A distributed feedback laser and its preparation method, and laser chip

Abstract

The present application relates to the field of laser preparation technology and provides a distributed feedback laser and its preparation method, as well as a laser chip. The preparation method of the distributed feedback laser includes: providing a substrate; sequentially growing an n-type doped layer, a p-type separate confinement layer and a p-type confinement layer on the substrate; + / n + Tunnel junction; etching p + / n + Tunnel junction, forming multiple gratings; growing n-type cladding layer, undoped active layer and p-type cladding layer on the grating in sequence; growing first electrode and second electrode on substrate and p-type cladding layer respectively; performing annealing. + / n + The tunnel junction method can form multiple spaced gratings in a low-temperature environment, and use an n-type cladding layer to cover the grating to form a micro-current injection area. The grating can realize the arrangement of patterns in a variety of light-emitting modes and realize light emission in all directions to meet the different light-emitting characteristics requirements of distributed feedback lasers.

Description

Technical Field

[0001] The present application relates to the field of laser preparation technology, and in particular to a distributed feedback laser and a preparation method thereof, and a laser chip. Background Art

[0002] Distributed Feedback Laser (DFB) is a semiconductor laser that uses a Bragg grating to provide feedback mechanism. It is widely used in optical communications, gas sensing, medical equipment, laser printing and other fields.

[0003] Currently, the fabrication process for DFB lasers requires the precise implantation of Bragg gratings during the epitaxial growth phase of semiconductor materials, a step that demands extremely high process precision. Due to the high temperatures of epitaxial growth, the grating grooves may melt back, causing the grating to deform or even disappear, thus affecting laser performance.

[0004] Therefore, there is an urgent need for a preparation method for a DFB laser that can reduce the grating epitaxial growth temperature and ensure the performance. Summary of the Invention

[0005] The present application provides a distributed feedback laser and its preparation method, as well as a laser chip, to solve the technical problem that the epitaxial growth temperature is high and affects the performance of the laser.

[0006] The first aspect of the present application provides a method for preparing a distributed feedback laser, comprising: providing a substrate; sequentially growing an n-type doped layer, a p-type separate confinement layer and a p-type confinement layer on the substrate; + / n + Tunnel junction; etching p + / n + Tunnel junctions are formed to form multiple gratings; an n-type cladding layer, an undoped active layer and a p-type cladding layer are sequentially grown on the gratings; a first electrode and a second electrode are grown on the substrate and the p-type cladding layer respectively; and an annealing process is performed.

[0007] In some possible implementations, etching p + / n + Tunnel junction, forming multiple gratings, including: + / n + +Prepare a first mask layer on the tunnel junction; the first mask layer includes a plurality of strip structures arranged in sequence; etch the p + / n + Tunnel junction; removing the first mask layer to obtain multiple gratings.

[0008] In some possible implementations, etching p + / n + Tunnel junction, forming multiple gratings, including:+ / n + A second mask layer is prepared on the tunnel junction; the second mask layer includes a patterned mask layer; the second mask layer and the p-type layer covered by the second mask layer are etched + / n + Tunnel junction, multiple gratings are obtained.

[0009] In some feasible implementations, multiple gratings are arranged in an array.

[0010] In some possible implementations, p + / n + The thickness of the tunnel junction is greater than or equal to 10 nm.

[0011] In some feasible implementations, the width of the grating is 50-500 nm; and the distance between the centers of any two adjacent gratings is 0.8 μm-1.2 μm.

[0012] In some feasible implementations, before performing the annealing process, the method for preparing a distributed feedback laser further includes: performing a patterning process on the first electrode and / or the second electrode.

[0013] The first aspect of the present application provides a method for preparing a distributed feedback laser, which provides a method for preparing a grating with a different coupling mechanism from the groove method, and uses etching p + / n + A semiconductor heterostructure laser is obtained by forming multiple spaced gratings using a tunnel junction method. These gratings are then covered with an n-type cladding layer to create a microcurrent injection region. The multiple gratings in this fabrication method can be arranged in various patterns to achieve the desired light emission pattern. This allows for light emission in various directions, meeting the diverse light emission characteristics of distributed feedback lasers.

[0014] The distributed feedback laser provided in the second aspect of the present application is prepared by the preparation method of the distributed feedback laser provided in the first aspect, and the distributed feedback laser comprises a substrate; an n-type doped layer and a p-type separate confinement layer sequentially arranged on the substrate; a plurality of gratings arranged in the p-type separate confinement layer; wherein the gratings are formed by the p-type separate confinement layer. + / n + The tunnel junction is obtained by etching; an n-type cladding layer, an undoped active layer and a p-type cladding layer are sequentially arranged on the grating; a first electrode is arranged on the side of the substrate away from the n-type cladding layer; and a second electrode is arranged on the p-type cladding layer.

[0015] In some possible implementations, the grating includes a stripe grating.

[0016] A third aspect of the present application provides a laser chip, comprising a circuit and the distributed feedback laser provided by the second aspect applied to the circuit.

[0017] The distributed feedback lasers in the second and third aspects of this application are prepared by the preparation method of the distributed feedback laser provided by the first aspect. Therefore, the beneficial technical effects thereof can be referred to the first aspect and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0019] Figure 1 This is a flow chart of a method for preparing a distributed feedback laser provided in an embodiment of the present application;

[0020] Figure 2 This is one of the process flow charts for preparing a distributed feedback laser provided in an embodiment of the present application;

[0021] Figure 3 This is a process flow chart for preparing a grating provided in an embodiment of the present application;

[0022] Figure 4 This is a flow chart of another grating preparation process provided in an embodiment of the present application;

[0023] Figure 5 This is a schematic diagram of an arrangement of multiple gratings provided in an embodiment of the present application;

[0024] Figure 6 This is the second process flow chart of a distributed feedback laser preparation process provided in an embodiment of the present application;

[0025] Figure 7 This is a partial schematic diagram of the light output path of a distributed feedback laser provided in an embodiment of the present application.

[0026] Graphic mark:

[0027] 100, distributed feedback laser; 10, substrate; 20, n-type doping layer; 30, p-type separate confinement layer; 40, p + / n + Tunnel junction; 41, grating; 411, first grating; 412, second grating; 413, third grating; a1, first mask layer; a2, second mask layer; 50, n-type cladding layer; 60, undoped active layer; 70, p-type cladding layer; 80, first electrode; 90, second electrode. DETAILED DESCRIPTION

[0028] The following will clearly describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, other embodiments obtained by ordinary technicians in this field without making any creative work are all within the scope of protection of this application.

[0029] Hereinafter, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified with "first," "second," etc., may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0030] In addition, in this application, directional terms such as "upper", "lower", "inner" and "outer" are defined relative to the orientation of the components in the drawings. It should be understood that these directional terms are relative concepts. They are used for relative description and clarification, and they can change accordingly according to changes in the orientation of the components in the drawings.

[0031] To facilitate the technical solution of the application, some concepts involved in this application are first explained below.

[0032] The manufacturing process for DFB lasers is highly complex, encompassing multiple steps including epitaxial growth, photolithography, etching, coating, and cutting. During the fabrication process, a Bragg grating is implanted during the epitaxial growth phase of the semiconductor material, which requires high epitaxial growth temperatures. While these temperatures vary depending on the fabrication method, they typically exceed 1000°C, sometimes even exceeding 1500°C. At these high temperatures, the grating grooves may melt back, causing the grating to deform or even disappear, thereby impacting laser performance.

[0033] In order to solve the above technical problems, an embodiment of the present application provides a method for preparing a distributed feedback laser, which can effectively reduce the preparation temperature of the grating, thereby ensuring the performance of the laser.

[0034] Figure 1 This is a flow chart of a method for preparing a distributed feedback laser provided in an embodiment of the present application; Figure 2 This is one of the process flow charts for preparing a distributed feedback laser provided in an embodiment of the present application.

[0035] Combine Figure 1 and Figure 2 As shown, the method for preparing the distributed feedback laser provided in the embodiment of the present application can be implemented by the following steps S1 to S6.

[0036] Step S1: providing a substrate 10.

[0037] In step S1, substrate 10 may include one of a GaAs substrate, an InP substrate, a SiC substrate, a GaSb substrate, or an Al2O3 substrate. The structure of substrate 10 can be adaptively selected based on the application scenario of the distributed feedback laser. For example, in a mid-infrared communication scenario, an InP substrate may be preferred; or in a near-infrared scenario, a GaAs substrate may be preferred.

[0038] The substrate 10 must meet cleanliness and flatness requirements to provide a good foundation for subsequent epitaxial growth.

[0039] In some feasible implementations, after step S1 , the method for preparing a distributed feedback laser may further include step S11 .

[0040] Step S11: cleaning and surface flatness treatment are performed on the substrate 10 .

[0041] The cleaning process may include using plasma water, alcohol or hydrogen peroxide to clean the surface of the substrate 10. The flatness process may include grinding or polishing the surface of the substrate 10 to facilitate the growth of subsequent structural layers.

[0042] Step S2: sequentially growing an n-type doped layer 20, a p-type separate confinement layer 30 and a p-type confinement layer on the substrate 10. + / n + Tunnel junction 40.

[0043] Herein, step S2 can be implemented by the following steps S21 to S23.

[0044] Step S21 : depositing an n-type doping layer 20 on the substrate 10 .

[0045] The n-type doped layer 20 may include one of n-type aluminum gallium arsenide (AlGaAs), n-type gallium arsenide (GaAs), or n-type gallium nitride (GaN). Of course, the n-type doped layer 20 may also have other structures.

[0046] Step S22 : depositing a p-type separate confinement layer 30 on the n-type doped layer 20 .

[0047] The p-type separate confinement layer 30 (Separate Confinement Heterostructure, SCH) can include one of p-type aluminum gallium arsenide (AlGaAs), p-type gallium nitride (GaN), p-type aluminum gallium nitride (AlGaN), or p-type InGaAsP (Indium Gallium Arsenide Phosphate). Of course, the p-type separate confinement layer 30 can also include other structures.

[0048] Step S23: Depositing p-type separate confinement layer 30 + / n + Tunnel junction 40.

[0049] Among them, p + / n + Tunnel junction 40 may include p + GaAs / n + Type InGaAsP, p + InGaAsP / n + InP or p + AlGaN / n + One of the GaN types.

[0050] In some feasible implementations, the growth method in step S2 may include metal-organic chemical vapor deposition (MOCVD). That is, in steps S21 to S23, the parameters of the deposition technology of different structural layers can be the same or different, and the parameters of the deposition technology can be adaptively adjusted according to the specific structure of the structural layer. Among them, different structural layers can be combined at will, such as the n-type doped layer 20 is n-type gallium arsenide (GaAs), the p-type separate confinement layer 30 is p-type gallium nitride (GaN), and the p ... doped layer 20 is p-type gallium nitride (GaN), and the p-type doped layer 20 is p-type gallium nitride (GaN). + / n + Tunnel junction 40 may include p + GaAs / n + Type InGaAsP; or, if the n-type doped layer 20 is n-type aluminum gallium nitride (AlGaN), the p-type separate confinement layer 30 is p-type aluminum gallium nitride (AlGaN), p + / n + Tunnel junction 40 may include p + GaAs / n + TypeInGaAsP.

[0051] That is to say, the specific structures of the n-type doped layer 20 and the p-type individual confinement layer 30 can be the same or different, and the n-type doped layer 20 and the p-type individual confinement layer 30 are different from each other. + / n + The specific structure of the tunnel junction 40 can be flexibly adjusted.

[0052] It should be emphasized that the growth thickness and quality of each structural layer can be controlled by controlling parameters such as deposition temperature and gas flow rate.

[0053] After step S2 is completed, you can get Figure 2 The structure shown in (a).

[0054] Step S3: Etching p+ / n + The tunnel junction 40 forms a plurality of gratings 41 , wherein the plurality of gratings 41 are sequentially spaced and arranged along a direction.

[0055] In step S3, the etching depth is p + / n + The thickness of the tunnel junction 40 is such that the top surface of the p-type individual confinement layer 30 is exposed between adjacent gratings 41. The plurality of gratings 41 formed by etching can be as follows: Figure 2 As shown in (b) of FIG. For example, the multiple gratings 41 may be arranged in parallel, or the multiple gratings 41 may be arranged non-parallel. When the multiple gratings 41 are arranged in parallel, the multiple gratings 41 may be arranged at equal intervals or at non-equal intervals.

[0056] It should be emphasized that MOCVD is used in this application to deposit p + / n + The tunnel junction 40 is used to form the subsequent grating 41, and the deposition temperature can be in the range of 700°C to 800°C. In this way, the preparation temperature of the grating 41 can be greatly reduced, the preparation process is simple, the production cost is reduced, and the technical problem that the grating 41 is easily damaged during the epitaxial stage is effectively solved. The performance of the distributed feedback laser is effectively guaranteed, so that the distributed feedback laser can achieve the requirements of high power, low noise and high stability. Moreover, the preparation method of the distributed feedback laser provided in the embodiment of the present application adopts a non-groove form in the preparation of the grating 41. In this way, it can ensure that there is a good growth relationship between the grating 41 and the p-type separate confinement layer 30, and no pores or gaps will be left during the growth process, thereby ensuring the performance of the distributed feedback laser prepared subsequently.

[0057] Figure 3 This is a process flow chart for preparing a grating provided in an embodiment of the present application.

[0058] In some possible implementations, combined with Figure 3 As shown, step S3 can be implemented by the following steps S31a to S33a.

[0059] Step S31a: In p + / n + A first mask layer a1 is formed on the tunnel junction 40 .

[0060] The first mask layer a1 includes a plurality of strip structures arranged at intervals.

[0061] After step S31a is completed, the following can be obtained: Figure 3 In this implementation, multiple strip structures are arranged at equal intervals, and multiple strip structures can be arranged in parallel.

[0062] Step S32a: etching the p-type film not covered by the first mask layer a1. + / n + Tunnel junction 40.

[0063] In step S32a, a photolithography process may be used to etch p + / n + Tunnel junction 40, etching depth is p + / n + The thickness of the tunnel junction 40 is determined by etching, and the top surface of the p-type individual confinement layer 30 is exposed at the etching site. After step S32a is completed, the following can be obtained: Figure 3 The structure shown in (b).

[0064] Step S33a: removing the first mask layer a1 to obtain a plurality of gratings 41.

[0065] In step S33a, a removal agent may be used to remove the first mask layer a1. The selection of the removal agent may be adaptively adjusted according to the specific type of the first mask layer a1.

[0066] After the first mask layer a1 is removed, multiple gratings 41 can be obtained, such as Figure 3 The structure shown in (c).

[0067] Figure 4 This is a process flow chart of another grating preparation process provided in an embodiment of the present application.

[0068] In some possible implementations, combined with Figure 2 and Figure 4 As shown, step S3 can also be implemented by the following steps S31b to S32b.

[0069] Step S31b: In p + / n + A second mask layer a2 is formed on the tunnel junction 40 .

[0070] The second mask layer a2 includes a patterned mask layer. In this implementation, the patterned mask layer may be a mask layer after removing a plurality of strip structures. Figure 4 As shown in (a).

[0071] Step S32b: etching the second mask layer a2 and the p covered by the second mask layer a2 + / n + The tunnel junction 40 is formed to obtain a plurality of gratings 41. The gratings 41 are as follows: Figure 4 As shown in (b).

[0072] In step S32b, the patterned mask layer and the p-type layer covered by the patterned mask layer may be etched by photolithography. + / n+ Tunnel junction 40, etching depth is p + / n + The thickness of the tunnel junction 40. + / n + The tunnel junction 40 is etched to form a plurality of stripe structures to obtain a plurality of gratings 41 .

[0073] It should be emphasized that the above Figure 3 and Figure 4 The size, position, and number of the fabricated gratings 41 shown are identical, and are merely exemplary of how different methods can be used to fabricate the gratings 41. In other feasible implementations, the size, position, and number of the gratings 41 can be adaptively adjusted. For example, the sizes of the multiple gratings 41 can be the same or different, and the spacing between the multiple gratings 41 can be the same or different.

[0074] In some possible implementations, see Figure 2 In (b), the width d of the grating 41 can be in the range of 50 nm to 500 nm. The distance L between the centers of two adjacent gratings 41 can be in the range of 0.8 μm to 1.2 μm. Properly setting the width of the grating 41 and the distance between two adjacent gratings 41 can adjust the phase of the distributed feedback laser and ensure the output power of the distributed feedback laser.

[0075] For example, the width d of the grating 41 may be one of 50 nm, 150 nm, 250 nm, 350 nm, or 450 nm. Of course, the width d of the grating 41 may also be other sizes within a range from 50 nm to 500 nm.

[0076] For example, the distance L between the centers of two adjacent gratings 41 can be one of 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm or 1.2 μm. Of course, the distance L between the centers of two adjacent gratings 41 can also be other sizes within the range of 0.8 μm to 1.2 μm.

[0077] Figure 5 This is a schematic diagram of the arrangement of multiple gratings provided in an embodiment of the present application. Figure 5 Middle (a) to Figure 5 (g) shows different arrangements of the plurality of gratings 41 .

[0078] See also Figure 5As shown in (a), the p-type individual confinement layer 30 is circular in shape. The substrate 10 and n-type doped layer 20 are not shown in the figure. The p-type individual confinement layer 30 has the same shape as the substrate 10. In this implementation, multiple gratings 41 are arranged in an array. Specifically, there are three gratings 41, all of which have the same length, less than or equal to the diameter of the p-type individual confinement layer 30.

[0079] See also Figure 5 As shown in (b), the p-type individual confinement layer 30 is circular. There are three gratings 41, each of different sizes. The gratings 41 may include a first grating 411, a second grating 412, and a third grating 413. The lengths of the first grating 411 and the third grating 413 may be the same and greater than the length of the second grating 412.

[0080] See also Figure 5 As shown in (c), the p-type individual confinement layer 30 is circular. There are three gratings 41, each of different sizes. The gratings 41 may include a first grating 411, a second grating 412, and a third grating 413. The lengths of the first grating 411 and the third grating 413 may be the same and smaller than the length of the second grating 412; and the widths of the first grating 411 and the third grating 413 may be the same and smaller than the width of the second grating 412.

[0081] See also Figure 5 As shown in (d), the p-type individual confinement layer 30 is circular. There are three gratings 41, each of different sizes. The gratings 41 may include a first grating 411, a second grating 412, and a third grating 413. The lengths of the first grating 411 and the third grating 413 may be the same and smaller than the length of the second grating 412. The angle between the central axis z1 of the first grating 411 and the central axis z2 of the second grating 412 may be α1, and the angle between the central axis z2 of the second grating 412 and the central axis z3 of the third grating 413 may be α2. The angles α1 and α2 may be the same or different. When the angles α1 and α2 are the same, the first grating 411 and the third grating 413 are arranged parallel to each other.

[0082] See also Figure 5 As shown in (e), the shape of the p-type individual confinement layer 30 is circular, the number of gratings 41 is three, and the gratings 41 may include a first grating 411, a second grating 412, and a third grating 413. Figure 5The difference in (d) is that the first grating 411 is attached to one end of the second grating 412, and the third grating 413 is attached to the other end of the second grating 412, forming an "N" or "Z" shaped grating 41 structure. Of course, other patterns, such as an "M" shape, can be formed by adjusting the number and position of the gratings 41.

[0083] See also Figure 5 As shown in (f), the p-type individual confinement layer 30 is square in shape. There are four gratings 41, which are spaced apart along a first direction A of the p-type individual confinement layer 30. Each grating 41 extends along a second direction B of the p-type individual confinement layer 30. The first direction A may be the length of the p-type individual confinement layer 30. In this case, the length of the grating 41 may be the same as the width of the p-type individual confinement layer 30, or may be less than the width of the p-type cladding layer 70.

[0084] See also Figure 5 As shown in (g), the p-type individual confinement layer 30 is square in shape and includes three gratings 41 of different sizes. The gratings 41 may include a first grating 411, a second grating 412, and a third grating 413. The lengths of the first grating 411 and the third grating 413 may be the same and greater than the length of the second grating 412. The three gratings 41 are spaced apart along the second direction B of the p-type individual confinement layer 30, and each grating 41 extends along the first direction A of the p-type individual confinement layer 30. The first direction A may be the length direction of the p-type individual confinement layer 30, and the second direction B may be the width direction of the p-type individual confinement layer 30. Alternatively, the p-type individual confinement layer 30 may be square in shape and have the same dimensions in the first and second directions A and B.

[0085] It should be emphasized that Figure 5 As shown in (a) to (c), (f) and (g), the plurality of gratings 41 are arranged in parallel. Figure 5 As shown in (d) and (e), the plurality of gratings 41 are arranged in a non-parallel relationship. Figure 5 The p-type individual confinement layer 30 shown in (a) to (e) is circular. Figure 5 The p-type individual confinement layer 30 shown in (f) and (g) is square. Figure 5 As shown in (a) to (e) and (g), the number of gratings 41 is three. Figure 5As shown in (f), there are four gratings 41, and the above is for illustrative purposes only. The specific number, size, position, and arrangement of the gratings 41 can be adaptively adjusted using the first mask layer a1 or the second mask layer a2. The length of the gratings 41 can be adaptively adjusted based on the shape of the p-type individual confinement layer 30. For example, when the p-type individual confinement layer 30 is circular, the length of the gratings 41 is less than or equal to the diameter of the p-type individual confinement layer 30; or when the p-type individual confinement layer 30 is square, the length of the gratings 41 is less than or equal to the length of the diagonal of the p-type individual confinement layer 30. The spacing distribution of the gratings 41 in this application can refer to spacing distribution at both ends of the gratings 41 or spacing distribution at one end of the gratings 41.

[0086] In this way, the prepared grating 41 can be flexibly adjusted according to the use requirements of distributed feedback, and can form a special gain and refractive index modulation distribution to couple light waves in various directions, optimize the light wave coupling mechanism, and enable light waves in various directions propagating in the heterogeneous structure to interact between gratings 41 with different distributions, thereby realizing that the laser emitted by the distributed feedback laser can produce multiple characteristics.

[0087] Specifically, etching p + / n + The method of forming the grating 41 in the form of the tunnel junction 40 can minimize the height of the grating 41 .

[0088] In some possible implementations, p + / n + The thickness of the tunnel junction 40 is greater than or equal to 10 nm, that is, p + / n + The minimum thickness of the tunnel junction 40 can be 10 nm, so the minimum height of the prepared grating 41 can be 10 nm. Under the premise of ensuring the light extraction effect, the size of the grating 41 can be reduced.

[0089] In some possible implementations, p + / n + The doping level of the tunnel junction 40 is heavily doped to 10 19 cm -3 above, enabling electrons to tunnel through the thin boundary layer of the junction.

[0090] It is worth noting that precise control of p + / n + The thickness of the tunnel junction 40 and the specific values ​​of the doping level are determined to form a desired composite refraction and gain distribution, thereby matching the use requirements of the distributed feedback laser.

[0091] Figure 6This is the second process flow chart of a distributed feedback laser preparation process provided in an embodiment of the present application.

[0092] Combine Figure 1 、 Figure 2 and Figure 6 As shown, step S4: sequentially growing an n-type cladding layer 50 , an undoped active layer 60 and a p-type cladding layer 70 on the grating 41 .

[0093] In some feasible implementations, step S4 can be implemented by the following steps S41 to S43.

[0094] Step S41 : growing an n-type cladding layer 50 on the grating 41 .

[0095] In step S41, an n-type cladding layer 50 is grown synchronously on the surface of the grating 41 and the surface of the p-type individual confinement layer 30, so that the n-type cladding layer 50 can evenly cover the p-type individual confinement layer 30 and the grating 41, and no air holes or gaps are generated between the grating 41 and the n-type cladding layer 50, thereby effectively improving the structural performance of the n-type cladding layer 50 and thus effectively ensuring the performance of the distributed feedback laser. After the preparation in step S42 is completed, the obtained Figure 2 The structure shown in (c) is shown in FIG. Here, the thickness of the n-type cladding layer 50 is greater than the height of the grating 41 .

[0096] In some feasible implementations, the n-type cladding layer 50 may include one of n-type gallium arsenide (GaAs), n-type gallium nitride (GaN), or n-type aluminum gallium nitride (AlGaN). Of course, the n-type cladding layer 50 may also include other structural layers with cladding functions.

[0097] Step S42 : growing an undoped active layer 60 on the n-type cladding layer 50 .

[0098] The undoped active layer 60 provides a location for subsequent electron-hole recombination and luminescence. The quality and performance of the undoped active layer 60 are directly related to the luminous efficiency and output power of the distributed feedback laser. Therefore, strict control of various parameters during the growth process, such as temperature, pressure, and gas composition, is required to ensure that the undoped active layer has a complete crystal structure, few defects, and a uniform thickness that meets the requirements of distributed feedback lasers.

[0099] The undoped active layer 60 may include one of indium gallium arsenide phosphide (InGaAsP), aluminum indium gallium arsenide (InGaAlAs), aluminum gallium arsenide (AlGaAs) or aluminum gallium indium phosphide (AlGaInP). Of course, the undoped active layer 60 may also include other structural layers.

[0100] After the preparation in step S42 is completed, Figure 6 The structure shown in (a).

[0101] Step S43 : growing a p-type cladding layer 70 on the undoped active layer 60 .

[0102] During the preparation process, the quality and thickness of the p-type cladding layer 70 are guaranteed by controlling growth parameters (such as temperature and time). It should be emphasized that the materials of the n-type cladding layer 50 and the p-type cladding layer 70 can be set correspondingly or not.

[0103] After the preparation in step S43 is completed, Figure 6 The structure shown in (b).

[0104] Step S5 : growing a first electrode 80 and a second electrode 90 on the substrate 10 and the p-type cladding layer 70 respectively.

[0105] In some feasible implementations, step S5 can be implemented by the following steps S51 and S52.

[0106] Step S51 : growing a first electrode 80 on a side of the substrate 10 facing away from the n-type cladding layer 50 .

[0107] Step S52 : growing the second electrode 90 on the p-type cladding layer 70 .

[0108] In step S51 and step S52, the specific materials of the first electrode 80 and the second electrode 90 can be set accordingly, and the preparation processes of the first electrode 80 and the second electrode 90 can be the same or different. Among them, the first electrode 80 can be an n-type electrode, and the second electrode 90 can be a p-type electrode.

[0109] After step S5 is completed, Figure 6 The distributed feedback laser 100 is shown in (c).

[0110] In some feasible implementations, the n-type electrode and the p-type electrode may be deposited by evaporation or sputtering. The n-type electrode may be Al, and the p-type electrode may be Ag or Al.

[0111] It should be emphasized that the specific materials of the first electrode 80 and the second electrode 90 provided in the embodiment of the present application can be the same or different, and the embodiment of the present application does not make any specific limitation.

[0112] In some feasible implementations, after the first electrode 80 and the second electrode 90 are prepared, the method for preparing a distributed feedback laser may further include:

[0113] Step S53: performing patterning on the first electrode 80 and / or the second electrode 90 .

[0114] In step S53, a photolithography or etching process can be used to determine the shape and position of the first electrode 80 and / or the second electrode 90 to form a patterned first electrode 80 and / or a patterned second electrode 90. In this way, good ohmic contact can be ensured between the first electrode 80 and the substrate 10, and between the second electrode 90 and the p-type cladding layer 70, to achieve effective electrical injection.

[0115] When a photolithography method is used, the photolithography method can be the same as the method for preparing the stripe grating 41 in the above step S3. When an etching process is used, the etching depth can be determined by controlling etching parameters.

[0116] It is worth noting that the first electrode 80 and the second electrode 90 can be patterned simultaneously, or one of the first electrode 80 and the second electrode 90 can be patterned while the other is not. Whether the first electrode 80 and the second electrode 90 are patterned, and the specific patterns obtained by the patterning process can be adaptively adjusted according to usage requirements.

[0117] Step S6: performing annealing treatment.

[0118] Annealing treatment can repair lattice damage, optimize electrical properties, and reduce defect density.

[0119] In some feasible implementations, after the distributed feedback laser 100 is prepared, it can be further processed, including cutting, packaging, etc. The distributed feedback laser 100 is fully tested, including laser performance testing (such as wavelength, power, mode, etc.) and electrical performance testing (such as resistance, current injection, etc.) to ensure that the device meets design requirements.

[0120] Figure 7 This is a partial schematic diagram of the light output path of a distributed feedback laser provided in an embodiment of the present application.

[0121] See also Figure 7 As shown, the light emission direction of the distributed feedback laser 100 of the embodiment of the present application is emitted from the substrate 10 toward the grating 41. Among them, the light emission path of the position covered by the grating 41 is along the a11 path, and the light is emitted in a straight line. In the position not covered by the grating 41, the light emission paths converge toward the position of the grating 41 along the a21 and a31 paths respectively, and after passing through the grating 41, the light is emitted in the directions of a22 and a32 respectively.

[0122] It is worth noting that the light output path can be achieved by adjusting the width d of the grating 41. For example, when the width dimension of the grating 41 is relatively small, the light output path may include a11. When the width dimension of the grating 41 is relatively large, the light output path may include a11, a22 and a32. Similarly, the light output direction can also be achieved by adjusting the positional relationship of the grating 41. For example, when multiple gratings 41 are arranged in parallel, the light output path a22 in each grating 41 has the same direction, and the light output path a32 in each grating 41 has the same direction. For example, when multiple gratings 41 are not arranged in parallel, the light output path a22 in each grating 41 has a different direction, and the light output path a32 in each grating 41 has a different direction. In this way, the preparation method of the distributed feedback laser provided in the embodiment of the present application can adjust the light output direction by the structural size and positional relationship of the grating 41 to meet the light output requirements of different distributed feedback lasers 100.

[0123] In the method for preparing a distributed feedback laser provided in the embodiment of the present application, a method for preparing a grating 41 by a coupling mechanism different from the groove method is provided. + / n + A plurality of spaced gratings 41 are formed by tunnel junctions 40, and an n-type cladding layer 50 is used to cover the gratings 41, forming a micro-current injection region, thereby obtaining a semiconductor heterostructure laser. The multiple gratings 41 in this preparation method can be arranged in different forms to form a pattern that can achieve the desired light emission method, thereby achieving light emission in various directions to meet the different light emission characteristics required by the distributed feedback laser 100.

[0124] Corresponding to the embodiment of the method for preparing a distributed feedback laser, the present application also provides an embodiment of a distributed feedback laser 100. The distributed feedback laser 100 is prepared by the method for preparing a distributed feedback laser provided in the embodiment above.

[0125] See also Figure 6 As shown in (c), the distributed feedback laser 100 may include a substrate 10 , an n-type doped layer 20 , a p-type separate confinement layer 30 , a grating 41 , an n-type cladding layer 50 , an undoped active layer 60 , a p-type cladding layer 70 , a first electrode 80 and a second electrode 90 .

[0126] The substrate 10 can be prepared by step S1 in the above embodiment.

[0127] The n-type doping layer 20 is provided on the substrate 10 , and the n-type doping layer 20 can be prepared by step S21 provided in the above embodiment.

[0128] The p-type individual confinement layer 30 is provided on the n-type doping layer 20 . The p-type individual confinement layer 30 can be prepared by step S22 provided in the above embodiment.

[0129] The grating 41 is disposed on the p-type individual confinement layer 30. The grating 41 can be prepared by steps S23 and S3 provided in the above embodiment. The gratings 41 are sequentially spaced and arranged in a direction. The gratings 41 include strips, and there are multiple gratings 41. The multiple gratings 41 can be arranged in parallel or non-parallel. The lengths and widths of the multiple gratings 41 can be adaptively adjusted.

[0130] The n-type cladding layer 50 is provided on the grating 41 and the p-type individual confinement layer 30 . The n-type cladding layer 50 can be prepared by step S41 provided in the above embodiment.

[0131] The undoped active layer 60 is provided on the n-type cladding layer 50 . The undoped active layer 60 can be prepared by step S42 provided in the above embodiment.

[0132] The p-type cladding layer 70 is provided on the undoped active layer 60 . The p-type cladding layer 70 can be prepared by step S43 provided in the above embodiment.

[0133] The first electrode 80 and the second electrode 90 are respectively disposed on the substrate 10 and the p-type cladding layer 70 . The first electrode 80 and the second electrode 90 can be respectively prepared by step S51 and step S52 provided in the above embodiment.

[0134] The first electrode 80 and the second electrode 90 may include a patterned first electrode 80 and a patterned second electrode 90. The patterned first electrode 80 and the patterned second electrode 90 may be prepared by step S53 provided in the above embodiment.

[0135] Corresponding to the aforementioned embodiment of the distributed feedback laser 100, the present application further provides an embodiment of a laser chip, which includes a circuit and the distributed feedback laser 100 applied in the circuit.

[0136] It should be noted that those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and practicing the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of this application and include common knowledge or customary techniques in the art that are not disclosed in this application.

[0137] It will be understood that the present application is not limited to the precise construction that has been described above and shown in the accompanying drawings, and that various modifications and changes may be made without departing from the scope thereof, the true scope being indicated by the present application.

Claims

1. A method for preparing a distributed feedback laser, characterized in that: include: providing a substrate; An n-type doped layer, a p-type separate confinement layer and a p-type confinement layer are sequentially grown on the substrate. + / n + Tunnel knot; Etching the p + / n + Tunnel junction, forming a plurality of gratings; wherein the plurality of gratings are arranged in sequence along a direction; wherein the plurality of gratings are arranged in parallel with unequal lengths, or an angle is set between the central axes of two adjacent gratings; sequentially growing an n-type cladding layer, an undoped active layer, and a p-type cladding layer on the grating; growing a first electrode and a second electrode on the substrate and the p-type cladding layer respectively; Perform annealing treatment.

2. The method for preparing a distributed feedback laser according to claim 1, wherein: The etching of the p + / n + Tunnel junctions, forming multiple gratings, including: In the p + / n + A first mask layer is formed on the tunnel junction; the first mask layer includes a plurality of strip structures arranged in sequence; Etch the p not covered by the first mask layer + / n + Tunnel knot; The first mask layer is removed to obtain a plurality of the gratings.

3. The method for preparing a distributed feedback laser according to claim 1, wherein: The etching of the p + / n + Tunnel junctions, forming multiple gratings, including: In the p + / n + preparing a second mask layer on the tunnel junction; the second mask layer includes a patterned mask layer; Etching the second mask layer and the p covered by the second mask layer + / n + Tunnel junction, to obtain multiple gratings.

4. The method for preparing a distributed feedback laser according to claim 1, wherein: The width of the grating is 50nm-500nm; The distance between the centers of any two adjacent gratings is 0.8 μm-1.2 μm.

5. The method for preparing a distributed feedback laser according to claim 1, wherein: The p + / n + The thickness of the tunnel junction is greater than or equal to 10 nm.

6. The method for preparing a distributed feedback laser according to claim 1, wherein: Before the annealing process is performed, the method for preparing the distributed feedback laser further includes: Performing patterning on the first electrode and / or the second electrode.

7. A distributed feedback laser, characterized in that: Prepared by the method for preparing a distributed feedback laser according to any one of claims 1 to 6, the distributed feedback laser comprises: substrate; An n-type doping layer and a p-type separate confinement layer are sequentially provided on the substrate; A plurality of gratings are arranged in the p-type individual confinement layer; wherein the gratings are formed by p-type confinement layers arranged in the p-type individual confinement layer + / n + Tunnel junction etching is obtained; An n-type cladding layer, an undoped active layer and a p-type cladding layer are sequentially arranged on the grating; a first electrode, disposed on a side of the substrate away from the n-type doped layer; The second electrode is arranged on the p-type cladding layer.

8. The distributed feedback laser according to claim 7, characterized in that The grating includes a stripe grating.

9. A laser chip, characterized in that: include: A circuit and a distributed feedback laser according to claim 7 applied to the circuit.

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