Laser structure preparation method and laser structure

Abstract

The present application relates to a method for preparing a laser structure and a laser structure, the method comprising: providing an epitaxial structure, the epitaxial structure comprising a substrate, a first doped medium layer, a multi-quantum well active layer and a ridge-shaped doped medium layer stacked in sequence; forming a grating structure on the ridge-shaped doped medium layer and forming a reflecting surface on the end face of the grating structure, the reflecting surface and the grating structure are defined by a photolithography mask in the same step, and the mask is selectively protected during the semiconductor etching process, such as by using a medium layer with different etching rates, so as to ensure that the relative position of the reflecting surface and the grating structure is not changed, so that the light reflected from the reflecting surface back to the laser cavity has a preset phase defined by the design, thereby improving the performance and stability of the laser operation, reducing the complexity of the production process and the manufacturing cost, and improving the yield and reliability.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor laser manufacturing, and in particular to a laser structure preparation method and a laser structure. Background Art

[0002] Distributed feedback semiconductor lasers are widely deployed in optical communication systems due to their advantages such as dynamic single mode, small size, high integration capability and reliable light source. The basic elements of a laser include three parts: gain medium, cavity with feedback mechanism and energy input. There are two feedback mechanisms for distributed feedback lasers (DFB): one is periodic refractive index modulation; the other is periodic gain (loss) modulation.

[0003] How to improve the yield and reliability of distributed feedback semiconductor lasers and reduce their manufacturing costs is one of the technical problems that relevant technicians urgently need to solve. Summary of the invention

[0004] Based on this, it is necessary to provide a laser structure preparation method and a laser structure to address the problems in the above-mentioned background technology, so as to effectively improve the performance and stability of semiconductor lasers, reduce the complexity of the production process and the manufacturing cost, and improve their yield and reliability.

[0005] To achieve the above-mentioned purpose and other related purposes, one aspect of the present application provides a method for preparing a laser structure, comprising: providing an epitaxial structure, the epitaxial structure comprising a substrate, a first doped medium layer, a multi-quantum well active layer and a ridge-shaped doped medium layer stacked in sequence; forming a grating structure on the ridge-shaped doped medium layer and forming a reflecting surface at one end of the grating structure, the grating structure comprising a plurality of grating grooves periodically distributed along the waveguide direction of the laser and a preset conductive region defined by each of the grating grooves, a light-transmitting insulating layer at least covering the sidewalls of the grating grooves is formed in the grating grooves; the light reflected back to the laser cavity by the reflecting surface has a preset phase; forming a top surface electrode layer, the top surface electrode layer at least forms an ohmic electrical contact with the top surface of the preset conductive region, so that carriers injected through the top surface electrode layer flow through the preset conductive region and the ridge-shaped doped medium layer below the grating grooves in sequence and then diffuse laterally to the multi-quantum well active layer, forming a carrier distribution region for providing pumping.

[0006] In the laser structure preparation method in the above embodiment, the process involved can be implemented on a laser using a surface-etched grating, and the proposed process can achieve the following functions: the distance between the reflection surface at one end of the grating structure and the reflection grating can be determined by design, and the accuracy is guaranteed by photolithography during manufacturing, so that the uncertainty of the light phase reflected back to the laser cavity is minimized. Since the reflection surface in the present application is formed in the process of preparing the grating structure, the process steps introduced by adding the reflection surface are effectively reduced, the manufacturing cost of the laser structure is reduced, and the yield and reliability of the prepared laser are improved. A grating structure including a plurality of grating grooves periodically distributed along the waveguide direction of the laser and a preset conductive area defined by each grating groove is formed on the ridge-shaped doped medium layer. The grating groove is an electrical insulator, which limits the flow area of ​​the current injected by the top electrode layer. When the distance between the bottom of the grating groove and the multi-quantum well active layer is small, the diffusion of the injected current at the bottom of the grating groove is limited, which will cause the carrier density to fluctuate periodically with the grating groove in the direction of the laser cavity, resulting in a certain degree of gain modulation. Since the phase of gain coupling and the phase of refractive index coupling in the present application are consistent and will not cancel each other out, the gain modulation intensity and the refractive index modulation intensity can be adjusted by setting the shape, size and number of grating grooves, which effectively improves the performance of the laser. The reflective surface can be used to realize asymmetric mirror feedback of the laser to break the degenerate mode and realize stable single-mode output of the laser. Since the reflective surface in the present application is formed during the preparation of the grating structure, the process steps introduced by adding the reflective surface are effectively reduced, the manufacturing cost of the laser structure is reduced, and the yield and reliability of the prepared laser structure are improved.

[0007] In one embodiment, the step of forming a grating structure on the ridge-shaped doped dielectric layer and forming a reflective surface at one end of the grating structure includes: forming a first mask layer on the upper surface of the ridge-shaped doped dielectric layer, the first mask layer including a first opening pattern and a second opening pattern formed by photolithography and removing a portion of the first mask layer, the first opening pattern being used to define the position and shape of the grating groove, and the second opening pattern being used to define the position and shape of the reflective surface with a preset phase; forming a second mask layer, the second mask layer at least covering the second opening pattern and exposing the first opening pattern The method comprises the steps of: removing a portion of the first mask layer and a portion of the ridge-shaped doped dielectric layer to form the grating grooves; forming a light-transmitting insulating material layer, wherein the light-transmitting insulating material layer fills the grating grooves and covers the upper surface of the second mask layer; removing a portion of the light-transmitting insulating material layer, a portion of the second mask layer, a portion of the ridge-shaped doped dielectric layer, a portion of the multi-quantum well active layer and a portion of the first doped dielectric layer to form the reflecting surface; removing the light-transmitting insulating material layer located on the upper surface of the grating grooves to form the grating structure, and the retained light-transmitting insulating material layer constitutes the light-transmitting insulating layer.

[0008] In the laser structure preparation method in the above embodiment, a first opening pattern for defining a plurality of grating grooves and a second opening pattern for defining a reflecting surface are simultaneously set through a first mask layer, thereby effectively reducing the process steps, reducing the process complexity and implementation cost, and improving the accuracy of the distance between the reflecting surface and the end of the grating structure, so that the phase of the light reflected from the reflecting surface back to the laser cavity is determined, thereby improving the performance and stability of the laser operation.

[0009] In one embodiment, the step of forming a grating structure on the ridge-shaped doped dielectric layer and forming a reflective surface at one end of the grating structure includes: forming a first mask layer on the upper surface of the ridge-shaped doped dielectric layer, the first mask layer including a first opening pattern and a second opening pattern formed by photolithography and removing a portion of the first mask layer, the first opening pattern being used to define the position and shape of the grating groove, and the second opening pattern being used to define the position and shape of the reflective surface; forming a second mask layer, the second mask layer at least covering the second opening pattern and exposing the first opening pattern and a portion of the upper surface of the ridge-shaped doped dielectric layer; removing a portion of the first mask layer and a portion of the ridge-shaped doped dielectric layer to form the grating groove ; forming a light-transmitting insulating material layer, the light-transmitting insulating material layer fills the grating grooves and covers the upper surface of the second mask layer; removing the light-transmitting insulating material layer located on the upper surface of the grating grooves to form the grating structure, and the retained light-transmitting insulating material layer constitutes the light-transmitting insulating layer; forming a top surface electrode layer, the top surface electrode layer at least covers the upper surface of the preset conductive area and forms an ohmic electrical contact with the top surface of the preset conductive area; forming a third mask layer, the third mask layer at least covers the upper surface of the top surface electrode layer; removing part of the light-transmitting insulating material layer, part of the second mask layer, part of the ridge-shaped doped dielectric layer, part of the multi-quantum well active layer and part of the first doped dielectric layer to form the reflecting surface.

[0010] In the laser structure preparation method in the above embodiment, a first opening pattern for defining a plurality of grating grooves and a second opening pattern for defining a reflecting surface are simultaneously set through a first mask layer, thereby effectively reducing the process steps, reducing the process complexity and implementation cost, and improving the accuracy of the distance between the reflecting surface and the end of the grating structure, so that the phase of the light reflected from the reflecting surface back to the laser cavity is determined, thereby improving the performance and stability of the laser operation.

[0011] In one embodiment, after forming the light-transmitting insulating material layer, the method further includes: removing the light-transmitting insulating material layer located on the upper surface of the grating groove to form the grating structure, and the retained light-transmitting insulating material layer constitutes the light-transmitting insulating layer; forming a top surface electrode layer, wherein the top surface electrode layer at least covers the upper surface of the preset conductive area and forms an ohmic electrical contact with the top surface of the preset conductive area; forming a third mask layer, wherein the third mask layer at least covers the upper surface of the top surface electrode layer; and removing a portion of the light-transmitting insulating material layer, a portion of the second mask layer, a portion of the ridge-shaped doped dielectric layer, a portion of the multi-quantum well active layer, and a portion of the first doped dielectric layer to form the reflective surface.

[0012] In one embodiment, the second mask layer and the first mask layer have different etching rates, and the second mask layer is used to protect the second opening pattern to avoid adverse effects on the shape of the second opening pattern during etching of the grating grooves.

[0013] In one embodiment, the steps of forming a grating structure on the ridge-shaped doped dielectric layer and forming a reflective surface at one end of the grating structure include: forming a first mask layer on the upper surface of the ridge-shaped doped dielectric layer, the first mask layer including a first opening pattern and a second opening pattern formed by photolithography and removing a portion of the first mask layer, the first opening pattern being used to define the position and shape of the grating groove, and the second opening pattern being used to define the position and shape of the reflective surface with a preset phase; forming a fourth mask layer, the fourth mask layer at least covering the first opening pattern and exposing the second opening pattern; removing a portion of the ridge-shaped doped dielectric layer, a portion of the multi-quantum well active layer and a portion of the first doped dielectric layer to form the reflective surface; removing the fourth mask layer to expose the first opening pattern, etching and removing a portion of the first mask layer and a portion of the ridge-shaped doped dielectric layer based on the first opening pattern to form the grating groove; and forming a light-transmitting insulating layer at least in the grating groove to form the grating structure.

[0014] In one embodiment, the fourth mask layer and the first mask layer have different etching rates.

[0015] In one embodiment, before forming a grating structure on the ridge-shaped doped dielectric layer and forming a reflective surface at one end of the grating structure, the method further includes: forming an electrical contact layer on top of the ridge-shaped doped dielectric layer to form the top surface electrode layer on the upper surface of the electrical contact layer, and the electrical contact layer can make the top surface electrode layer form an effective electrical connection with the preset conductive region. Forming the electrical contact layer on top of the ridge-shaped doped dielectric layer can effectively reduce the volume of the prepared laser structure.

[0016] In one embodiment, before forming the grating structure and the reflecting surface, or between forming the grating structure and the reflecting surface, or after forming the grating structure and the reflecting surface, it also includes: performing at least one laser waveguide definition process on the resulting structure to further improve the performance of the laser while reducing the complexity of the production process.

[0017] In one embodiment, after forming the reflective surface, the method further includes: forming a reflective film on the reflective surface.

[0018] In one embodiment, the material forming the reflective film includes a high-reflective material and / or an anti-reflective material, so as to utilize asymmetric mirror feedback to break the degenerate mode and achieve stable single-mode output of the laser.

[0019] Another aspect of the present application provides a laser structure, comprising: a laser structure prepared by any of the laser structure preparation methods described in the embodiments of the present application. A grating structure including a plurality of grating grooves periodically distributed along the waveguide direction of the laser and a preset conductive area defined by each grating groove is formed on a ridge-shaped doped medium layer. The grating groove is an electrical insulator, which limits the flow area of ​​the injected current. When the distance between the bottom of the grating groove and the multi-quantum well active layer is small, the diffusion of the injected current at the bottom of the grating groove is limited, which will cause the carrier density to fluctuate periodically with the grating groove in the direction of the laser cavity, resulting in a certain degree of gain modulation. Since the phase of the gain coupling in the present application is consistent with the phase of the refractive index coupling and will not cancel each other, the gain modulation intensity and the refractive index modulation intensity can be adjusted by setting the shape, size and number of the grating grooves, effectively improving the performance of the laser. The asymmetric mirror feedback of the laser can be realized by using the reflective surface to break the degenerate mode and achieve stable single-mode output of the laser. Since the reflective surface in the present application is formed during the preparation of the grating structure, the process steps introduced by adding the reflective surface are effectively reduced, the manufacturing cost of the laser structure is reduced, and the yield and reliability of the prepared laser structure are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to better describe and illustrate the embodiments and / or examples of those applications disclosed herein, reference may be made to one or more drawings. The additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the embodiments and / or examples currently described, and the best modes of these applications currently understood.

[0021] Figure 1 Shown is a schematic flow chart of a laser structure preparation method provided in an embodiment of the present application;

[0022] Figure 2 Shown is a schematic flow chart of a laser structure preparation method provided in another embodiment of the present application;

[0023] Figure 3a Shown is a schematic flow chart of a laser structure preparation method provided in yet another embodiment of the present application;

[0024] Figure 3b Shown is a schematic flow chart of a laser structure preparation method provided in another embodiment of the present application;

[0025] Figure 4-Figure 13 Shown are schematic cross-sectional structures obtained in different steps in the embodiments of the present application;

[0026] Fig.14Shown is a schematic diagram of a refractive index coupling intensity curve of a laser structure in one embodiment of the present application;

[0027] Figure 15-16 Shown is a schematic diagram of a modulation curve of the injected current amplitude versus carrier distribution in the laser structure in different embodiments of the present application.

[0028] Description of reference numerals:

[0029] 10. first doped medium layer; 11. functional element; 20. multi-quantum well active layer;

[0030] 30, ridge-shaped doped dielectric layer; 31, reflecting surface; 100, substrate; 1000, epitaxial structure;

[0031] 40. grating structure; 41. grating groove; 42. preset conductive area; 50. top electrode layer;

[0032] 70, electrical contact layer; 80, first mask layer; 81, first opening pattern; 82, second opening pattern;

[0033] 90, second mask layer; 1011, light-transmitting insulating material layer; 101, light-transmitting insulating layer; 102, third mask layer. DETAILED DESCRIPTION

[0034] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0036] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as a second element, component, region, layer or part.

[0037] Spatially relative terms such as "under," "below," "below," "under," "above," "above," etc., may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, the spatially relative terms are intended to include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "on" the other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0038] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0039] Embodiments of the application are described herein with reference to cross-sectional views that are schematic diagrams of ideal embodiments (and intermediate structures) of the application. Thus, variations from the shapes shown due to, for example, manufacturing techniques and / or tolerances can be expected. Therefore, embodiments of the application should not be limited to the specific shapes of the zones shown herein, but rather include shape deviations due to, for example, manufacturing, and the zones shown in the figures are schematic in nature, and their shapes are not intended to display the actual shapes of the zones of the device and are not intended to limit the scope of the application.

[0040] The “light-transmitting” mentioned in the present application refers to a transmittance of light emitted by a laser being greater than or equal to 75%.

[0041] Distributed feedback lasers use a periodic grating structure along the longitudinal direction of the active cavity to achieve periodic modulation of the effective refractive index of the active waveguide. Refractive index modulation produces constructive interference of wavelengths through the real part, imaginary part or complex part, thereby selecting the laser wavelength near the Bragg wavelength. The Bragg wavelength is λ B =2Λneff / m, where Λ is the grating period, neff is the effective refractive index of the guided mode, and m is the grating order. The basic elements of a laser are three parts: a gain medium, a cavity with a feedback mechanism, and an energy input. There are two ways to implement feedback mechanisms in distributed feedback lasers: one is to form a periodic grating structure along the active medium in the longitudinal direction, and the other is to use the effective refractive index of the active waveguide to introduce periodic modulation. This periodic modulation achieves constructive interference within a specific wavelength range, with the center being the Bragg wavelength. There are two degenerate resonant modes, symmetrically distributed on both sides of the Bragg wavelength. By adding additional structures such as reflective surfaces to the distributed feedback laser, stable single-mode output of the distributed feedback laser can be achieved. As we all know, a continuous grating will have two longitudinal modes at equidistant positions on both sides of the Bragg wavelength. In order to achieve single-mode operation and increase the output power of the laser front end, the rear end of the laser cavity is usually coated with a high-reflection film and the front end is coated with an anti-reflection film. The phase reflected back to the laser cavity by the high-reflection film directly affects the performance of the laser. The accurate control of the phase (i.e., the position of the high-reflection film relative to the grating) is also very challenging. Failure to control the phase will lead to problems such as high-cost testing and screening processes and low yields.

[0042] The present application aims to provide a method for preparing a laser structure and a laser structure, wherein the spacing between the reflection surface and the end of the grating structure is determined by the design and lithography capabilities, so that the phase of the light reflected from the reflection surface back to the laser cavity is determined, thereby improving the performance and stability of the laser operation, reducing the complexity of the production process and the manufacturing cost, and improving its yield and reliability.

[0043] See also Figure 1-Figure 16It should be noted that the illustrations provided in this embodiment are only schematic illustrations of the basic concept of the present application. Although the illustrations only show components related to the present application and are not drawn according to the number, shape and size of components in actual implementation, the type, quantity and proportion of each component in actual implementation may be changed arbitrarily, and the component layout may also be more complicated.

[0044] See also Figure 1 In one embodiment of the present application, a method for preparing a laser structure is provided, comprising the following steps:

[0045] Step S110: providing an epitaxial structure, wherein the epitaxial structure comprises a substrate, a first doped medium layer, a multi-quantum well active layer and a ridge-shaped doped medium layer stacked in sequence;

[0046] Step S120: forming a grating structure on the ridge-shaped doped dielectric layer and forming a reflecting surface at one end of the grating structure, wherein the grating structure comprises a plurality of grating grooves periodically distributed along the waveguide direction of the laser and a preset conductive region defined by each of the grating grooves, wherein a light-transmitting insulating layer at least covering the sidewalls of the grating grooves is formed in the grating grooves; and the light reflected back to the laser cavity by the reflecting surface has a preset phase;

[0047] Step S130: forming a top surface electrode layer, wherein the top surface electrode layer forms an ohmic electrical contact with at least the top surface of the preset conductive region, so that the carriers injected through the top surface electrode layer flow sequentially through the preset conductive region, the ridge-shaped doped medium layer under the grating groove, and then diffuse laterally to the multi-quantum well active layer, thereby forming a carrier distribution region for providing pumping.

[0048] For details, please continue to see Figure 1First, a grating structure including a plurality of grating grooves evenly spaced and distributed along the waveguide direction of the laser and a preset conductive area defined by each grating groove is formed on the ridge-shaped doped medium layer; since the grating groove is an electrical insulator, it limits the flow area of ​​the injected current; when the distance between the bottom of the grating groove and the multi-quantum well active layer is small, the diffusion of the injected current at the bottom of the grating groove is limited, which will cause the carrier density to fluctuate periodically along the grating groove in the direction of the laser cavity, resulting in a certain degree of gain modulation. Since the phase of the gain coupling in the present application is consistent with the phase of the refractive index coupling and will not cancel each other, the gain modulation intensity and the refractive index modulation intensity can be adjusted by setting the shape, size and number of the grating grooves, which effectively improves the performance of the laser. The reflective surface can be used to realize the asymmetric mirror feedback of the laser to break the degenerate mode and realize the stable single-mode output of the laser. Since the reflective surface in the present application is formed in the process of preparing the grating structure, the process steps introduced by adding the reflective surface are effectively reduced, the manufacturing cost of the laser structure is reduced, and the yield and reliability of the prepared laser structure are improved. In this embodiment, the carriers in the carrier distribution region may be arranged to be uniformly distributed under conditions of different injection currents.

[0049] Since the grating structure includes a plurality of grating grooves evenly spaced and distributed along the waveguide direction of the laser and a preset conductive area defined by each grating groove, that is, the distribution of the grating grooves is periodic, so that the grating duty ratio of the grating structure is associated with the gain modulation intensity of the ridge laser structure, wherein the grating duty ratio is the ratio of the area of ​​the positive projection of the preset conductive area on the upper surface of the first doped medium layer to the grating period; the grating order of the grating structure is associated with the refractive index modulation intensity of the ridge laser structure. By establishing a corresponding relationship between the grating duty ratio of the grating structure and the gain modulation intensity of the ridge laser structure, the gain modulation intensity of the ridge laser structure can be adjusted by setting the grating duty ratio of the grating structure. By establishing a corresponding relationship between the grating order of the grating structure and the refractive index modulation intensity of the ridge laser structure, the refractive index modulation intensity of the ridge laser structure can be adjusted by setting the grating order of the grating structure. Thus, the degree of freedom in preparing the gain modulation intensity and / or refractive index modulation intensity of the laser is increased.

[0050] See also Figure 2 In one embodiment of the present application, a grating structure is formed on the ridge-shaped doped dielectric layer and a reflective surface is formed on one end face of the formed grating structure. The reflective surface and the grating structure are shaped by the same photolithography pattern. However, the manufacture of other functional elements can be inserted between the etching of the reflective surface and the grating structure, such as the top surface electrode layer in this embodiment. The step of forming a grating structure on the ridge-shaped doped dielectric layer and forming a reflective surface at one end of the grating structure includes the following steps:

[0051] Step S121: forming a first mask layer on the upper surface of the ridge-shaped doped dielectric layer, the first mask layer comprising a first opening pattern and a second opening pattern formed by photolithography and removing a portion of the first mask layer, the first opening pattern being used to define the position and shape of a plurality of grating grooves, and the second opening pattern being used to define the position and shape of a reflective surface;

[0052] Step S122: forming a second mask layer, wherein the second mask layer at least covers the second opening pattern and exposes the first opening pattern;

[0053] Step S123: etching and removing a portion of the first mask layer and a portion of the ridge-shaped doped dielectric layer based on the first opening pattern to form the grating groove;

[0054] Step S124: forming a light-transmitting insulating material layer, wherein the light-transmitting insulating material layer fills the grating grooves and covers the upper surface of the second mask layer;

[0055] Step S125: removing part of the light-transmitting insulating material layer, part of the second mask layer, part of the ridge-shaped doped dielectric layer, part of the multi-quantum well active layer and part of the first doped dielectric layer to form the reflective surface;

[0056] Step S126: removing the light-transmitting insulating material layer located on the upper surface of the grating groove to form the grating structure, and the remaining light-transmitting insulating material layer constitutes a light-transmitting insulating layer.

[0057] In the laser structure preparation method in the above embodiment, a reflective surface structure is first formed on the ridge-shaped doped dielectric layer, and then a grating structure is formed. The reflective surface and the grating structure are shaped by the same photolithography pattern, so that the distance between the reflective surface and the grating structure is determined by the design, and the manufacturing uncertainty is minimized. For example, a reflective film can be deposited on the reflective surface. The material forming the reflective film can include a high-reflective material and / or an anti-reflective material, so that a high-reflective film and / or an anti-reflective film can be deposited on the reflective surface, and the degenerate mode is broken by asymmetric mirror feedback to achieve stable single-mode output of the laser.

[0058] As an example, see Figure 3a The step of forming a grating structure on the ridge-shaped doped medium layer and forming a reflective surface on the end face of the grating structure comprises the following steps:

[0059] Step S121: forming a first mask layer on the upper surface of the ridge-shaped doped dielectric layer, the first mask layer comprising a first opening pattern and a second opening pattern formed by photolithography and removing a portion of the first mask layer, the first opening pattern being used to define the position and shape of a plurality of grating grooves, and the second opening pattern being used to define the position and shape of a reflective surface;

[0060] Step S1222: forming a fourth mask layer, wherein the fourth mask layer at least covers the first opening pattern and exposes the second opening pattern;

[0061] Step S1223: removing part of the ridge-shaped doped medium layer, part of the multi-quantum well active layer and part of the first doped medium layer to form the reflective surface;

[0062] Step S1224: removing the fourth mask layer to expose the first opening pattern, etching and removing a portion of the first mask layer and a portion of the ridge-shaped doped dielectric layer based on the first opening pattern to form the grating groove;

[0063] Step S1225: forming a light-transmitting insulating layer at least in the grating grooves to form the grating structure.

[0064] As an example, the first mask layer in step S121 may include a hard mask layer. The hard mask layer may be a single-layer structure or a multi-layer stacked structure, and its material includes but is not limited to silicon nitride.

[0065] As an example, in step S122 , a deposition process may be used to form a second mask layer, and the second mask layer at least covers the second opening pattern and exposes the first opening pattern and a portion of the upper surface of the ridge-shaped doped dielectric layer.

[0066] As an example, in step S123, an etching process may be used to remove part of the first mask layer and part of the ridge-shaped doped dielectric layer to form the grating groove.

[0067] As an example, the material used to prepare the light-transmitting insulating material layer in step S124 may include at least one of silicon nitride, silicon dioxide, silicon oxynitride, benzocyclobutene, polyimide and spin-on-glass.

[0068] As an example, in step S125, an etching process may be used to remove part of the light-transmitting insulating material layer, part of the second mask layer, part of the ridge-shaped doped dielectric layer, part of the multi-quantum well active layer and part of the first doped dielectric layer to form the reflective surface.

[0069] As an example, in step S126 , an etching process may be used to remove the light-transmitting insulating material layer located on the upper surface of the grating groove to form the grating structure, and the remaining light-transmitting insulating material layer constitutes a light-transmitting insulating layer.

[0070] For details, please continue to see Figure 2The first mask layer is used to simultaneously set a first opening pattern for defining a plurality of grating grooves and a second opening pattern for defining a reflective surface, which effectively reduces the process steps, reduces the process complexity and implementation cost, and improves the accuracy of the distance between the reflective surface and the end of the grating structure, so that the phase of the light reflected from the reflective surface back to the laser cavity is determined, thereby improving the performance and stability of the laser operation. Please continue to read Figure 2 The etching rates of the second mask layer and the first mask layer are different. The second mask layer is used to protect the second opening pattern to avoid adverse effects on the shape of the second opening pattern during etching of the grating groove or the reflective surface.

[0071] As an example, before forming a grating structure on the ridge-shaped doped dielectric layer and forming a reflective surface at one end of the grating structure, it also includes: performing an ion implantation process on the ridge-shaped doped dielectric layer, forming an electrical contact layer on the top of the ridge-shaped doped dielectric layer, and forming the top surface electrode layer on the upper surface of the electrical contact layer. The electrical contact layer can make the top surface electrode layer form an effective electrical connection with the preset conductive region. The electrical contact layer is formed on the top of the ridge-shaped doped dielectric layer by the ion implantation process, which can effectively reduce the volume of the prepared laser structure. For example, an ion implantation process can be performed from the top of the preset conductive region to the preset conductive region to form a conductive contact layer, so that the doping concentration of the conductive contact layer is greater than the doping concentration of the preset conductive region below it, so that the conductive performance of the conductive contact layer is better than the conductive performance of the preset conductive region below it, so that the top surface electrode layer can inject current downward through the conductive contact layer.

[0072] As an example, see Figure 3b In one embodiment of the present application, the steps of forming a grating structure on the ridge-shaped doped dielectric layer and forming a top electrode layer on the top of the grating structure, and forming a reflective surface on the rear end surface thereof, include the following steps:

[0073] Step S121: forming a first mask layer on the upper surface of the ridge-shaped doped dielectric layer, the first mask layer comprising a first opening pattern and a second opening pattern formed by single-exposure photolithography and removing a portion of the first mask layer, the first opening pattern being used to define the position and shape of a plurality of grating grooves, and the second opening pattern being used to define the position and shape of a reflective surface;

[0074] Step S122: forming a second mask layer, wherein the second mask layer at least covers the second opening pattern and exposes the first opening pattern;

[0075] Step S123: removing part of the first mask layer and part of the ridge-shaped doped dielectric layer to form the grating groove;

[0076] Step S124: forming a light-transmitting insulating material layer, wherein the light-transmitting insulating material layer fills the grating grooves and covers the upper surface of the second mask layer;

[0077] Step S127: removing the light-transmitting insulating material layer located on the upper surface of the grating groove to form the grating structure, and the remaining light-transmitting insulating material layer constitutes a light-transmitting insulating layer;

[0078] Step S128: forming a top surface electrode layer, wherein the top surface electrode layer at least covers the upper surface of the preset conductive region and forms an ohmic electrical contact with the top surface of the preset conductive region;

[0079] Step S129: forming a third mask layer, wherein the third mask layer at least covers the upper surface of the top electrode layer;

[0080] Step S1210: removing part of the light-transmitting insulating material layer, part of the second mask layer, part of the ridge-shaped doped dielectric layer, part of the multi-quantum well active layer and part of the first doped dielectric layer to form the reflective surface.

[0081] Please continue to refer to FIG3. By simultaneously setting a first opening pattern for defining a plurality of grating grooves and a second opening pattern for defining a reflection surface through the first mask layer, the process steps are effectively reduced, the process complexity and implementation cost are reduced, and the accuracy of the distance between the reflection surface and the end of the grating structure is improved, so that the phase of the light reflected from the reflection surface back to the laser cavity is determined, and the performance and stability of the laser operation are improved. The etching rate of the second mask layer and the first mask layer can be set to be different, and the second mask layer is used to protect the second opening pattern to avoid adverse effects on the shape of the second opening pattern during the etching of the grating grooves.

[0082] As an example, see Figure 4-Figure 9The epitaxial structure 1000 includes a substrate 100, a first doped dielectric layer 10, a multi-quantum well active layer 20 and a ridge doped dielectric layer 30 stacked in sequence; an ion implantation process is performed on the ridge doped dielectric layer 30 to form an electrical contact layer 70 on the top of the ridge doped dielectric layer 30, so as to form a top surface electrode layer 50 on the upper surface of the electrical contact layer 70; a first mask layer 80 is formed on the upper surface of the ridge doped dielectric layer 30, and the first mask layer 80 includes a first opening pattern and a second opening pattern formed by single-exposure lithography and removing a portion of the first mask layer 80, the first opening pattern is used to define the position and shape of a plurality of grating grooves 41, and the second opening pattern is used to define the position and shape of the reflective surface 31; a second mask layer 90 is formed, and the second mask layer 90 to The second opening pattern is less covered and the first opening pattern and a portion of the upper surface of the ridge-shaped doped dielectric layer 30 are exposed; a portion of the first mask layer 80 and a portion of the ridge-shaped doped dielectric layer 30 are removed to form a grating groove 41; a light-transmitting insulating material layer 1011 is formed, and the light-transmitting insulating material layer 1011 fills each grating groove 41 and covers the upper surface of the second mask layer 90; a portion of the light-transmitting insulating material layer 1011, a portion of the second mask layer 90, a portion of the ridge-shaped doped dielectric layer 30, a portion of the multi-quantum well active layer 20 and a portion of the first doped dielectric layer 10 are removed to form a reflecting surface 31; the light-transmitting insulating material layer 1011 located on the upper surface of the grating groove 41 is removed to form a grating structure 40, and the retained light-transmitting insulating material layer 1011 constitutes the light-transmitting insulating layer 101. By simultaneously setting a first opening pattern for defining a plurality of grating grooves 41 and a second opening pattern for defining the reflecting surface 31 through the first mask layer 80, the process steps are effectively reduced, the process complexity and the implementation cost are reduced, and the accuracy of the distance between the reflecting surface 31 and the end of the grating structure 40 is improved, so that the phase of the light reflected from the reflecting surface 31 back to the laser cavity is determined, thereby improving the performance and stability of the laser operation.

[0083] As an example, see Figure 4-Figure 9 , Figure 10-12The epitaxial structure 1000 includes a substrate 100, a first doped dielectric layer 10, a multi-quantum well active layer 20 and a ridge-shaped doped dielectric layer 30 which are stacked in sequence; an ion implantation process is performed on the ridge-shaped doped dielectric layer 30 to form a heavily doped electrical contact layer 70 on the top of the ridge-shaped doped dielectric layer 30, so that the doping concentration of the electrical contact layer 70 is greater than the doping concentration of the preset conductive region 42 thereunder, so that the conductive performance of the electrical contact layer 70 is better than the conductive performance of the preset conductive region 42 thereunder; and a highly doped electrical contact layer 70 is formed on the upper surface of the electrical contact layer 70. A top electrode layer 50 is formed so that the top electrode layer 50 can inject current downward through the electrical contact layer 70; a first mask layer 80 is formed on the upper surface of the ridge-shaped doped dielectric layer 30, and the first mask layer 80 includes a first opening pattern 81 and a second opening pattern 82 formed by single-exposure photolithography and removing a portion of the first mask layer 80, the first opening pattern 81 is used to define the position and shape of the plurality of grating grooves 41, and the second opening pattern 82 is used to define the position and shape of the reflection surface 31; a second mask layer 90 is formed, and the second mask layer 90 is formed. The layer 90 at least covers the second opening pattern and exposes the first opening pattern 81 and a portion of the upper surface of the ridge-shaped doped dielectric layer 30; removes a portion of the first mask layer 80 and a portion of the ridge-shaped doped dielectric layer 30 to form a grating groove 41; forms a light-transmitting insulating material layer 1011, the light-transmitting insulating material layer 1011 fills each grating groove 41 and covers the upper surface of the second mask layer 90; removes the light-transmitting insulating material layer 1011 located on the upper surface of the grating groove 41 to form a grating structure 40, and the remaining light-transmitting insulating material layer 1011 constitutes a light-transmitting insulating layer 101; forms a top electrode layer 50, which at least covers the upper surface of the preset conductive region 42 and forms an ohmic electrical contact with the top surface of the preset conductive region 42; forms a third mask layer 102, which at least covers the upper surface of the top electrode layer 50; removes part of the light-transmitting insulating material layer 1011, part of the second mask layer 90, part of the ridge-shaped doped dielectric layer 30, part of the multi-quantum well active layer 20 and the first doped dielectric layer 10 to form a reflective surface 31. The first mask layer 80 is used to simultaneously set a first opening pattern 81 for defining a plurality of grating grooves 41 and a second opening pattern 82 for defining the reflective surface 31, which effectively reduces the process steps, reduces the process complexity and implementation cost, and improves the accuracy of the distance between the reflective surface 31 and the end of the grating structure 40, so that the phase of the light reflected from the reflective surface 31 back to the laser cavity is determined, and the performance and stability of the laser operation are improved. The etching rates of the second mask layer 90 and the first mask layer 80 may be different, and the second mask layer 90 may be used to protect the second opening pattern 82 to avoid adverse effects on the shape of the second opening pattern 82 during the etching of the grating groove 41 .

[0084] As an example, see Figure 4-Figure 12, before forming the grating structure 40 and the reflecting surface 31, or between forming the grating structure 40 and the reflecting surface 31, or after forming the grating structure 40 and the reflecting surface 31, it also includes: performing at least one laser waveguide definition process on the resulting structure to further improve the performance of the laser while reducing the complexity of the production process.

[0085] As an example, see Figure 4-Figure 12 , the doping type of the first doped dielectric layer 10 is P type, and the doping type of the ridge-shaped doped dielectric layer 30 is N type; or the doping type of the first doped dielectric layer 10 is N type, and the doping type of the ridge-shaped doped dielectric layer 30 is P type.

[0086] As an example, see Figure 4-Figure 12 The light-transmitting insulating layer 101 includes a dielectric material and / or a polymer material, and ensures the light transmittance of the grating groove 41 under the premise of ensuring the insulation of the grating groove 41. The light-transmitting insulating layer may include any one of silicon nitride, silicon dioxide, silicon oxynitride, benzocyclobutene, polyimide and spin-on glass, etc., but is not limited to these materials. When the grating groove is filled, a small amount of air, photoresist or metal may remain, which will not have a serious impact on the grating function. Therefore, the light-transmitting insulating layer may include at least one of a gap, residual photoresist and residual metal, which can increase the insulation performance of the light-transmitting insulating layer.

[0087] As an example, see Figure 4-Figure 12 The material forming the reflection surface 31 includes a high reflection film and / or an anti-reflection film, so as to utilize asymmetric mirror feedback to break the degenerate mode and realize stable single-mode output of the laser.

[0088] As an example, see Fig.13 The present application provides a laser structure, which is prepared by the laser structure preparation method described in any of the embodiments of the present application; the structure includes a substrate 100, a first doped medium layer 10, a multi-quantum well active layer 20, a ridge doped medium layer 30, and a grating structure 40 formed on the ridge doped medium layer 30 and a top surface electrode layer 50 located on the top surface of the grating structure 40; the grating structure 40 includes a plurality of grating grooves 41 periodically distributed along the waveguide direction of the laser and a preset conductive area 42 defined by each grating groove 41, and a light-transmitting insulating layer 101 at least covering the sidewalls of the grating groove 41 is formed in the grating groove 41; the top surface electrode layer 50 is in contact with and connected to the top surface of the preset conductive area 42; wherein the carriers injected through the top surface electrode layer 50 flow through the preset conductive area 42 and the bottom of the grating groove 41 in sequence and then diffuse laterally to the multi-quantum well active layer 20 to form a carrier distribution area for providing pumping.

[0089] As an example, see Fig.13A grating structure 40 including a plurality of grating grooves 41 distributed at periodic intervals (e.g., uniform intervals) along the waveguide direction of the laser and a preset conductive region 42 defined by each grating groove 41 can be formed in the ridge-shaped doped dielectric layer 30. The distance between the bottom of the grating groove 41 and the multi-quantum well active layer 20 is small, and the diffusion of the injected current is limited, so that in the direction of the laser cavity, the carrier density fluctuates periodically with the grating groove 41, and a certain degree of gain modulation is generated. Since the phase of the gain coupling and the phase of the refractive index coupling in the present application are consistent and will not cancel each other, the gain modulation intensity and the refractive index modulation intensity can be adjusted by setting the shape, size and number of the grating grooves 41, so as to effectively improve the performance of the laser, reduce its manufacturing cost, and improve its yield and reliability.

[0090] As an example, see Fig.13 , the shape, size and number of the grating grooves 41 can be set so that under different injection currents, the carriers injected through the top electrode layer 50 flow through the preset conductive area 42 and the bottom of the grating grooves 41 in sequence and then diffuse laterally to the multi-quantum well active layer 20, forming a carrier distribution area with uniform carrier distribution, providing uniform carriers for pumping for the laser, and effectively improving the performance and stability of the laser. For example, the shape of the longitudinal section of the grating grooves 41 along the waveguide direction perpendicular to the laser can be set to include at least one of a rectangle, a groove shape and an inverted trapezoid.

[0091] As an example, see Fig.13 Since the grating structure 40 includes a plurality of grating grooves 41 periodically distributed along the waveguide direction of the laser and a preset conductive region 42 defined by each grating groove 41, that is, the distribution of the grating grooves 41 is periodic, the grating duty cycle of the grating structure 40 is associated with the gain modulation intensity of the ridge laser structure, wherein the grating period is the average spacing between adjacent grooves, and the grating duty cycle is the ratio of the area of ​​the positive projection of the preset conductive region 42 on the upper surface of the first doped medium layer 10 between adjacent grating grooves to the grating period; the grating order of the grating structure 40 is associated with the refractive index modulation intensity of the ridge laser structure.

[0092] A grating structure including a plurality of grating grooves periodically distributed along the waveguide direction of the laser and a preset conductive area defined by each grating groove is formed on the ridge-shaped doped medium layer. The grating groove is an electrical insulator, which limits the flow area of ​​the injected current. When the distance between the bottom of the grating groove and the multi-quantum well active layer is small, the diffusion of the injected current at the bottom of the grating groove is limited, which will cause the carrier density to fluctuate periodically along the grating groove in the direction of the laser cavity, resulting in a certain degree of gain modulation. Since the phase of the gain coupling in the present application is consistent with the phase of the refractive index coupling and will not offset each other, the gain modulation intensity and the refractive index modulation intensity can be adjusted by setting the shape, size and number of the grating grooves, which effectively improves the performance of the laser. The reflective surface can be used to realize the asymmetric mirror feedback of the laser to break the degenerate mode and realize the stable single-mode output of the laser. Since the reflective surface in the present application is formed in the process of preparing the grating structure, the process steps introduced by adding the reflective surface are effectively reduced, the manufacturing cost of the laser structure is reduced, and the yield and reliability of the prepared laser structure are improved.

[0093] As an example, see Figure 13-14 , establish a corresponding relationship between the grating duty cycle of the grating structure 40 and the gain modulation intensity of the ridge laser structure, and the gain modulation intensity of the ridge laser structure can be adjusted by setting the grating duty cycle of the grating structure 40. Establish a corresponding relationship between the grating order of the grating structure 40 and the refractive index modulation intensity of the ridge laser structure, and the refractive index modulation intensity of the ridge laser structure can be adjusted by setting the grating order of the grating structure 40. Thereby increasing the degree of freedom in preparing the gain modulation intensity and / or refractive index modulation intensity of the laser.

[0094] As an example, see Figure 13-Figure 16 , when the grating groove is formed in the ridge-shaped doped dielectric layer, the depth of the grating groove can be set to 0.6hh; where h is the thickness of the ridge-shaped doped dielectric layer. For example, the depth of the grating groove can be set to 0.6h, 0.8h, 0.9h or h. In this embodiment, the bottom of the grating groove is close to the multi-quantum well active layer, so that the pattern formed by the carriers formed by the current injected through the top electrode layer is well maintained below the grating groove, modulating the distribution of the carriers and further modulating the gain of the ridge laser structure. Comparison Fig.15 and Fig.16 It can be found that the higher the amplitude of the injected current, the greater the modulation degree of the carrier distribution.

[0095] Please note that the above-described embodiments are for illustrative purposes only and do not imply limitation of the present application. It should be understood that, unless clearly stated herein, the execution of the steps described does not have strict order restrictions, and these steps can be performed in other orders. Moreover, at least a portion of the steps described may include a plurality of sub-steps or a plurality of stages, and these sub-steps or stages are not necessarily performed at the same time, but can be performed at different times, and the execution order of these sub-steps or stages is not necessarily performed in sequence, but can be performed in turn or alternately with at least a portion of other steps or sub-steps or stages of other steps.

[0096] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0097] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. As long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0098] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. The protection scope of the patent application shall be subject to the attached claims.

Claims

1. A method for preparing a laser structure, characterized in that: include: Providing an epitaxial structure, the epitaxial structure comprising a substrate, a first doped medium layer, a multi-quantum well active layer and a ridge-shaped doped medium layer stacked in sequence; A grating structure is formed on the ridge-shaped doped medium layer and a reflecting surface is formed at one end of the grating structure, wherein the grating structure comprises a plurality of grating grooves periodically distributed along the waveguide direction of the laser and a preset conductive region defined by each of the grating grooves, and a light-transmitting insulating layer at least covering the sidewalls of the grating grooves is formed in the grating grooves; the light reflected back to the laser cavity by the reflecting surface has a controllable preset phase; The reflection surface and the grating structure are defined by an opening pattern on the same first mask layer; the opening pattern at least defines the preset phase; the grating groove is formed in the ridge-shaped doped medium layer; The reflective surface penetrates the ridge-shaped doped medium layer and the multi-quantum well active layer in a direction perpendicular to the substrate and extends into the first doped medium layer, and the reflective surface is located on the same side of the grating groove; A top surface electrode layer is formed, and the top surface electrode layer forms an ohmic electrical contact with at least the top surface of the preset conductive region, so that the carriers injected through the top surface electrode layer flow through the preset conductive region and the ridge-shaped doped medium layer under the grating groove in sequence and then diffuse laterally to the multi-quantum well active layer, forming a carrier distribution region for providing pumping.

2. The method for preparing a laser structure according to claim 1, characterized in that: The opening pattern includes a first opening pattern and a second opening pattern; The step of forming a grating structure on the ridge-shaped doped medium layer and forming a reflective surface on the end surface of the grating structure comprises: Forming a first mask layer on the upper surface of the ridge-shaped doped dielectric layer, the first mask layer comprising the first opening pattern and the second opening pattern formed by photolithography and removing a portion of the first mask layer, the first opening pattern being used to define the position and shape of the grating groove, and the second opening pattern being used to define the position and shape of the reflection surface with a preset phase; forming a second mask layer, wherein the second mask layer at least covers the second opening pattern and exposes the first opening pattern; Etching and removing a portion of the first mask layer and a portion of the ridge-shaped doped dielectric layer based on the first opening pattern to form the grating groove; forming a light-transmitting insulating material layer, wherein the light-transmitting insulating material layer fills the grating grooves and covers the upper surface of the second mask layer; removing part of the light-transmitting insulating material layer, part of the second mask layer, part of the ridge-shaped doped dielectric layer, part of the multi-quantum well active layer and part of the first doped dielectric layer to form the reflective surface; The light-transmitting insulating material layer located on the upper surface of the grating groove is removed to form the grating structure, and the remaining light-transmitting insulating material layer constitutes a light-transmitting insulating layer.

3. The method for preparing a laser structure according to claim 2, characterized in that: After forming the light-transmitting insulating material layer, the method further includes: Removing the light-transmitting insulating material layer located on the upper surface of the grating groove to form the grating structure, and the remaining light-transmitting insulating material layer constitutes a light-transmitting insulating layer; forming a top surface electrode layer, wherein the top surface electrode layer at least covers the upper surface of the preset conductive region and forms an ohmic electrical contact with the top surface of the preset conductive region; forming a third mask layer, wherein the third mask layer at least covers the upper surface of the top electrode layer; Part of the light-transmitting insulating material layer, part of the second mask layer, part of the ridge-shaped doped dielectric layer, part of the multi-quantum well active layer and part of the first doped dielectric layer are removed to form the reflective surface.

4. The method for preparing a laser structure according to claim 2 or 3, characterized in that: The second mask layer and the first mask layer have different etching rates.

5. The method for preparing a laser structure according to claim 1, characterized in that: The step of forming a grating structure on the ridge-shaped doped dielectric layer and forming a reflective surface at one end of the grating structure comprises: forming a first mask layer on the upper surface of the ridge-shaped doped dielectric layer, the first mask layer comprising a first opening pattern and a second opening pattern formed by photolithography and removing a portion of the first mask layer, the first opening pattern being used to define the position and shape of the grating groove, and the second opening pattern being used to define the position and shape of the reflective surface with a preset phase; forming a fourth mask layer, wherein the fourth mask layer at least covers the first opening pattern and exposes the second opening pattern; removing part of the ridge-shaped doped medium layer, part of the multi-quantum well active layer and part of the first doped medium layer to form the reflective surface; removing the fourth mask layer to expose the first opening pattern, and etching and removing a portion of the first mask layer and a portion of the ridge-shaped doped dielectric layer based on the first opening pattern to form the grating groove; A light-transmitting insulating layer is formed at least in the grating groove to form the grating structure.

6. The method for preparing a laser structure according to claim 5, characterized in that: The fourth mask layer has a different etching rate from the first mask layer.

7. The method for preparing a laser structure according to claim 2 or 3 or 5 or 6, characterized in that: Before forming the grating structure and the reflecting surface, or between forming the grating structure and the reflecting surface, or after forming the grating structure and the reflecting surface, the method further comprises: performing at least one laser waveguide definition process on the obtained structure.

8. The method for preparing a laser structure according to claim 2, 3, 5 or 6, characterized in that: After forming the reflecting surface, the method further includes: A reflective film is formed on the reflective surface; the material of the reflective film includes a high-reflective material and / or an anti-reflective material.

9. The method for preparing a laser structure according to any one of claims 1 to 3 or 5 or 6, characterized in that: The light-transmitting insulating layer includes a dielectric material and / or a polymer material.

10. A laser structure, characterized in that: include: The laser structure is prepared by the laser structure preparation method according to any one of claims 1 to 9.

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