Vertical cavity surface emitting laser

Abstract

This invention relates to the field of semiconductor laser technology, and more particularly to a vertical-cavity surface-emitting laser (VCSEL). The VCSEL comprises: a negative electrode layer, a substrate, a bottom DBR layer, a first N-type confinement layer, an active region layer, a P-type confinement layer, and a second N-type confinement layer, stacked sequentially. The second N-type confinement layer includes a heavily doped portion, a lightly doped portion, and an insulating portion. The heavily doped portion includes a main tunnel junction and a secondary tunnel junction spaced apart on the surface of the P-type confinement layer. A top DBR layer is located in the central region and includes a first portion and a second portion. A first positive electrode is located in a first edge region. A second positive electrode is located in a second edge region, and a portion is located on the top surface of the second portion. This invention facilitates a stronger PPR effect, thereby effectively improving the -3dB bandwidth of the VCSEL.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor laser technology, and particularly relates to a vertical cavity surface-emitting laser. Background Technology

[0002] Vertical-cavity surface-emitting lasers (VCSELs) possess numerous advantages, including low threshold current, circular spot size, high modulation bandwidth, single-mode lasing, ease of implementation in high-density two-dimensional arrays, and low manufacturing cost, leading to their widespread application in many fields. Particularly in optical communication, VCSELs have been successfully applied commercially, becoming a key component in high-speed data communication networks based on multimode fiber.

[0003] However, carrier-photon resonance (CPR), thermal effects, parasitic resistance, and parasitic capacitance all limit the -3dB bandwidth of vertical-cavity surface-emitting lasers (VCSELs), making it difficult to exceed 35GHz. To meet the demands of the internet, supercomputers, and data centers for single-chip speeds exceeding 200Gb / s, VCSELs face the challenge of further increasing their transmission bandwidth.

[0004] Several methods have been proposed to improve the transmission bandwidth of semiconductor lasers. Among them, external optical feedback technology has been identified as an effective technique. External optical feedback technology modulates the bandwidth by adding a sub-coupled cavity to the cavity of a vertical cavity surface-emitting laser. The design principle is to use the photon-photon resonance (PPR) effect to adjust the slow light delay time and the generated slow light feedback in the sub-coupled cavity. The light wave leaks into the sub-resonant cavity from the main resonant cavity. The light wave resonates in the sub-resonant cavity and couples with the light wave in the main resonant cavity. When the resonant frequency of the sub-resonant cavity and the frequency of the main resonant cavity meet the resonance condition, the small signal bandwidth curve will generate a resonance peak at the fundamental frequency, reducing the roll-off of the bandwidth curve. That is, the appearance of the two peaks, CPR and PPR, will make the frequency difference between the two peaks flatten. The stronger the PPR effect, the more effectively the -3dB bandwidth can be improved.

[0005] Existing vertical-cavity surface-emitting lasers (VCSELs) based on the PPR effect require light waves to leak from the main resonant cavity into the secondary resonant cavity to resonate. Furthermore, the light waves resonate back and forth within the relatively long transverse cavity, resulting in significant absorption losses. If the leakage mode efficiency of the main resonant cavity is low, it also leads to low photon-photon resonance efficiency between the entire transverse cavity and the main resonant cavity, resulting in weak coupling and poor improvement in the -3dB bandwidth. In addition, the long transverse cavity also makes the PPR mechanism difficult to control and results in poor stability. This is because most transverse cavities are passive Fabry-Perot resonators. The transverse cavity forms a transverse Fabry-Perot resonator through reflections from boundary structures (such as etched or metallic boundaries), and forms the PPR effect with specific frequencies in the main resonant cavity that meet the resonance conditions. During this process, factors such as temperature and the morphology of the resonant cavity boundaries affect the longitudinal mode distribution in the transverse direction, leading to strong randomness and instability in the PPR effect's occurrence, thus affecting its generation. Utility Model Content

[0006] In view of this, the present invention aims to provide a vertical cavity surface-emitting laser that is conducive to achieving a stronger PPR effect, thereby effectively improving the -3dB bandwidth of the vertical cavity surface-emitting laser.

[0007] To achieve the above objectives, the technical solution of this utility model is implemented as follows: This invention provides a vertical-cavity surface-emitting laser (VCSEL), comprising: a negative electrode layer, a substrate, a bottom DBR layer, a first N-type confinement layer, an active region layer, a P-type confinement layer, and a second N-type confinement layer stacked sequentially. The second N-type confinement layer includes a heavily doped portion, a lightly doped portion, and an insulating portion. The heavily doped portion includes a main tunnel junction and a secondary tunnel junction spaced apart on the surface of the P-type confinement layer. The lightly doped portion is located on the remaining surface of the P-type confinement layer, as well as on the surfaces of the main tunnel junction and the secondary tunnel junction. The top surface of the insulating portion is flush with the top surface of the lightly doped portion, and the insulating portion is located between the main tunnel junction and the secondary tunnel junction. The top surface is divided into a central region and a first edge region and a second edge region located on both sides of the central region. The central region is directly opposite the insulating portion, and the first edge region and the main tunnel junction are both located on the first side of the insulating portion, while the second edge region and the secondary tunnel junction are both located on the second side of the insulating portion. The top DBR layer is located in the central region and includes a first part and a second part. The first part is located on the first side of the insulating portion, and the second part is located on the second side of the insulating portion. A first positive electrode is located in the first edge region. A second positive electrode is located in the second edge region, and the top surface of the second part is located in the second part.

[0008] Furthermore, the main tunnel junction is located directly below the first section, and the secondary tunnel junction is located directly below the second section.

[0009] Furthermore, the bottom surface of the insulating portion is higher than the bottom surface of the lightly doped portion, and the bottom surface of the insulating portion is not higher than the top surface of the secondary tunnel junction and the top surface of the primary tunnel junction.

[0010] Furthermore, the bottom DBR layer, the first N-type confinement layer, the active region layer, and the P-type confinement layer located directly below the insulating part constitute a coupling region. The coupling region and the insulating part divide the vertical cavity surface-emitting laser into a main resonant cavity and a sub-resonant cavity. The light waves of the main resonant cavity and the light waves of the sub-resonant cavity are coupled in the coupling region to form a PPR effect in the main resonant cavity.

[0011] Furthermore, the first edge region includes a first injection region and a first non-injection region. The first injection region is adjacent to the central region, and the first non-injection region is located on the side of the first injection region away from the central region. The first positive electrode is located in the first injection region. The second edge region includes a second injection region and a second non-injection region. The second injection region is adjacent to the central region, and the second non-injection region is located on the side of the second injection region away from the central region. Except for a portion of the second positive electrode located on the top surface of the second part, the remaining second positive electrode is located in the second injection region.

[0012] Furthermore, the heavily doped portion and the lightly doped portion have the same doping type, but the doping concentration of the heavily doped portion is greater than that of the lightly doped portion.

[0013] Furthermore, the doping concentration of the heavily doped portion is greater than 1E. 19 cm -3 .

[0014] Furthermore, the reflectivity of the first part is less than that of the bottom DBR layer, and the reflectivity of the overall structure formed by the second part and the second positive electrode located on the top surface of the second part is greater than 99.9%.

[0015] Compared with the prior art, the present invention can achieve the following beneficial effects: The vertical-cavity surface-emitting laser (VCSEL) provided by this invention features an independent electrode structure, namely a second positive electrode, for the sub-resonant cavity. This makes the sub-resonant cavity an active, independent resonant cavity. By using an external current through the second positive electrode, the resonant frequency of the sub-resonant cavity can be precisely controlled, allowing the resonant frequency of the sub-resonant cavity to reach a specific resonance condition with that of the main resonant cavity. This achieves strong photon-photon resonance. Compared to the method where light waves leak from the main resonant cavity to the sub-resonant cavity, the sub-resonant cavity of this invention is also a gain cavity structure. Through active gain compensation, the loss of light waves traveling back and forth between the main and sub-resonant cavities can be compensated, increasing the intensity of light waves entering the main resonant cavity from the sub-resonant cavity, improving coupling efficiency, and thus increasing the intensity of the PPR effect. This effectively expands the transmission bandwidth of the VCSEL. Furthermore, setting a secondary resonant cavity on only one side of the main resonant cavity helps to reduce the transverse cavity width of the vertical cavity surface-emitting laser, thereby reducing the transmission loss caused by the transverse propagation of light waves in the transverse cavity. It also makes the secondary resonant cavity predominate in mode-stable longitudinal resonance, improving the controllability and stability of the resonant frequency of the secondary resonant cavity, which in turn helps to achieve a more stable PPR effect. This effectively solves the problems of low photon-photon resonance efficiency and poor stability, thereby effectively improving the -3dB bandwidth of the vertical cavity surface-emitting laser. Furthermore, compared to separating carrier transport between the main resonant cavity and the secondary resonant cavity based on oxide holes and ion implantation insulating layers, this invention uses a tunnel junction to achieve the separation of carrier transport between the main resonant cavity and the secondary resonant cavity. The fabrication method of the tunnel junction is simpler, easier to implement, and has stronger process controllability, making the fabrication of the high-speed vertical cavity surface-emitting laser provided by this invention easier. Attached Figure Description

[0016] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings: Figure 1 This is a schematic diagram of the structure of the vertical cavity surface-emitting laser described in an embodiment of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and do not constitute a limitation thereof.

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments of the present invention can be combined with each other.

[0019] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, 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 indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0021] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] refer to Figure 1This invention provides a vertical-cavity surface-emitting laser (VCSEL), comprising: a negative electrode layer 108, a substrate 100, a bottom DBR layer 101, a first N-type confinement layer 103, an active region layer 102, a P-type confinement layer 104, and a second N-type confinement layer stacked sequentially. The second N-type confinement layer includes a heavily doped portion, a lightly doped portion 106, and an insulating portion 111. The heavily doped portion includes a main tunnel junction 1051 and a secondary tunnel junction 1052 spaced apart on the surface of the P-type confinement layer 104. The lightly doped portion 106 is located on the remaining surface of the P-type confinement layer 104, and on the surfaces of the main tunnel junction 1051 and the secondary tunnel junction 1052. The top surface of the insulating portion 111 is flush with the top surface of the lightly doped portion 106, and the insulating portion 111 is located between the main tunnel junction 1051 and the secondary tunnel junction 1052. The top surface of the second N-type confinement layer is divided into a central region and a first edge region and a second edge region located on both sides of the central region. The central region is directly opposite the insulating portion 111, and the first edge region and the main tunnel junction 1051 are both located on the first side of the insulating portion 111, while the second edge region and the secondary tunnel junction 1052 are both located on the second side of the insulating portion 111. The top DBR layer 109 is located in the central region and includes a first part and a second part. The first part is located on the first side of the insulating portion 111, and the second part is located on the second side of the insulating portion 111. A first positive electrode 1071 is located in the first edge region. A second positive electrode 1072 is located in the second edge region, and the top surface of the second part is located in the second part.

[0023] The lower DBR layer 101, the first N-type confinement layer 103, the active region layer 102, and the P-type confinement layer 104 located directly below the insulating portion 111 constitute the coupling region 113. The coupling region 113 and the insulating portion 111 divide the vertical cavity surface-emitting laser into a main resonant cavity and a sub-resonant cavity. The main resonant cavity is responsible for laser lasing, and the sub-resonant cavity achieves frequency selection through electronic control. The light waves from the main resonant cavity and the light waves from the sub-resonant cavity are coupled in the coupling region 113 to form the PPR effect in the main resonant cavity, thereby effectively increasing the -3dB bandwidth range of the vertical cavity surface-emitting laser and achieving a higher data transmission rate.

[0024] It is understandable that the second positive electrode 1072 makes the sub-resonant cavity an active independent resonant cavity. By using an external current through the second positive electrode 1072, the resonant frequency of the sub-resonant cavity can be precisely controlled, so that the resonant frequency of the sub-resonant cavity and the resonant frequency of the main resonant cavity reach a specific resonance condition, and a strong photon-photon resonance can be achieved.

[0025] Furthermore, the main tunnel junction 1051 is located directly below the first part, and the secondary tunnel junction 1052 is located directly below the second part. This allows photons within the main resonant cavity to propagate along the shortest distance between the first part and the bottom DBR layer 101, reducing photon transmission loss within the main resonant cavity. Similarly, photons within the secondary resonant cavity can also propagate along the shortest distance between the second part and the bottom DBR layer 101, reducing photon transmission loss within the secondary resonant cavity.

[0026] Furthermore, the bottom surface of the insulating portion 111 is higher than the bottom surface of the lightly doped portion 106. It should be noted that the insulating portion 111 is typically formed by ion implantation. Since the bottom surface of the insulating portion 111 is higher than the bottom surface of the lightly doped portion 106, it is not necessary to implant the ions deeper, which helps reduce the difficulty of forming the insulating portion 111. In some embodiments, the bottom surface of the insulating portion 111 is not higher than the top surface of the secondary tunnel junction 1052 and the top surface of the primary tunnel junction 1051. The reason for this setting is that, with the bottom surface of the insulating portion 111 higher than the bottom surface of the lightly doped portion 106, if the bottom surface of the insulating portion 111 is higher than the top surface of the secondary tunnel junction 1052 and the top surface of the primary tunnel junction 1051, it may cause significant crosstalk between the charge carriers in the primary resonant cavity and the charge carriers in the secondary resonant cavity, increasing the difficulty of controlling the output beam of the vertical cavity surface-emitting laser. Therefore, setting the bottom surface of the insulating portion 111 to be no higher than the top surface of the secondary tunnel junction 1052 and the top surface of the primary tunnel junction 1051 is beneficial to reduce additional crosstalk beyond the PPR effect.

[0027] Furthermore, the first edge region includes a first injection region and a first non-injection region. The first injection region is adjacent to the central region, and the first non-injection region is located on the side of the first injection region away from the central region. The first positive electrode 1071 is located in the first injection region. The second edge region includes a second injection region and a second non-injection region. The second injection region is adjacent to the central region, and the second non-injection region is located on the side of the second injection region away from the central region. Except for the portion of the second positive electrode 1072 located on the top surface of the second part, the remaining second positive electrodes 1072 are located in the second injection region. Thus, both the first positive electrode 1071 and the second positive electrode 1072 have a certain distance from the edges on both sides of the vertical cavity surface-emitting laser, which helps to reduce leakage current.

[0028] In some embodiments, the substrate 100 can be a III-V group semiconductor material such as NGa, GaAs, InP, or GaSb, and the bottom DBR layer 101 can be a multi-period N-type DBR structure with alternating growth of high-refractive-index semiconductor materials and low-refractive-index semiconductor materials, with the thickness of each semiconductor material being one-quarter of the output laser wavelength; in some examples, the reflectivity of the bottom DBR layer 101 can be increased by increasing the number of periods, and the bottom DBR layer 101 typically has very high reflectivity and reflection bandwidth; the first N-type confinement layer 103 is used to achieve cavity length adjustment; the active region layer 102 is an active region structure with a multi-quantum-well structure, used to generate the optical gain required to form laser light; the P-type confinement layer 104, together with the first N-type confinement layer 103 and the bottom DBR layer 101, forms a PN junction, and is also used to achieve cavity length adjustment; the secondary tunnel junction 1052 and the main tunnel junction 1052 form a PN junction. All junctions 1051 are heavily doped, utilizing the Zener tunneling mechanism to achieve carrier tunneling under reverse current operation, thus limiting the path of the injected current. The lightly doped portion 106 is an N-type current extension layer. Due to its low doping concentration, it cannot achieve tunneling. Under reverse current, it exhibits unidirectional conduction characteristics of a PN junction with the P-type confinement layer 104. At the same time, the lightly doped portion 106 also participates in cavity length adjustment and position adjustment of various structures. The first positive electrode 1071 is the positive electrode of the main resonant cavity, the second positive electrode 1072 is the positive electrode of the secondary resonant cavity, and the negative electrode layer 108 is the common negative electrode of the main resonant cavity and the secondary resonant cavity. The top DBR layer 109 is a top dielectric film DBR mirror. The reflectivity of the top DBR layer 109 is lower than that of the bottom DBR layer 101. The insulating portion 111 is an ion implantation region used to achieve electrical isolation between the main resonant cavity and the secondary resonant cavity.

[0029] In some embodiments, the vertical cavity surface-emitting laser further includes an insulating layer 112 located on a first non-injection region and a second non-injection region. The insulating layer 112 is used to achieve electrical isolation and prevent leakage.

[0030] Furthermore, the heavily doped portion and the lightly doped portion 106 have the same doping type, but the doping concentration of the heavily doped portion is greater than that of the lightly doped portion 106. The lightly doped portion 106 and the P-type confinement layer 104 exhibit high resistance under reverse electrical bias, while the heavily doped portion can conduct normally under reverse bias.

[0031] Furthermore, the doping concentration of the heavily doped portion is greater than 1E. 19 cm -3 .

[0032] Furthermore, the reflectivity of the first part is less than that of the bottom DBR layer 101, which allows the laser generated by the main resonant cavity to be emitted from the top. The overall structure formed by the second part and the second positive electrode 1072 located on the top surface of the second part has a reflectivity greater than 99.9%. That is, the second part and the second positive electrode 1072 located on the top surface of the second part constitute a composite mirror with a reflectivity greater than 99.9%. This composite mirror and the bottom DBR layer 101 only provide optical wave feedback for the sub-resonant cavity. Since the mirrors at both ends of the sub-resonant cavity have extremely high reflectivity, no laser emission occurs from the sub-resonant cavity.

[0033] It should be noted that the vertical cavity surface-emitting laser provided by this invention is an NPN semiconductor structure. The first positive electrode 1071 and the negative electrode layer 108 are used to form the external current excitation of the main resonant cavity. The current injected from the first positive electrode 1071 tunnels through the main tunnel junction 1051 into the active region layer 102 to generate spontaneous emission. Then, the light wave is resonated through the first part and the bottom DBR layer 101 to form stimulated emission and generate laser light. The second positive electrode 1072 and the negative electrode layer 108 are used to form the external current excitation of the sub-resonant cavity. By adjusting the operating current of the sub-resonant cavity through the second positive electrode 1072, continuous tuning of the resonant wavelength in the sub-resonant cavity can be achieved. By precisely adjusting the injection current of the sub-resonant cavity, high-precision continuous tuning of the resonant wavelength of the sub-resonant cavity can be achieved. By actively adjusting the resonant frequency of the sub-resonant cavity, the frequency conditions for generating photon-photon resonance can be accurately achieved.

[0034] Understandably, during the design process, the coupling efficiency between the main resonant cavity and the secondary resonant cavity can be adjusted by controlling the width of the coupling region 113 and the depth of the insulating part 111, so that the light wave in the secondary resonant cavity couples with the light wave in the main resonant cavity in the coupling region 113 and enters the main resonant cavity to form the PPR effect.

[0035] In some embodiments, a bottom DBR layer 101 can be formed on an N-type InP substrate by epitaxial growth using MOCVD (Metal Organic Chemical Vapor Deposition). The bottom DBR layer 101 includes periodically arranged high-Al In atoms. x (Al y Ga 1-y ) 1-x As semiconductor material and In with low Al content x (Al y Ga 1-y ) 1-xAs a semiconductor material, the number of cycles can be 45, and the thickness of each layer is one-quarter of the output wavelength, ultimately forming an N-type DBR structure with a reflectivity greater than 99.5% as the bottom DBR layer 101; the first N-type confinement layer 103 and the active region layer 102 can be formed by epitaxial growth, and the active region layer 102 can be made of In x (Al y Ga 1-y ) 1-x As and In x (Al y Ga 1-y ) 1-x The expression is composed of As, where x can be in the range of 0.45 to 0.5 and y can be in the range of 0.25 to 0.3.

[0036] In some examples, insulation portion 111 uses H + It is formed by ion implantation.

[0037] In some examples, the top DBR layer 109 can be composed of alternating layers of Si and SiO2, and the thickness of the substrate 100 can be 130 μm.

[0038] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this utility model disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this utility model can be achieved, and this is not limited herein.

[0039] The specific embodiments described above do not constitute a limitation on the scope of protection of this utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A vertical-cavity surface-emitting laser, characterized in that, include: The following layers are stacked sequentially: a negative electrode layer, a substrate, a bottom DBR layer, a first N-type confinement layer, an active region layer, a P-type confinement layer, and a second N-type confinement layer. The second N-type confinement layer includes a heavily doped portion, a lightly doped portion, and an insulating portion. The heavily doped portion includes a main tunnel junction and a secondary tunnel junction arranged at intervals on the surface of the P-type confinement layer. The lightly doped portion is located on the remaining surface of the P-type confinement layer, as well as on the surfaces of the main tunnel junction and the secondary tunnel junction. The top surface of the insulating portion is flush with the top surface of the lightly doped portion and is located between the main tunnel junction and the secondary tunnel junction. The top surface of the second N-type confinement layer is divided into a central region and a first edge region and a second edge region located on either side of the central region. The central region is directly opposite the insulating portion, and both the first edge region and the main tunnel junction are located on the first side of the insulating portion. Both the second edge region and the secondary tunnel junction are located on the second side of the insulating portion. A top DBR layer is located in the central region. The top DBR layer includes a first portion and a second portion, wherein the first portion is located on a first side of the insulating portion and the second portion is located on a second side of the insulating portion. A first positive electrode is located in the first edge region; The second positive electrode is located in the second edge region and on the top surface of the second portion.

2. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The main tunnel junction is located directly below the first portion, and the secondary tunnel junction is located directly below the second portion.

3. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The bottom surface of the insulating portion is higher than the bottom surface of the lightly doped portion, and the bottom surface of the insulating portion is not higher than the top surface of the secondary tunnel junction and the top surface of the primary tunnel junction.

4. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The partial bottom DBR layer, the partial first N-type confinement layer, the partial active region layer, and the partial P-type confinement layer located directly below the insulating portion constitute a coupling region. The coupling region and the insulating portion divide the vertical cavity surface emitter laser into a main resonant cavity and a secondary resonant cavity. The light waves of the main resonant cavity and the light waves of the secondary resonant cavity are coupled in the coupling region to form a PPR effect in the main resonant cavity.

5. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The first edge region includes a first injection region and a first non-injection region. The first injection region is adjacent to the central region, and the first non-injection region is located on the side of the first injection region away from the central region. The first positive electrode is located in the first injection region. The second edge region includes a second injection region and a second non-injection region. The second injection region is adjacent to the central region, and the second non-injection region is located on the side of the second injection region away from the central region. Except for the portion of the second positive electrode located on the top surface of the second part, the remaining second positive electrode is located in the second injection region.

6. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The heavily doped portion and the lightly doped portion have the same doping type, and the doping concentration of the heavily doped portion is greater than that of the lightly doped portion.

7. The vertical-cavity surface-emitting laser according to claim 6, characterized in that, The doping concentration of the heavily doped portion is greater than 1E. 19 cm -3 .

8. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The reflectivity of the first part is less than that of the bottom DBR layer, and the reflectivity of the overall structure formed by the second part and the portion of the second positive electrode located on the top surface of the second part is greater than 99.9%.

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