Single transverse mode semiconductor laser with self-stable light mode and manufacturing method thereof

Abstract

The invention belongs to the technical field of semiconductor lasers, and particularly discloses a single transverse mode semiconductor laser with a self-stable light mode and a manufacturing method thereof, the single transverse mode semiconductor laser comprises a substrate, a waveguide structure, an active layer and an electrode structure, a ridge waveguide is arranged above the waveguide structure, and an absorption regulation and control structure extending along a preset direction is formed on the ridge waveguide. The absorption regulation and control structure is composed of a local concave area formed through etching and a semiconductor material which is filled in the concave area and has an absorption characteristic, and the material generates selective absorption on a high-order transverse mode at the edge of the ridge waveguide under a laser working condition, so that the propagation loss of the high-order mode is improved; the self-stabilization control of the light mode is realized, and stable single transverse mode output is obtained. According to the invention, the loss difference between a high-order mode and a fundamental transverse mode is effectively improved from the structural level, so that the self-stabilization control of the transverse mode is realized on the premise of not changing the refractive index distribution of the main waveguide.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor laser technology, specifically relating to a self-stabilized single transverse mode semiconductor laser and its fabrication method. Background Technology

[0002] Semiconductor lasers are widely used in optical communication, laser processing, sensing, and display due to their compact structure, ease of integration, and high efficiency. A typical end-emitting semiconductor laser usually consists of a waveguide structure, an active layer, and a confinement layer epitaxially grown sequentially on a substrate, with a ridge waveguide formed by etching on top to confine the optical field in the lateral direction. The basic lateral mode is typically concentrated in the center of the ridge waveguide, while higher-order lateral modes exhibit higher intensity in regions near the sides of the ridge waveguide, making them more easily excited by increased operating current, structural deviations, or temperature changes.

[0003] To achieve higher quality laser output, stable operation of a single transverse mode is a crucial requirement for many applications. Therefore, existing technologies widely employ methods such as refractive index engineering, structural perturbation, and lateral loss control to suppress higher-order transverse modes. For example, the transverse refractive index distribution can be altered by adjusting the ridge waveguide width, etching depth, or waveguide layer thickness; the optical field distribution can be perturbed by tilting the ridge waveguide or using asymmetric waveguide structures; or absorption regions can be incorporated laterally to increase the loss of higher-order modes. These methods can limit the existence of higher-order modes to a certain extent.

[0004] However, refractive index engineering methods are usually sensitive to process tolerances, and deviations in etching depth or width can lead to significant changes in mode structure; structural perturbation methods require the introduction of special geometries, which are difficult to be compatible with mainstream process platforms; and most lateral absorption layer schemes require adjustments to the original epitaxial structure, which changes the overall waveguide refractive index characteristics and affects the stability of the fundamental transverse mode. Summary of the Invention

[0005] This invention addresses the problems in existing technologies by providing a self-stabilizing single transverse mode semiconductor laser and its fabrication method. It solves the problem that existing refractive index engineering methods are typically sensitive to process tolerances, with etching depth or width deviations causing significant changes in the mode structure. It also solves the problem that structural perturbation methods require the introduction of special geometries, making them incompatible with mainstream process platforms. Furthermore, it addresses the issue that most lateral absorption layer schemes require adjustments to the original epitaxial structure, altering the overall waveguide refractive index characteristics and affecting the stability of the fundamental transverse mode.

[0006] The technical solution adopted in this invention is as follows: In a first aspect, this application provides a mode-stable single transverse-mode semiconductor laser, comprising a substrate, a waveguide structure, an active layer and an electrode structure arranged sequentially, wherein the waveguide structure is provided with a ridge waveguide for guiding laser transmission. An absorption control structure extending along a preset direction is provided on the ridge waveguide. The absorption control structure is used to selectively lose the laser mode in the edge region of the ridge waveguide during laser oscillation. The absorption regulation structure is composed of a local regulation region formed by processing and a material with absorption properties placed in the region.

[0007] Furthermore, the localized control region is a recessed structure formed by etching, which extends along a direction perpendicular to the laser plane.

[0008] Furthermore, the recessed structure is disposed on both sides of the ridge waveguide along the length of the laser cavity, and the recessed structure extends at least partially into the internal region of the waveguide structure. The semiconductor material filled inside the recessed structure is an epitaxial material that matches the lattice constant of the sidewall material of the recessed structure.

[0009] Furthermore, the semiconductor material filling the recessed structure forms absorption centers through doping or defect state modulation, which are used to absorb the light field energy corresponding to higher-order transverse modes under laser operating conditions.

[0010] Furthermore, the electrode structure is configured to form a current injection opening at the top of the ridge waveguide.

[0011] Secondly, this application provides a method for fabricating a semiconductor laser, used to prepare the optical mode self-stabilized single transverse mode semiconductor laser described in the first aspect, comprising the following steps: Waveguide structures and active layers are epitaxially grown on a substrate; A ridge waveguide is formed on top of the waveguide structure using photolithography and etching processes. Photolithography is performed in the lateral region of the ridge waveguide to define a local control region, and an etching process is used to form a recessed structure extending in a direction perpendicular to the laser plane in the defined region. The wafer with the recessed structure is placed in an epitaxial growth device, and a semiconductor material with a lattice constant matching the sidewall material of the recessed structure is grown inside the recessed structure. By doping or defect state modulation, the material is made to have the characteristic of absorbing the light field energy corresponding to higher-order lateral modes. The wafer surface is wet-processed to remove residual material, and an insulating layer covering the entire surface is grown on it, forming an opening in the insulating layer at the top region of the ridge waveguide. A metal layer is formed above the insulating layer and the ohmic contact layer, such that the metal layer only contacts the ohmic contact layer at the opening of the insulating layer at the top of the ridge waveguide; A back electrode is formed on the back side of the substrate to complete the fabrication of the semiconductor laser.

[0012] Furthermore, the recessed structure is formed by a dry etching process, which includes an etching process using chlorine-based or fluorine-based gases as etching reaction gases.

[0013] Furthermore, the semiconductor material grown inside the recessed structure is one or more selected from GaAs, AlGaAs, GaInP, and AlInP.

[0014] Furthermore, in order to enable the material to absorb the light field energy corresponding to higher-order transverse modes by doping or defect state modulation, doping elements or defect states are introduced into the intrinsic material system of the semiconductor material to form absorption centers. The doping elements include one or more of C, Cr, Mg, B, and Zn.

[0015] Furthermore, the insulating layer is formed using a dielectric thin film growth process, and the dielectric thin film material includes one or more of SiO2, SiN, TiO, or Al2O3.

[0016] As can be seen from the above technical solutions, the advantages of the present invention are: This application employs an absorption modulation structure, consisting of recessed structures and epitaxially grown absorbing materials on both sides of the ridge waveguide, to achieve higher propagation loss of higher-order transverse modes at the edge region of the ridge waveguide during laser oscillation. This effectively enhances the loss difference between higher-order modes and the fundamental transverse mode at the structural level, thereby achieving self-stabilizing control of the transverse mode without altering the refractive index distribution of the main waveguide. Compared to traditional methods relying on narrow ridge structures, deep etching, or asymmetric waveguides to achieve single transverse modes, the local modulation structure and filling absorbing material used in this application are located outside the ridge waveguide, without interfering with the refractive index and gain distribution of the main waveguide region. This significantly improves the device's robustness to process deviations and batch consistency. The epitaxially grown material in the recessed structure is introduced into the absorption centers through doping or defect state engineering, giving it enhanced absorption capability for the optical field corresponding to higher-order transverse modes under laser operating conditions. This achieves selective suppression of higher-order modes, avoiding mode jumps caused by temperature drift, current changes, or structural micro-deviations, and facilitating stable single transverse mode output.

[0017] Regarding the electrode injection structure, by forming a current injection opening at the top of the ridge waveguide and isolating other areas with an insulating layer, the driving current is injected only from the ridge top. This further suppresses the gain conditions of higher-order modes from the carrier distribution perspective, enhancing the stability of the mode selectivity mechanism. This method does not require adjustments to the epitaxial main structure, avoids complex refractive index redesign, and has good process compatibility. The fabrication method uses dry etching to form a high aspect ratio recessed structure, wet etching to remove residual material and grow a dielectric thin film to form a surface insulating layer, and controlled current injection is achieved through open metal contacts. The entire process is fully compatible with mainstream epitaxial and processing technologies and is easy to implement on existing production lines. Attached Figure Description

[0018] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a conventional semiconductor laser chip; Figure 2 This is a schematic diagram showing the location of the light-emitting region in a conventional semiconductor laser. Figure 3 The diagram shows the basic mode distribution and waveguide loss of a conventional semiconductor laser. Figure 4 The diagram shows the high-order mode distribution and waveguide loss of a conventional semiconductor laser. Figure 5 This is a schematic diagram of the structure of the single transverse mode semiconductor laser of the present invention; Figure 6 This is a diagram showing the basic mode distribution and waveguide loss of the single transverse mode semiconductor laser of this invention; Figure 7 The diagram shows the high-order mode distribution and waveguide loss of the single transverse mode semiconductor laser of this invention. Figure 8 This is a flowchart of the method for fabricating a single transverse mode semiconductor laser according to the present invention.

[0020] In the figure: 1. Substrate; 2. N-type confinement layer; 3. N-type waveguide layer; 4. Quantum well active layer; 5. P-type waveguide layer; 6. P-type confinement layer; 7. Ridge waveguide; 8. Ohmic contact layer; 9. Insulating layer; 10. Metal layer; 11. Absorption modulation structure. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figures 1-4As shown, end-emitting semiconductor lasers typically employ a layered epitaxial structure. Their basic structure generally includes a substrate 1, a waveguide structure, an active layer, and electrode structures located on the upper and lower surfaces of the device. In typical fabrication processes, GaAs or InP is usually used as the substrate 1. An N-type confinement layer 2, an N-type waveguide layer 3, a quantum well active layer 4, a P-type waveguide layer 5, and a P-type confinement layer 6 are sequentially epitaxially grown on the substrate 1, thereby forming the refractive index and gain distribution in the longitudinal direction and achieving vertical confinement of the optical field. The quantum well active layer 4 is responsible for generating stimulated emission and is the core region for achieving laser oscillation.

[0023] To achieve lateral optical field confinement, conventional semiconductor lasers typically form a ridge waveguide 7 structure on the upper part of the epitaxial structure using photolithography and etching processes. The ridge waveguide 7 generally extends along the length of the laser cavity, and the etching depth and ridge width of its sidewalls determine the lateral refractive index distribution, thus affecting the optical field distribution of the fundamental lateral mode and higher-order lateral modes. The fundamental lateral mode is usually concentrated mainly in the central region of the ridge waveguide 7, while higher-order lateral modes have higher intensity densities near the sides of the ridge waveguide 7. Therefore, when the injection current increases, the temperature changes, or there are slight structural deviations, higher-order modes are more easily excited, leading to a decrease in beam quality.

[0024] A P-side metal electrode is typically formed above the ridge waveguide 7, with the metal layer 10 in direct contact with the underlying ohmic contact layer 8 for current injection. An N-side electrode is formed on the back side of the device after thinning and metal deposition, allowing the driving current to be injected vertically into the epitaxial structure. Injected carriers recombine in the quantum well region, generating stimulated emission and forming laser modes propagating along the cavity length. The existence and distribution of these modes depend on factors such as the transverse refractive index, waveguide layer thickness, the shape of the current injection region, and the gain distribution.

[0025] While maintaining simple device structures and mature fabrication processes, existing semiconductor lasers generally suffer from problems such as easy excitation of higher-order transverse modes and poor optical mode stability. When the ridge waveguide 7 structure design is limited or the manufacturing process deviation causes changes in the transverse refractive index distribution, higher-order modes may gain sufficient gain to participate in laser oscillation, causing mode jumps in the laser output and affecting beam quality and coupling efficiency.

[0026] Please see Figures 5-7 As shown, this application provides a single transverse mode semiconductor laser with self-stabilized optical mode. Based on a conventional semiconductor laser, an absorption control structure 11 extending along a preset direction is provided on the ridge waveguide 7. The absorption control structure 11 is used to selectively lose the laser mode in the edge region of the ridge waveguide 7 during laser oscillation. The absorption control structure 11 is composed of a local control region formed by processing and a material with absorption characteristics disposed in the region.

[0027] In this embodiment, the absorption control structure 11 is arranged on both sides of the ridge waveguide 7. This region is precisely where the intensity distribution of higher-order lateral modes is high. Therefore, placing the absorbing material here can generate a large propagation loss for higher-order modes. The position and range of the local control region are defined by a predefined photolithographic pattern, ensuring that the layout of the absorption control structure 11 is strictly aligned with the structure of the ridge waveguide 7, thus ensuring that the absorption structure effectively constrains the target mode. During the fabrication process, a local depression or material removal region is first formed, and then a material with absorption characteristics is introduced through epitaxy or deposition, so that the absorption structure extends along the cavity length in a continuous strip shape.

[0028] In one embodiment, photoresist is first coated on the waveguide surfaces on both sides of the ridge waveguide 7 after its formation, and the lateral position of the absorption control region is defined by a mask pattern. Subsequently, a material removal step is performed on these regions to form trenches that can accommodate the absorbing material, and then a highly photoabsorbent material is grown or deposited in the trenches, so that the absorption control structure 11 is continuously distributed along the cavity length direction.

[0029] In some embodiments, the local control region is a recessed structure formed by etching, and the recessed structure extends in a direction perpendicular to the laser plane.

[0030] In this structure, the depth of the recessed region extends vertically, allowing the absorption modulation structure 11 to partially penetrate the waveguide layer, thus getting closer to the main optical field distribution region of higher-order lateral modes. The sidewalls of the recessed structure are made of the original waveguide material, directly contacting the subsequently grown absorption material, which is beneficial for the lattice alignment of the epitaxial material. The etching process can be achieved through dry etching to obtain high sidewall verticality and aspect ratio.

[0031] In one embodiment, the sides of the ridge waveguide 7 are etched using an ICP dry etching process to a depth of hundreds of nanometers to several micrometers, forming a recessed structure with a narrow cross-section. This recessed structure extends through the upper region of the waveguide, allowing the subsequently filled absorbing material to be close to the optical field distribution area.

[0032] In some embodiments, the recessed structures are disposed on both sides of the ridge waveguide 7 along the length of the laser cavity, and the recessed structures extend at least partially into the internal region of the waveguide structure. The semiconductor material filled inside the recessed structures is an epitaxial material that matches the lattice constant of the sidewall material of the recessed structures.

[0033] The recessed structure is continuously arranged along the cavity length, ensuring that the absorption modulation structure 11 is completely aligned with the laser mode propagation direction, thereby stably suppressing higher-order modes throughout the entire cavity length. To obtain a smooth interface and good material bonding, a semiconductor material with a lattice matching that of the waveguide sidewall material is grown inside the recess, resulting in a low defect density at the material interface and enabling the formation of a high-quality, stable thin film. This epitaxial bonding method ensures that the filling material maintains stable absorption performance during laser operation.

[0034] In one embodiment, after the recess etching is completed, the wafer is placed in an MOCVD device, and a semiconductor material, such as AlGaAs or AlInP, with a lattice constant close to that of the sidewall structure is grown in the recess structure by adjusting the III-V epitaxial source, so that the interface maintains good crystal quality and lays the foundation for subsequent doping to form absorption centers.

[0035] In some embodiments, the semiconductor material filling the recessed structure forms absorption centers through doping or defect state modulation, which are used to absorb the light field energy corresponding to higher-order transverse modes under laser operating conditions.

[0036] By introducing specific doping elements into the epitaxial material within the depressions or by adjusting epitaxial conditions to generate controlled defect states, additional absorption levels can be formed near the material's bandgap, resulting in significant absorption near the laser wavelength. The optical field of higher-order transverse modes is mainly concentrated near the depressions, thus being preferentially absorbed by these absorption centers, while the fundamental transverse modes are less affected by absorption because their optical field is concentrated at the ridge centers. By adjusting the doping type and concentration, the absorption intensity can be altered to selectively suppress transverse modes of different orders.

[0037] In one embodiment, a zinc source is added during the MOCVD growth of the recess-filling material to achieve p-type doping, thereby forming a strong acceptor state in the material, enhancing the absorption capability of the corresponding wavelength, and significantly improving the cumulative loss of higher-order lateral modes in the cavity length direction.

[0038] In some embodiments, the electrode structure is configured to form a current injection opening at the top of the ridge waveguide 7.

[0039] In this embodiment, an opening in the insulating layer 9 is made in the top region of the ridge waveguide 7, so that the metal electrode only contacts the underlying ohmic contact layer 8 at this opening, thereby achieving directional current injection. Since the regions on both sides of the ridge waveguide 7 are covered by the insulating layer 9, the driving current will not be dispersed and injected into the recessed structure region, thereby avoiding changes in the carrier distribution of the absorbing material, ensuring the stability of the absorption center, and further enhancing the mode selectivity behavior.

[0040] In one embodiment, a SiN insulating film is grown on the wafer surface, and an opening region is defined on the top of the ridge waveguide 7 by photolithography. Subsequently, Ti / Pt / Au metal electrodes are deposited, so that the metal layer 10 is in direct contact with the ohmic contact layer 8 only in the opening region, while the structure below the recessed region is an insulating structure. Current is injected into the ridge center region only in the vertical direction, thereby achieving a stable fundamental mode gain distribution.

[0041] In some embodiments, please refer to Figure 8 As shown, this application provides a method for fabricating a semiconductor laser, used to prepare a self-stabilized single transverse-mode semiconductor laser, comprising the following steps: Step S1: Epitaxially grow a waveguide structure and an active layer on a substrate; In this step, a substrate with good thermal conductivity and suitable for III-V material systems, such as GaAs or InP, can be selected. Epitaxial growth can be performed using mainstream epitaxial techniques such as MOCVD or MBE, sequentially growing the waveguide layer, active layer, and upper cladding to form a complete refractive index and gain distribution structure in the longitudinal direction. The waveguide structure typically includes an upper waveguide layer, a lower waveguide layer, and an epitaxial layer that confines the light field propagation. The active layer employs a multi-quantum-well structure to improve optical gain. The epitaxial conditions in this step can be adjusted according to the material type, including growth temperature, V / III ratio, and growth rate, to obtain an epitaxial film with a smooth surface and good crystal quality.

[0042] In one embodiment, a cleaned GaAs substrate is placed into an MOCVD reaction chamber, and a lower waveguide layer, a quantum well layer, and an upper waveguide layer are grown sequentially using source gases such as TMAl, TMGa, and AsH3 in a predetermined ratio. A confinement layer is then grown on the surface of the upper waveguide layer to form the subsequent ridge waveguide region.

[0043] Step S2: Form a ridge waveguide on top of the waveguide structure using photolithography and etching processes; This step defines the lateral width of the ridge waveguide using photolithography, and then etches the ridge waveguide from the upper cladding to a predetermined depth using dry or wet etching methods, forming a lateral refractive index abrupt change structure. The width, etching depth, and sidewall morphology of the ridge waveguide are crucial parameters determining the lateral optical field distribution. This step ensures the ridge waveguide structure is uniform and continuous along the cavity length to meet the laser's optical field distribution control requirements. During etching, the etching rate and sidewall roughness must be controlled to reduce waveguide loss.

[0044] In one embodiment, the ridge waveguide pattern is defined by coating photoresist and using ultraviolet exposure. Then, the epitaxial layer above the ridge waveguide is vertically etched using an ICP device. The etching depth is controlled at the upper part of the waveguide structure, so that the formed ridge waveguide structure has high sidewall verticality.

[0045] Step S3: Perform photolithography in the transverse region of the ridge waveguide to define the local control region, and form a recessed structure extending in a direction perpendicular to the laser plane in the defined region by etching process; In this step, material is selectively removed from the lateral regions on both sides of the ridge waveguide to form a recessed structure extending in the longitudinal direction, facilitating subsequent filling with absorbing material. The recessed structure must be arranged parallel to the ridge waveguide, ensuring its continuous distribution along the cavity length. Dry etching techniques can be used to achieve a higher aspect ratio and more regular sidewall morphology. The depth of the recessed structure can extend to the upper part of the waveguide structure to enhance the overlap between the absorption modulation region and the higher-order lateral mode optical field.

[0046] In one embodiment, after photolithography is performed on both sides of the ridge waveguide, a chlorine-based gas is used as the etching gas source for deep etching, so that the longitudinal depth of the recessed structure reaches hundreds of nanometers to several micrometers, forming a regular groove-shaped recess for subsequent epitaxial growth of absorbing materials.

[0047] Step S4: Place the wafer with the recessed structure in an epitaxial growth device, and grow a semiconductor material with a lattice constant that matches the sidewall material of the recessed structure inside the recessed structure. By doping or defect state modulation, the material is made to have the characteristic of absorbing the light field energy corresponding to the higher-order lateral mode. In this step, the completed wafer is placed back into the epitaxial growth equipment, and selective epitaxy is performed inside the recess using a suitable III-V material system. To ensure growth quality and interface flatness, the filler material must maintain a lattice constant approximately equal to that of the sidewall material to avoid excessive strain leading to increased defect density. Specific dopant gases can be added during epitaxy, or controlled defects can be introduced by adjusting the epitaxial conditions to form absorption centers within the filler material. This allows the filler material to enhance absorption of the light field corresponding to higher-order lateral modes under laser operating conditions.

[0048] In one embodiment, a wafer is placed in an MOCVD device, and TMGa, TMAl, and AsH3 are introduced to grow AlGaAs-based materials. At the same time, a zinc source is added during the epitaxial process, so that the filler material has enhanced absorption capability near the target wavelength, thereby effectively suppressing the generation of higher-order lateral modes.

[0049] Step S5: Perform wet processing on the wafer surface to remove residual material and grow an insulating layer covering the entire surface, forming an opening in the insulating layer in the top region of the ridge waveguide. In this step, the wafer surface is first cleaned using a wet process to remove particles or residues formed during epitaxial growth. Next, a fully covering dielectric insulating layer is deposited on the wafer surface to serve as an isolation structure for subsequent metal electrodes. The insulating layer can be grown using processes such as PECVD, LPCVD, or ALD to achieve uniform film coverage. Subsequently, an opening is formed in the top region of the ridge waveguide using photolithography and etching, allowing current to be injected only from this opening, while the regions on both sides of the ridge waveguide remain covered by the insulating layer to prevent current diffusion into the absorption control structure 11.

[0050] In one embodiment, a wet cleaning process is first performed on the surface using diluted acid, followed by deposition of a SiN insulating film on the wafer surface. The pattern of the ridge top region is defined by photolithography, and the insulating layer in this region is removed using a plasma etching process, thereby forming an opening for current injection.

[0051] Step S6: Form a metal layer above the insulating layer and the ohmic contact layer, such that the metal layer only contacts the ohmic contact layer at the opening of the insulating layer at the top of the ridge waveguide. This step achieves electrical connection with the ohmic contact layer on the upper surface by depositing metal. Since the insulating layer covers both sides of the ridge waveguide, the metal layer can only contact the ohmic contact layer at the opening, thus forming a precise current injection path. This ensures that the driving current is mainly injected into the central region of the ridge in the vertical direction, avoiding current interference in the absorption and control region. The metal layer can be formed by evaporation or sputtering, and the ohmic contact performance can be improved through annealing.

[0052] In one embodiment, Ti, Pt and Au are sequentially deposited by electron beam evaporation to form a multilayer metal structure, and then a stable ohmic contact is achieved by an annealing process. The metal layers are completely isolated by an insulating film in the corresponding area of ​​the recessed structure, with no current injection.

[0053] Step S7: Form a back electrode on the back side of the substrate to complete the fabrication of the semiconductor laser.

[0054] In this step, the back side of the substrate is thinned, cleaned, and then metal is deposited to form the lower electrode. The back metal is typically made of AuGeNi-based materials to achieve good n-type ohmic contacts. Finally, the chip undergoes cavity dicing and coating before being put into the packaging or testing stage.

[0055] In one embodiment, the substrate is mechanically thinned to the target thickness, and an AuGeNi metal stack is deposited on the back side, followed by annealing to form a stable back electrode, thus completing the entire chip fabrication process.

[0056] In some embodiments, the recessed structure is formed by a dry etching process, which includes an etching process using chlorine-based or fluorine-based gases as etching reaction gases.

[0057] In this embodiment, the recessed structure is formed using a highly anisotropic etching method to achieve good sidewall verticality and aspect ratio. Using chlorine-based or fluorine-based gases as the reaction source can obtain a clean etching interface, avoiding excessive residue and facilitating subsequent epitaxial growth.

[0058] In one embodiment, ICP etching is performed using a Cl2 / BCl3 mixed gas to give the recessed structure a regular groove-shaped cross-section, which meets the processing requirements of the absorption control region.

[0059] In some embodiments, the semiconductor material grown inside the recessed structure is one or more selected from GaAs, AlGaAs, GaInP, and AlInP.

[0060] In this embodiment, the filling material inside the recess can be selected from different material systems according to the laser epitaxial system and the target absorption characteristics. These materials all have good lattice matching characteristics with GaAs or InP sidewall materials, which is beneficial to forming epitaxial films with low defect density.

[0061] In one embodiment, AlGaAs material is epitaxially grown inside the recessed structure, and the Al composition is adjusted to give the material the desired absorption capacity in the target wavelength range.

[0062] In some embodiments, in order to enable the material to absorb the light field energy corresponding to higher-order transverse modes by doping or defect state modulation, doping elements or defect states are introduced into the intrinsic material system of the semiconductor material to form absorption centers. The doping elements include one or more of C, Cr, Mg, B, and Zn.

[0063] In this embodiment, absorption centers are formed through doping or defect states, enabling the material to exhibit enhanced light absorption properties near the target wavelength. Different doping elements can form different energy level structures, which can be selected according to the actual absorption range and process conditions.

[0064] In one embodiment, a zinc source is introduced during the growth of the filler material, which enables the formed semiconductor material to have significant light absorption capability at the operating wavelength, thereby effectively suppressing higher-order modes.

[0065] In some embodiments, the insulating layer is formed using a dielectric thin film growth process, and the dielectric thin film material includes one or more of SiO2, SiN, TiO, or Al2O3.

[0066] In this embodiment, the insulating layer is deposited using a dielectric thin-film method. The thin-film material must possess good electrical insulation properties and surface coverage to ensure that the current injection path is limited to the top of the ridge waveguide. Different materials can be selected based on dielectric constant, pressure, temperature window, and process compatibility.

[0067] In one embodiment, SiO2 is grown on the wafer surface as an insulating layer using PECVD process, and an opening is made at the top of the ridge waveguide by photolithography and dry etching, so that the subsequently deposited metal electrode is connected to the ohmic contact layer only at this location.

[0068] It is understood that the systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer, which can be a personal computer, a laptop computer, a personal digital assistant, a tablet computer, a wearable device, or any combination of these devices.

[0069] In a typical configuration, a computer includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0070] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0071] Computer-readable media, including both permanent and non-permanent, removable and non-removable media, can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, disk storage, quantum memory, graphene-based storage media or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0072] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0073] It should be understood that although the terms first, second, third, etc., may be used to describe various information in one or more embodiments of this specification, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first information may also be referred to as second information without departing from the scope of one or more embodiments of this specification, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "in response to a determination," or "when," or "in the event of a determination."

[0074] The above description is merely a preferred embodiment of one or more embodiments of this specification and is not intended to limit the scope of one or more embodiments of this specification. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of this specification should be included within the protection scope of one or more embodiments of this specification.

Claims

1. A self-stabilized single transverse mode semiconductor laser, comprising a substrate (1), a waveguide structure, an active layer and an electrode structure arranged sequentially, wherein a ridge waveguide (7) for guiding laser transmission is provided in the waveguide structure. Its features are, An absorption control structure (11) extending along a preset direction is provided on the ridge waveguide (7). The absorption control structure (11) is used to selectively lose the laser mode in the edge region of the ridge waveguide (7) during laser oscillation. The absorption regulation structure (11) is composed of a local regulation region formed by processing and a material with absorption properties set in the region.

2. The optical mode self-stabilizing single transverse mode semiconductor laser according to claim 1, characterized in that, The local control region is a recessed structure formed by etching, which extends along a direction perpendicular to the laser plane.

3. The optical mode self-stabilizing single transverse mode semiconductor laser according to claim 2, characterized in that, The recessed structure is arranged on both sides of the ridge waveguide (7) along the length of the laser cavity. The recessed structure extends at least partially into the internal region of the waveguide structure. The semiconductor material filled inside the recessed structure is an epitaxial material that matches the lattice constant of the sidewall material of the recessed structure.

4. The optical mode self-stabilizing single transverse mode semiconductor laser according to claim 3, characterized in that, Semiconductor materials filling the recessed structure form absorption centers through doping or defect state modulation, which are used to absorb the light field energy corresponding to higher-order transverse modes under laser operating conditions.

5. The optical mode self-stabilizing single transverse mode semiconductor laser according to any one of claims 1-4, characterized in that, The electrode structure is configured to form a current injection opening at the top of the ridge waveguide (7).

6. A method for fabricating a semiconductor laser, characterized in that, This method is used to prepare the optical mode self-stabilized single transverse mode semiconductor laser as described in claim 1. The method includes the following steps: Waveguide structures and active layers are epitaxially grown on a substrate; A ridge waveguide is formed on top of the waveguide structure using photolithography and etching processes. Photolithography is performed in the lateral region of the ridge waveguide to define a local control region, and an etching process is used to form a recessed structure extending in a direction perpendicular to the laser plane in the defined region. The wafer with the recessed structure is placed in an epitaxial growth device, and a semiconductor material with a lattice constant matching the sidewall material of the recessed structure is grown inside the recessed structure. By doping or defect state modulation, the material is made to have the characteristic of absorbing the light field energy corresponding to higher-order lateral modes. The wafer surface is wet-processed to remove residual material, and an insulating layer covering the entire surface is grown on it, forming an opening in the insulating layer at the top region of the ridge waveguide. A metal layer is formed above the insulating layer and the ohmic contact layer, such that the metal layer only contacts the ohmic contact layer at the opening of the insulating layer at the top of the ridge waveguide; A back electrode is formed on the back side of the substrate to complete the fabrication of the semiconductor laser.

7. The method for fabricating a semiconductor laser according to claim 6, characterized in that, The recessed structure is formed by a dry etching process, which includes an etching process using chlorine-based or fluorine-based gases as the etching reaction gases.

8. The method for fabricating a semiconductor laser according to claim 6, characterized in that, The semiconductor material grown inside the recessed structure is one or more selected from GaAs, AlGaAs, GaInP, and AlInP.

9. The method for fabricating a semiconductor laser according to claim 8, characterized in that, In the process of enabling a material to absorb the energy of a light field corresponding to a higher-order transverse mode through doping or defect state modulation, doping elements or defect states are introduced into the intrinsic material system of the semiconductor material to form absorption centers. The doping elements include one or more of C, Cr, Mg, B, and Zn.

10. The method for fabricating a semiconductor laser according to claim 6, characterized in that, The insulating layer is formed using a dielectric thin film growth process, and the dielectric thin film material includes one or more of SiO2, SiN, TiO, or Al2O3.

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