back part of ridge waveguide, 13-ridge waveguide dislocation region, 14-front part of ridge waveguide. DETAILED DESCRIPTION

[0038] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0039] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0040] For the convenience of description, if the words "up", "down", "left" and "right" appear in the present invention, they only indicate that they are consistent with the up, down, left and right directions of the drawings themselves, and do not limit the structure. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the equipment or components referred to need to have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. The technical solution of the present invention is further described in conjunction with the drawings and specific embodiments of the specification.

[0041] refer to Figures 1 to 3 , an example of an asymmetric ridge semiconductor laser, wherein the Figure 1A part of the laser is cut away to facilitate observation of its structure. Compared with the conventional semiconductor laser, the laser of this embodiment is characterized in that: the upper surface of the P confinement layer 6 of the laser has two parallel grooves 10, and the part of the P confinement layer 6 between the grooves 10 forms a ridge waveguide 7, and the two sides of the groove 10 form shoulders 11. The junction of the front part 14 and the rear part 12 of the ridge waveguide 7 is staggered, forming a ridge waveguide staggered region 13 with asymmetrical distribution in the front and back. As needed, the staggered width of the front part 14 and the rear part 12 can be arbitrarily selected between 0.1 and 3 μm (for example, 0.1 μm, 0.3 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, etc.), or other suitable sizes can be selected.

[0042] In addition, the ridge width of the ridge waveguide 7 can be arbitrarily selected between 1 μm and 200 μm, the length of the ridge waveguide 7 is the same as the cavity length of the semiconductor laser single tube, the height of the ridge waveguide 7 or the depth of the groove 10 can be arbitrarily selected between 0.1 μm and 5 μm, or other suitable sizes can be selected. For example, the width and depth of the ridge waveguide 7 are 3 μm and 5 μm respectively, and the offset width is 1 μm.

[0043] In this embodiment, the ridge waveguide is designed as an asymmetric structure in which the junction of the front part 14 and the rear part 12 is a transversely dislocated connection, so that the light mode in the waveguide is coupled into the dislocated ridge waveguide at the dislocated position during the propagation oscillation process, thereby achieving low loss of the fundamental mode light field when coupled into the biased ridge waveguide, while high coupling loss of the high-order mode. Therefore, through the asymmetric ridge waveguide design, coupling loss for the high-order mode is introduced in the light transmission process, the high-order mode is suppressed from participating in laser oscillation, and the mode filtering and far-field spot optimization of the laser are realized, which effectively improves the purity of the fundamental mode output and optimizes the spot quality.

[0044] Continue to refer Figures 1 to 3 In another embodiment, the upper surface of the ridge waveguide 7 of the asymmetric ridge semiconductor laser in the above embodiment is covered with an ohmic contact layer 8. The P confinement layer 6 outside the ridge waveguide 7 region is covered with an insulating layer 15, and the insulating layer 15 is not in contact with the ridge waveguide 7. The ohmic contact layer 8, the insulating layer 15, and the P confinement layer 6 in the non-contact region are covered with a P-surface metal layer 9, so as to form a conductive contact region between the P-surface metal layer 9 and the ohmic contact layer 8. The material of the insulating layer is SiO 2 , and its thickness is 200nm. In addition, the material of the insulating layer can also be Si 3 N 4 、SiC、AlN、Al 2 O 3 The thickness can be selected according to the needs.

[0045] Continue to refer Figures 1 to 3 In another embodiment, the asymmetric ridge semiconductor laser of the above embodiment further includes the following components arranged in order from bottom to top: substrate 1, N confinement layer 2, N waveguide layer 3, quantum hydrazine active layer 4, P waveguide layer 5, wherein the P confinement layer 6 covers the P waveguide layer 5. As an exemplary illustration, the substrate 1 is GaAs material. The N confinement layer 2 is AlInP material, and the thickness of the N-type confinement layer 2 is 1.05 μm, the dopant is Si, and the doping concentration is 1E16 / cm 3 . The N waveguide layer 3 is made of AlGaInP material, and the thickness of the N waveguide layer is 0.1μm. The quantum hydrazine active layer 4 is a sandwich structure formed by sequentially stacking a quantum well, a potential barrier, and a quantum hydrazine, and the materials thereof correspond to GaInP, AlGaInP, and GaInP respectively. The thickness of the potential barrier is 10nm, and the thickness of the quantum well is 5nm. The P waveguide layer 5 is made of AlGaInP material, and the thickness of the P waveguide layer 5 is 0.1μm. The P restriction layer 6 is made of AlInP material, and the thickness of the P restriction layer 6 is 1.2μm. The dopant in the P restriction layer 6 is Mg, and its doping concentration is 1E20 / cm 3 The thickness of the P-side metal layer is 700nm, and the material of the P-side metal layer is an alloy formed by titanium and platinum. It should be understood that the material, size, dopant, etc. of each structural layer illustrated in this embodiment include but are not limited to the above description, and the technicians can select or adjust according to the actual needs. This embodiment is mainly to show the structure of the above semiconductor laser more clearly and comprehensively.

[0046] In another embodiment, a preparation is provided. Figures 1 to 3 The method for preparing the asymmetric ridge semiconductor laser exemplified in the embodiment is as follows:

[0047] The laser substrate 1 is a GaAs crystal with a crystal orientation of (100) and a substrate thickness of 500 μm.

[0048] A transition layer is grown on the substrate 1 using MOCVD equipment. The transition layer material is Si-doped GaAs and has a thickness of 200 nm.

[0049] The N limiting layer 2 is grown on the transition layer by MOCVD equipment. The material of the N limiting layer 2 is Si-doped AlInP with a doping concentration of 1-4E18 / cm 3 , the thickness of N limiting layer 2 is 1000nm.

[0050] The N limiting layer 2 is formed by an N waveguide layer 3 grown by MOCVD equipment. The material is AlGaInP. The thickness of the N waveguide 3 is 90nm to 120nm. The Al composition is adjusted so that the AlGaInP layer presents a gradual distribution along the vertical growth plane, and the Al composition is higher in the direction away from the GaAs substrate.

[0051] An active layer 4 is grown on the N waveguide layer 3 , and the structure of the active layer 4 is a double quantum hydrazine sandwich structure active layer formed by stacking GaInP, AlGaInP, and GaInP from bottom to top, wherein the GaInP layer is 5 nm thick and the AlGaInP layer is 10 nm thick.

[0052] A P waveguide layer 5 is grown on the active layer 4. The material of the P waveguide layer 5 is AlGaInP with a thickness of 90nm to 120nm. The Al component in the material presents a gradual distribution along the direction perpendicular to the growth plane, and the Al component is higher in the direction away from the GaAs substrate.

[0053] A P limiting layer 6 is grown on the P waveguide layer 5. The material of the P limiting layer 6 is AlInP with a thickness of 1200nm. A GaInP barrier layer is grown in the P limiting layer 6. The barrier layer is located at the bottom of the P limiting layer 6 with a distance of 200nm. An AlGaInP barrier layer is grown on the top of the P limiting layer 6 with a thickness of 60nm.

[0054] An ohmic contact layer 8 is grown on the P confinement layer 6. The material of the ohmic contact layer is highly doped GaAs, and the thickness thereof is 140 nm.

[0055] After the epitaxial wafer growth is completed, photoresist is spin-coated on the surface of the ohmic contact layer 8, and ultraviolet lithography, development, and etching are performed. In the resist removal step, the ohmic contact layer 8 except the ridge waveguide is etched away according to a preset pattern.

[0056] Spin-coat the photoresist again, perform UV lithography, development, etching, and stripping steps, and etch out the ridge waveguide 7, groove 10, shoulder 11 structure, 12-ridge waveguide rear part, 13-ridge waveguide dislocation area, and 14-ridge waveguide front part according to the preset structural pattern.

[0057] The insulating layer 15 is grown on the prepared structure using PECVD technology. The insulating layer 15 is made of SiO 2 , the thickness of the insulating layer 15 is 200 nm.

[0058] After the growth of the insulating layer 15 is completed, photoresist is spin-coated on its surface, and ultraviolet lithography, development, etching, and desizing steps are performed to etch away the insulating layer 15 outside the ridge waveguide, leaving a window for exposing the ohmic contact layer 8.

[0059] Spin-coat photoresist on the surface, perform UV lithography and development, retain the photoresist at the boundary according to the preset structure pattern, use electron beam evaporation coating technology to evaporate the P-side metal layer 9 on the surface, and then use stripping technology to strip off the photoresist and metal at the boundary.

[0060] The side of the substrate 1 away from the P-face metal is thinned and polished to reduce the thickness of the substrate 1 to 100-120 μm, and the N-face metal is evaporated on the thinned and polished side.

[0061] The wafer is cleaved, coated and packaged to produce an asymmetric ridge semiconductor laser.

[0062] In another embodiment, a method for preparing a symmetrical ridge semiconductor laser is provided, and the specific process is as follows:

[0063] The laser substrate 1 is a GaAs crystal with a crystal orientation of (100) and a substrate thickness of 500 μm.

[0064] A transition layer is grown on the substrate 1 using MOCVD equipment. The transition layer material is Si-doped GaAs and has a thickness of 200 nm.

[0065] The N limiting layer 2 is grown on the transition layer by MOCVD equipment. The material of the N limiting layer 2 is Si-doped AlInP with a doping concentration of 1 to 4E18 / cm 3 , the thickness of N limiting layer 2 is 1000nm.

[0066] The N limiting layer 2 is formed by an N waveguide layer 3 grown by MOCVD equipment. The material is AlGaInP. The thickness of the N waveguide 3 is 90nm to 120nm. The Al composition is adjusted so that the AlGaInP layer presents a gradual distribution along the vertical growth plane, and the Al composition is higher in the direction away from the GaAs substrate.

[0067] An active layer 4 is grown on the N waveguide layer 3 , and the structure of the active layer 4 is a double quantum hydrazine sandwich structure active layer formed by stacking GaInP, AlGaInP, and GaInP from bottom to top, wherein the GaInP layer is 5 nm thick and the AlGaInP layer is 10 nm thick.

[0068] A P waveguide layer 5 is grown on the active layer 4. The material of the P waveguide layer 5 is AlGaInP with a thickness of 90nm to 120nm. The Al component in the material presents a gradual distribution along the direction perpendicular to the growth plane, and the Al component is higher in the direction away from the GaAs substrate.

[0069] A P limiting layer 6 is grown on the P waveguide layer 5. The material of the P limiting layer 6 is AlInP with a thickness of 1200nm. A GaInP barrier layer is grown in the P limiting layer 6. The barrier layer is located at the bottom of the P limiting layer 6 with a distance of 200nm. An AlGaInP barrier layer is grown on the top of the P limiting layer 6 with a thickness of 60nm.

[0070] An ohmic contact layer 8 is grown on the P confinement layer 6. The material of the ohmic contact layer is highly doped GaAs, and the thickness thereof is 140 nm.

[0071] After the epitaxial wafer growth is completed, photoresist is spin-coated on the surface of the ohmic contact layer 8, and ultraviolet lithography, development, and etching are performed. In the resist removal step, the ohmic contact layer 8 except the ridge waveguide is etched away according to a preset pattern.

[0072] The photoresist is spin-coated again, and ultraviolet lithography, development, etching, and stripping steps are performed to etch out the ridge waveguide 7, the groove 10, and the shoulder 11 structure according to the preset structural pattern.

[0073] The insulating layer 15 is grown on the prepared structure using PECVD technology. The insulating layer 15 is made of SiO 2 , the thickness of the insulating layer 15 is 200 nm.

[0074] After the growth of the insulating layer 15 is completed, photoresist is spin-coated on its surface, and ultraviolet lithography, development, etching, and desizing steps are performed to etch away the insulating layer 15 outside the ridge waveguide, leaving a window for exposing the ohmic contact layer 8.

[0075] Spin-coat the photoresist on the surface, perform ultraviolet lithography and development, retain the photoresist at the boundary according to the preset structure pattern, evaporate the P-side metal layer 9 on the surface by electron beam evaporation coating technology, and then use the stripping technology to strip off the photoresist and metal at the boundary;

[0076] The side of the substrate 1 away from the P-side metal is thinned and polished to reduce the thickness of the substrate 1 to 100-120 μm, and the N-side metal is evaporated on the thinned and polished side.

[0077] The wafer is cleaved, coated and packaged to produce a symmetrical ridge semiconductor laser.

[0078] Performance Testing

[0079] The performance of the asymmetric ridge semiconductor laser prepared in the above embodiment was tested, and the results are as follows: Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown. Among them, Figure 4Schematic diagram of the transmission of the TE0 fundamental mode in the ridge waveguide structure of the asymmetric ridge semiconductor laser. The position indicated by the arrow is the misaligned position of the ridge waveguide 13. Figure 5 Schematic diagram of the transmission of the TE1 high-order mode in the ridge waveguide structure of the asymmetric ridge semiconductor laser. The position indicated by the arrow is the misaligned position of the ridge waveguide 13. Figure 6 This is the far-field distribution diagram of the TE0 fundamental mode light field. Figure 7 This is the far-field distribution diagram of the TE1 high-order mode light field.

[0080] At the same time, the performance of the symmetrical ridge semiconductor laser prepared in the above embodiment was tested, and the results are as follows: Figure 8 , Fig. 9 As shown. Among them, Figure 8 Schematic diagram of the transmission of the TE0 fundamental mode in the ridge waveguide structure of the symmetric ridge semiconductor laser. Fig. 9 Schematic diagram of the transmission of TE1 high-order mode in the ridge waveguide structure of the symmetric ridge semiconductor laser.

[0081] from Figure 4 , Figure 5 , Figure 6 and Figure 7 It can be seen that the high-order modes in the asymmetric ridge semiconductor laser are redistributed at the ridge waveguide misalignment position 13, which causes the high-order modes to become unstable during transmission, increases the high-order mode loss, and realizes the optical filtering function for the high-order modes. The fundamental mode is less affected at the ridge waveguide misalignment position 13, the loss changes little, and the transmission direction and distribution are basically consistent with the initial state. Combined with the gain selection characteristics of the resonant cavity, the gain of the fundamental mode will be further enhanced, the high-order modes will be suppressed, and a pure fundamental mode mode far-field spot pattern will be formed (such as Figure 6 This shows that asymmetric ridge semiconductor lasers can effectively achieve optical filtering, thereby improving the far-field spot.

[0082] from Figure 8 and Fig. 9 It can be seen from the figure that there is no ridge waveguide misalignment position 13 in the symmetrical ridge semiconductor laser, so the transmission of the fundamental mode and high-order mode in the laser in the ridge waveguide is not affected. After the laser gain is amplified, the fundamental mode and high-order mode will form in the far field as shown in Figure 6 , Figure 7 The light spot shown, especially the high-order mode far field Figure 7 Interference will be formed on both sides of the fundamental mode far-field spot, affecting the spot quality of the laser. This shows that the symmetrical ridge semiconductor laser has no filtering function and cannot achieve spot optimization.

[0083] Finally, it should be noted that any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. Although the above describes the specific implementation of the present invention in conjunction with the drawings, it is not a limitation of the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, various modifications or deformations that can be made by those skilled in the art without creative labor are still within the protection scope of the present invention.

Claims

1. A semiconductor laser with an asymmetric ridge for optical filtering. It is characterized in that The upper surface of the P limiting layer of the laser has two parallel grooves, the part between the grooves forms a ridge waveguide, and the two sides of the groove form shoulders; the connection between the front part and the rear part of the ridge waveguide is staggered in the horizontal direction.

2. The semiconductor laser for realizing optical filtering by the asymmetric ridge according to claim 1, It is characterized in that The offset width between the front part and the rear part is 0.1-3 μm.

3. The semiconductor laser for realizing optical filtering by the asymmetric ridge according to claim 1, It is characterized in that The width of the dislocation increases as the width of the ridge waveguide increases.

4. The semiconductor laser for realizing optical filtering by asymmetric ridge according to claim 1, It is characterized in that The upper surface of the ridge waveguide is covered with an ohmic contact layer.

5. The semiconductor laser for realizing optical filtering by the asymmetric ridge according to claim 4, It is characterized in that The P restriction layer outside the ridge waveguide region is covered with an insulating layer, and the insulating layer is not in contact with the ridge waveguide. The ohmic contact layer, the insulating layer and the P restriction layer in the non-contact region are covered with a P-surface metal layer.

6. The semiconductor laser for realizing optical filtering by the asymmetric ridge according to claim 5, It is characterized in that The material of the P-side metal layer includes at least two of titanium, platinum, gold, nickel, germanium, chromium, and tin.

7. The semiconductor laser for realizing optical filtering by the asymmetric ridge according to claim 5, It is characterized in that The thickness of the P-side metal layer is 200nm~900nm.

8. The semiconductor laser for realizing optical filtering by the asymmetric ridge according to claim 1, It is characterized in that The ridge width of the ridge waveguide is in the range of 1 μm to 200 μm, the length of the ridge waveguide is the same as the cavity length of a single semiconductor laser tube, and the height of the ridge waveguide or the depth of the groove is in the range of 0.1 μm to 5 μm.

9. A semiconductor laser for realizing optical filtering by an asymmetric ridge according to any one of claims 1 to 8, It is characterized in that The semiconductor laser further comprises: a substrate, an N limiting layer, an N waveguide layer, a quantum hydrazine active layer, and a P waveguide layer, which are arranged in sequence from bottom to top, and the P limiting layer covers the P waveguide layer.

10. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 9, It is characterized in that The material of the substrate includes at least one of GaAs, InP and Si.

11. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 9, It is characterized in that The material of the N confinement layer includes at least one of GaAs, GaInP, AlInP, AlGaInP, AlGaAs, AlGaAsP, and InGaAsP.

12. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 9, It is characterized in that The dopant in the N limiting layer is Si, and its doping concentration is 1E16~1E19 / cm 3 .

13. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 9, It is characterized in that The thickness of the N limiting layer is 1 μm to 3 μm.

14. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 9, It is characterized in that The material of the N waveguide layer includes at least one of GaAs, GaInP, AlInP, AlGaInP, AlGaAs, AlGaAsP, and InGaAsP.

15. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 9, It is characterized in that The thickness of the N waveguide layer is 90nm-120nm.

16. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 9, It is characterized in that The quantum hydrazine active layer material is a sandwich layer structure formed by GaInP, AlGaInP and GaInP.

17. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 9, It is characterized in that The thickness of the quantum hydrazine active layer is 1 nm to 40 nm.

18. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 9, It is characterized in that The material of the P waveguide layer includes at least one of GaAs, GaInP, AlInP, AlGaInP, AlGaAs, AlGaAsP, and InGaAsP.

19. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 9, It is characterized in that The thickness of the P waveguide layer is 90nm~120nm.

20. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 9, It is characterized in that The material of the P confinement layer includes at least one of GaAs, GaInP, AlInP, AlGaInP, AlGaAs, AlGaAsP, and InGaAsP.

21. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 9, It is characterized in that The dopant in the P limiting layer is Mg, and its doping concentration is 1E15~1E20 / cm 3 .

22. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 9, It is characterized in that The thickness of the P limiting layer is 1 μm-3 μm.

23. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 5, It is characterized in that The material of the insulating layer includes SiO 2 、Si 3 N 4 , AlN, any one.

24. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 5, It is characterized in that The thickness of the insulating layer is 50nm~1000nm.

25. The semiconductor laser for realizing optical filtering by using an asymmetric ridge according to claim 5, It is characterized in that The cavity length of the semiconductor laser single tube is 250 μm-1000 μm, the width is 150 μm-450 μm, and the thickness is 100 μm-300 μm.

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