A vertical cavity surface emitting laser and apparatus

Abstract

The utility model provides a kind of vertical cavity surface emitting laser and equipment, it is related to VCSEL technical field.Peripheral of micro mesa structure is annular groove with through active region and second DBR layer, the upper side of second DBR layer is provided with insulating layer, prevent current from the place outside micro mesa structure into epitaxial sheet;First electrode is provided with above insulating layer, current is introduced into the vicinity of micro mesa structure from solder pad;The size of the micro mesa structure is very small, it is difficult to do pattern on it, therefore cover transparent conductive film on the whole structure, respectively with the upper surface of micro mesa structure and the upper surface of first electrode contact, as the injection electrode of micro mesa structure, current can be guided to the area where micro mesa structure is and realizes current injection;Transparent conductive film is in the state of suspension at the area where annular groove is, thereby avoid the leakage problem caused by electrode contact side wall.

Description

Technical Field

[0001] This application relates to the field of VCSEL technology, and in particular to a vertical cavity surface-emitting laser and device. Background Technology

[0002] A vertical-cavity surface-emitting laser (VCSEL) is a semiconductor laser in which the emitted light is perpendicular to the substrate. Compared with traditional edge-emitting lasers, VCSELs have advantages such as small size, low cost, circularly symmetrical output beam, and easy two-dimensional arraying. They are now widely used in optical communication, facial recognition, lidar, and atomic sensing.

[0003] Oxidation-limited VCSELs are currently the most common type, such as... Figure 1 As shown, Figure 1 This is a schematic diagram of an oxide-confined VCSEL in the prior art. Current is injected from the top electrode 11, passes through the upper DBR (Distributed Bragg Reflector) layer 12, and enters the oxide confinement layer 13 and the active region 14. The outer edge region 131 of the oxide confinement layer 13 is insulating Al2O3, while the central region 132 is conductive Al. 0.98 Ga 0.02 As, this central region 132 is also known as the oxide aperture, where current is squeezed to the central oxide aperture. This process increases the current density in the active region 14, thereby reducing the threshold current of the VCSEL. Figure 1 The structure shown also includes a lower DBR layer 15 and a bottom electrode 16.

[0004] VCSELs have a large lateral dimension, which results in complex lateral modes. Therefore, how to design a single-mode emission VCSEL to address the multi-lateral mode problem in VCSELs is a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0005] In view of the above problems, this application provides a vertical-cavity surface-emitting laser (VCSEL) and its fabrication method and equipment, realizing a single-mode emission VCSEL. The specific solution is as follows:

[0006] A first aspect of this application provides a vertical-cavity surface-emitting laser, the vertical-cavity surface-emitting laser comprising:

[0007] Substrate;

[0008] A first DBR layer located on one side of the substrate, and a target structure located on the side of the first DBR layer facing away from the substrate; the target structure includes an active region and a second DBR layer stacked together, the active region being located between the second DBR layer and the first DBR layer;

[0009] An annular groove penetrating the target structure; the target structure includes a micro-platform structure located within the area enclosed by the annular groove, and an edge structure located outside the area enclosed by the annular groove;

[0010] An insulating layer and a first electrode are sequentially stacked on the side of the edge structure opposite to the substrate;

[0011] A transparent conductive film is located on the side of the target structure opposite to the substrate; the transparent conductive film is in contact with the upper surface of the micro mesa structure and the upper surface of the first electrode, respectively.

[0012] The laser emitted by the vertical cavity surface-emitting laser through the micro-mesa structure is in the fundamental mode.

[0013] Preferably, in the above-described vertical cavity surface-emitting laser, the vertical cavity surface-emitting laser further includes a second electrode located on the side of the substrate opposite to the first DBR layer.

[0014] Preferably, in the above-mentioned vertical cavity surface-emitting laser, the diameter of the micro-mesa structure ranges from 2μm to 4μm, including the endpoint value.

[0015] Preferably, in the above-mentioned vertical cavity surface-emitting laser, the annular groove is obtained by processing the target structure based on photolithography and etching processes.

[0016] Preferably, in the above-mentioned vertical cavity surface-emitting laser, the first DBR layer and the second DBR layer have different doping types; one DBR layer is P-type doped and the other DBR layer is N-type doped.

[0017] Preferably, in the above-mentioned vertical cavity surface-emitting laser, the area of ​​the orthographic projection pattern of the insulating layer on the plane where the substrate is located is A1, and the area of ​​the orthographic projection pattern of the first electrode on the plane where the substrate is located is A2.

[0018] Where A1 > A2.

[0019] Preferably, in the above-mentioned vertical cavity surface-emitting laser, the thickness of the substrate ranges from 100 μm to 600 μm, including the endpoint values.

[0020] A second aspect of this application provides a method for fabricating a vertical-cavity surface-emitting laser (VCSEL), the method comprising:

[0021] Provide a substrate;

[0022] A first DBR layer is formed on one side of the substrate, and a target structure is formed on the side of the first DBR layer facing away from the substrate; the target structure includes an active region and a second DBR layer stacked together, the active region being located between the second DBR layer and the first DBR layer;

[0023] The target structure is subjected to photolithography and etching to form an annular trench that runs through the target structure; the target structure includes a micro-mesa structure located within the area enclosed by the annular trench, and an edge structure located outside the area enclosed by the annular trench;

[0024] An insulating layer and a first electrode are sequentially formed on the side of the edge structure opposite to the substrate;

[0025] A transparent conductive film is formed on the side of the target structure away from the substrate; the transparent conductive film is in contact with the upper surface of the micro mesa structure and the upper surface of the first electrode, respectively; wherein the laser emitted by the vertical cavity surface emission laser through the micro mesa structure is in the fundamental mode.

[0026] Preferably, in the above-described method for fabricating a vertical-cavity surface-emitting laser, the step of forming a transparent conductive thin film on the side of the target structure opposite to the substrate includes:

[0027] A transparent conductive film is formed on the substrate;

[0028] A support layer is formed on the side of the transparent conductive film opposite to the substrate;

[0029] Remove the substrate;

[0030] The transparent conductive film with the support layer is transferred to the side of the target structure away from the substrate, so that the transparent conductive film contacts the upper surface of the micro mesa structure and the upper surface of the first electrode, respectively.

[0031] Remove the support layer.

[0032] A third aspect of this application provides an apparatus comprising any of the above-described vertical cavity surface-emitting lasers.

[0033] Using the above technical solution, this application provides a vertical-cavity surface-emitting laser and its fabrication method and equipment. The micro-mesa structure is surrounded by annular trenches penetrating the active region and the second DBR layer, thereby separating the central micro-mesa structure from the surrounding edge structures. The area containing the edge structures outside the annular trenches is the electrode region, where an insulating layer is disposed above the second DBR layer to prevent current from entering the epitaxial wafer from outside the micro-mesa structure. A first electrode is disposed above the insulating layer to introduce current from the pads into the vicinity of the micro-mesa structure. To ensure that the laser emitted by the vertical-cavity surface-emitting laser through the micro-mesa structure is in the fundamental mode, the micro-mesa... The mesa structure is very small, making it difficult to create patterns on it. Therefore, a transparent conductive film is placed over the entire structure. This transparent conductive film contacts both the upper surface of the micro-mesa structure and the upper surface of the first electrode, serving as the injection electrode for the micro-mesa structure. It guides current to the area where the micro-mesa structure is located and injects current. Due to the annular groove, the transparent conductive film is suspended in the area where the annular groove is located, thus avoiding leakage problems caused by the electrode contacting the sidewall. Furthermore, the high thermal conductivity of the transparent conductive film can enhance the heat dissipation of the single-mode VCSEL, improving its working performance and lifespan. Attached Figure Description

[0034] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0035] Figure 1 This is a schematic diagram of the structure of an oxidation-restricted VCSEL in the prior art;

[0036] Figure 2 This is a schematic diagram of the spatial distribution of the VCSEL mode;

[0037] Figure 3 A three-dimensional structural diagram of a vertical cavity surface-emitting laser provided for an embodiment of this utility model;

[0038] Figure 4 A cross-sectional schematic diagram of a vertical cavity surface-emitting laser provided for an embodiment of this utility model;

[0039] Figure 5 A schematic flowchart illustrating a method for fabricating a vertical cavity surface-emitting laser according to an embodiment of this utility model;

[0040] Figures 6-16 for Figure 5 A partial structural schematic diagram corresponding to the preparation method shown. Detailed Implementation

[0041] The embodiments of this application are described below with reference to the accompanying drawings. The terminology used in the implementation section of this application is only for explaining specific embodiments and is not intended to limit the application. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0042] Based on the background information, VCSELs have a relatively large lateral dimension, which results in complex lateral modes. The lateral modes of VCSELs can be represented by linear polarization mode theory, where LP... 01 The mode is the fundamental mode, LP 11 LP 21 and LP 02 These are higher-order modes. Higher-order modes can cause VCSELs to exhibit phenomena such as wavelength blue shift, reduced side-mode suppression ratio, and increased divergence angle. Therefore, it is important to maintain VCSELs with only LP modes. 01 Mode emission is key to improving the beam quality of VCSELs.

[0043] A single-mode (also known as a single transverse mode) VCSEL emits light containing only the fundamental mode (LP). 01 The mode (also known as the fundamental transverse mode) has high beam quality.

[0044] Reducing the aperture of the oxide aperture is a fundamental method for achieving single-mode emission in VCSELs. The refractive index distribution of oxide-confined VCSELs is similar to that of optical fibers. When the diameter of the oxide aperture is reduced to approximately 3.5 μm, only the fundamental mode is allowed within the waveguide, thus enabling single-mode emission. Another important method for achieving single-mode emission is to increase the loss of higher-order modes, preventing their lasing. Different modes are distributed at different locations within the waveguide, such as... Figure 2 As shown, Figure 2 This diagram illustrates the spatial distribution of VCSEL modes. The peak of the fundamental mode is located at the waveguide center, while the peaks of higher-order modes are located at the waveguide edges. Therefore, special structural designs can be made to increase the loss in the higher-order mode region. For example, surface relief structures increase the mirror loss in the higher-order mode region by creating a reflection layer, while Zn diffusion disrupts the resonant structure of the higher-order mode region through alloying, thereby increasing the absorption rate in that region. Both methods achieve single-mode emission of the VCSEL by increasing the loss of higher-order modes.

[0045] However, for small-aperture VCSELs, the diameter of the oxide pores needs to be reduced to around 3 μm, which is difficult to achieve stably in the process. During wet nitrogen oxidation, the oxidation results in different regions of the VCSEL epitaxial wafer will vary slightly. Areas with excessively small pores cannot emit light normally, while areas with excessively large pores cannot effectively confine higher-order modes, leading to a decrease in yield. Furthermore, the pore size is difficult to determine directly. Since the oxide pores are deeply buried below the upper DBR layer, the upper DBR layer 12 needs to be destroyed to observe the actual pore size, making the fabrication process of small-aperture VCSELs very complex. Techniques for destroying the upper DBR layer 12 include, but are not limited to, etching techniques and FIB (Focused Ion Beam) techniques.

[0046] Furthermore, surface embossing and Zn diffusion, in order to suppress higher-order modes, require the introduction of additional losses at the waveguide edges, which results in the loss of most of the current. Figure 1 As can be seen from the structure shown, although the current is limited by the oxide pores, the current density inside the oxide pores is not uniform. The current tends to be transported along the shortest path, and a current congestion effect occurs at the edge of the oxide pores, where the current density is higher.

[0047] In summary, traditional VCSELs require the introduction of losses at the waveguide edges, which prevents light emission in high current density regions and severely impacts the efficiency of VCSELs.

[0048] Based on this, this utility model provides a vertical-cavity surface-emitting laser (VCSEL) and its fabrication method and equipment. Addressing the multi-transverse-mode problem inherent in existing VCSELs, a micro-mesa structure is etched to allow only the fundamental transverse mode to exist, thereby achieving single-mode emission of the VCSEL. Current injection into the micro-mesa structure is achieved through a transparent conductive film. For example, a transparent conductive film, typically a two-dimensional material such as graphene, is used to cover the surface of the mesa structure as a transparent electrode, enabling current injection without affecting beam emission. Simultaneously, the high thermal conductivity of the transparent conductive film enhances heat dissipation for the single-mode VCSEL, improving its performance and lifespan.

[0049] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] It should be noted that the directional terms appearing in this utility model are based on the relative positional relationships shown in the accompanying drawings and should not be taken as absolute limitations on this application.

[0051] refer to Figure 3 , Figure 3A three-dimensional structural schematic diagram of a vertical cavity surface-emitting laser provided for an embodiment of this utility model, wherein... Figure 3 (a) represents a schematic diagram of the overall three-dimensional structure. Figure 3 (b) shows a schematic diagram of the three-dimensional structure in cross-sectional state; Reference Figure 4 , Figure 4 This is a cross-sectional schematic diagram of a vertical cavity surface-emitting laser (VCSEL) provided in an embodiment of the present invention. The VCSEL provided in this embodiment of the present invention includes: a substrate 21.

[0052] A first DBR layer 22 located on one side of the substrate 21, and a target structure located on the side of the first DBR layer 22 away from the substrate 21; the target structure includes an active region 23 and a second DBR layer 24 stacked together, the active region 23 being located between the second DBR layer 24 and the first DBR layer 22.

[0053] An annular groove 25 penetrating the target structure; the target structure includes a micro-platform structure 26 located within the area enclosed by the annular groove 25, and an edge structure 27 located outside the area enclosed by the annular groove 25.

[0054] An insulating layer 28 and a first electrode 29 are located on the side of the edge structure 27 away from the substrate 21 and are stacked in sequence.

[0055] A transparent conductive film 30 is located on the side of the target structure opposite to the substrate 21; the transparent conductive film 30 is in contact with the upper surface of the micro mesa structure 26 and the upper surface of the first electrode 29, respectively.

[0056] The laser emitted by the vertical cavity surface-emitting laser through the micro-mesa structure 26 is in the fundamental mode.

[0057] like Figure 3 and Figure 4 As shown, the vertical cavity surface-emitting laser further includes a second electrode 31 located on the side of the substrate 21 opposite to the first DBR layer 22. The first electrode 29 is often referred to as the top electrode, and the second electrode 31 is often referred to as the bottom electrode.

[0058] Specifically, in this embodiment of the invention, the substrate 21 includes, but is not limited to, a GaAs substrate. The thickness of the substrate 21 ranges from 100 μm to 600 μm, including the endpoint values. The first DBR layer 22 has approximately 40 stacked layers, and the second DBR layer 24 has approximately 20 stacked layers. The first DBR layer 22 and the second DBR layer 24 have different doping types, with one DBR layer being P-type doped and the other being N-type doped. Optionally, when the first DBR layer 22 is N-type doped and the second DBR layer 24 is P-type doped, the vertical-cavity surface-emitting laser is a right-mounted structure. Optionally, when the first DBR layer 22 is P-type doped and the second DBR layer 24 is N-type doped, the vertical-cavity surface-emitting laser is a flip-chip structure. The active region 23 can be composed of multiple quantum wells.

[0059] In the vertical-cavity surface-emitting laser provided in this embodiment, the micro-mesa structure 26 is surrounded by annular trenches 25 penetrating the active region 23 and the second DBR layer 24, thereby separating the central micro-mesa structure 26 from the surrounding edge structures 27. The area of ​​the edge structures 27 outside the annular trenches 25 is the electrode region, in which an insulating layer 28 is disposed above the second DBR layer 24 to prevent current from entering the epitaxial wafer from outside the micro-mesa structure 26. A first electrode 29 is disposed above the insulating layer 28 to introduce current from the pads into the vicinity of the micro-mesa structure 26. In order to ensure that the laser emitted by the vertical-cavity surface-emitting laser through the micro-mesa structure 26 is in the fundamental mode and to achieve lateral mode limitation, the size of the micro-mesa structure 26 is very small. The diameter of the micro-mesa structure 26 ranges from 2μm to 4μm, including the endpoints, making it difficult to pattern. Therefore, a transparent conductive film 30 is covered over the entire structure. This transparent conductive film 30 contacts both the upper surface of the micro-mesa structure 26 and the upper surface of the first electrode 29, serving as the injection electrode for the micro-mesa structure 26. It guides current to the area where the micro-mesa structure 26 is located and injects current. Due to the annular groove 25, the transparent conductive film 30 is suspended in the area where the annular groove 25 is located, thereby avoiding leakage problems caused by the electrode contacting the sidewall. Furthermore, the high thermal conductivity of the transparent conductive film 30 can enhance the heat dissipation of the single-mode VCSEL, improving its working performance and lifespan.

[0060] The annular groove 25 is obtained by processing the target structure using photolithography and etching processes. The size of the micro-mesa structure 26 is controlled through photolithography and etching processes, ensuring that only the fundamental mode exists within the corresponding size of the micro-mesa structure 26. For example, the diameter of the micro-mesa structure 26 is in the range of 2μm-4μm, including the endpoints. This means that the technical solution of this application can control the emitted laser mode through photolithography and etching processes rather than oxidation. The precision of photolithography and etching processes far exceeds that of oxidation processes; therefore, this structure can be fabricated into a single-mode VCSEL using a simple process flow.

[0061] Specifically, a micro-mesa structure 26 is obtained through photolithography and etching processes. The small size of the micro-mesa structure 26 allows for a high internal current density, while its size only allows for the existence of the fundamental mode. The size of the micro-mesa structure 26 is defined by photolithography and etching processes, which have a precision far exceeding that of oxidation processes. Therefore, this structure achieves a mode-limiting effect similar to that of small-aperture VCSELs while avoiding the need for small-aperture oxidation processes. The principle of mode control is similar to that of small-aperture VCSELs, but it avoids the complex oxidation processes in small-aperture VCSELs. Compared to surface relief and Zn diffusion structures, it avoids introducing additional losses, and its higher efficiency has been confirmed by theory and experimental verification.

[0062] Furthermore, considering that current injection into the micro-mesa structure 26 is a major challenge, since the electrodes are opaque, a light-emitting hole needs to be opened at the center of the top electrode of a traditional VCSEL. However, the micro-mesa structure 26 is very small and difficult to further pattern. Therefore, in this embodiment of the invention, a transparent conductive film 30 (such as graphene or other transparent conductive films with high conductivity and light transmittance) is used as the injection electrode. The graphene film has high conductivity and light transmittance, and can cover the surface of the micro-mesa structure 26 for current injection without affecting light emission. The graphene film in the area where the annular groove 25 is located can be in a suspended state, so that the current enters the graphene electrode from the first electrode 29, and enters the surface of the micro-mesa structure 26 through the "graphene bridge" at the annular groove 25 to complete the current injection. At the same time, the high thermal conductivity of the transparent conductive film 30 can also enhance the heat dissipation of the single-mode VCSEL, improve the working performance and service life of the single-mode VCSEL.

[0063] In an optional embodiment of this utility model, the area of ​​the orthographic projection pattern of the insulating layer 28 on the plane where the substrate 21 is located is A1, and the area of ​​the orthographic projection pattern of the first electrode 29 on the plane where the substrate 21 is located is A2.

[0064] Where A1 > A2.

[0065] Specifically, in this embodiment of the invention, the size of the first electrode 29 is slightly smaller than the size of the insulating layer 28, so as to avoid the first electrode 29 covering the sidewall of the edge structure 27, which would cause current to be injected into the epitaxial wafer area other than the micro mesa structure 26, affecting the working performance of the vertical cavity surface emitter laser.

[0066] Based on the above embodiments of this utility model, another embodiment of this utility model also provides a method for fabricating a vertical cavity surface-emitting laser, see reference. Figure 5 , Figure 5 This is a schematic flowchart illustrating a method for fabricating a vertical-cavity surface-emitting laser (VCSEL) according to an embodiment of the present invention. The method for fabricating a VCSEL according to an embodiment of the present invention includes:

[0067] S101: As Figure 6 As shown, a substrate 21 is provided.

[0068] Specifically, in this step, the substrate 21 includes, but is not limited to, a GaAs substrate.

[0069] S102: As Figure 7 As shown, a first DBR layer 22 is formed on one side of the substrate 21, and a target structure is formed on the side of the first DBR layer 22 away from the substrate 21; the target structure includes an active region 23 and a second DBR layer 24 stacked together, the active region 23 being located between the second DBR layer 24 and the first DBR layer 22.

[0070] Specifically, this step includes, but is not limited to, using MOCVD (Metal-organic Chemical Vapor Deposition). (Chinese name: Metal-Organic Chemical Vapor Deposition) A layered epitaxial growth process is performed on a substrate 21, consisting of a first DBR layer 22, an active region 23, and a second DBR layer 24. The first DBR layer 22 has approximately 40 stacked layers, and the second DBR layer 24 has approximately 20 stacked layers. The first DBR layer 22 and the second DBR layer 24 have different doping types, with one DBR layer being P-type doped and the other being N-type doped. Optionally, when the first DBR layer 22 is N-type doped and the second DBR layer 24 is P-type doped, the fabricated vertical-cavity surface-emitting laser is a right-mounted structure. Optionally, when the first DBR layer 22 is P-type doped and the second DBR layer 24 is N-type doped, the vertical-cavity surface-emitting laser is a flip-chip structure. The active region 23 can be composed of multiple quantum wells.

[0071] It should be noted that, in this embodiment of the present invention, the stacked structure consisting of the active region 23 and the second DBR layer 24 is defined as the target structure.

[0072] S103: As Figure 8 As shown, the target structure is subjected to photolithography and etching to form an annular trench 25 that runs through the target structure; the target structure includes a micro-mesa structure 26 located within the area enclosed by the annular trench 25, and an edge structure 27 located outside the area enclosed by the annular trench 25.

[0073] Specifically, in this step, based on the required size of the micro mesa structure 26, the surface of the second DBR layer 24 facing away from the substrate 21 is patterned by photolithography, and then annular trenches 25 are etched using ICP (Inductively Coupled Plasma) to form the micro mesa structure 26, with the etching depth at least penetrating the active region 23; in this embodiment of the present invention, the diameter of the micro mesa structure 26 formed is in the range of 2μm-4μm, including the endpoint value.

[0074] S104: As Figure 9 and Figure 10 As shown, an insulating layer 28 and a first electrode 29 are sequentially formed on the side of the edge structure 27 opposite to the substrate 21.

[0075] Specifically, in this step, such as Figure 9 As shown, this includes, but is not limited to, using PECVD (Plasma Enhanced Chemical Vapor Deposition) to grow an insulating layer 28 of insulating materials such as silicon nitride on the surface of the edge structure 27, so as to achieve insulation of the area other than the micro mesa structure 26 and the annular trench 25.

[0076] like Figure 10 As shown, the method includes, but is not limited to, fabricating the first electrode 29 using electron beam evaporation and stripping. The first electrode 29 is located above the insulating layer 28. The size of the first electrode 29 is slightly smaller than the size of the insulating layer 28 to avoid the first electrode 29 covering the sidewall of the edge structure 27, which would cause current injection into the epitaxial wafer region other than the micro mesa structure 26 and affect the working performance of the vertical cavity surface emission laser.

[0077] Furthermore, before forming the transparent conductive thin film 30, the method for fabricating the vertical-cavity surface-emitting laser provided in this embodiment of the invention further includes:

[0078] like Figure 11As shown, the substrate 21 is thinned to a thickness ranging from 100 μm to 600 μm, including endpoints, for example, to a thickness of 100 μm. Based on Figure 10 and Figure 11 In terms of the structure shown, there exists a relationship L1 < L2.

[0079] like Figure 12 As shown, a second electrode 31 is formed on the side of the substrate 21 opposite to the first DBR layer 22.

[0080] Specifically, this step includes, but is not limited to, fabricating the second electrode 31 using electron beam evaporation, thus completing the fabrication of the basic structure of the vertical cavity surface-emitting laser.

[0081] S105: As Figure 4 As shown, a transparent conductive film 30 is formed on the side of the target structure away from the substrate 21; the transparent conductive film 30 is in contact with the upper surface of the micro mesa structure 26 and the upper surface of the first electrode 29 respectively; wherein, the laser emitted by the vertical cavity surface emission laser through the micro mesa structure 26 is in the fundamental mode.

[0082] One optional embodiment in which a transparent conductive film 30 is formed on the side of the target structure opposite to the substrate 21 is as follows:

[0083] like Figure 13 As shown, a transparent conductive film 30 is formed on a substrate 32; optionally, graphene is grown on a copper foil using MOCVD.

[0084] like Figure 14 As shown, a support layer 33 is formed on the side of the transparent conductive film 30 away from the substrate 32; optionally, PMMA (polymethyl methacrylate) is spin-coated onto the graphene surface as the support layer 33.

[0085] like Figure 15 As shown, the substrate 32 is removed; optionally, the copper foil, graphene, and PMMA structure are suspended on the surface of a copper etching solution (such as copper sulfate-hydrochloric acid) to remove the copper foil, with the copper foil in contact with the etching solution. After removing the copper foil, the graphene and PMMA structure is transferred to deionized water for cleaning.

[0086] like Figure 16As shown, the transparent conductive film 30 with the support layer 33 is transferred to the side of the target structure away from the substrate 21, so that the transparent conductive film 30 contacts the upper surface of the micro-mesa structure 26 and the upper surface of the first electrode 29, respectively; optionally, the graphene or PMMA structure is transferred to Figure 12 On the surface of the structure shown, graphene connects the first electrode 29 to the micro-mesa structure 26 and is suspended in the region where the annular groove 25 is located.

[0087] like Figure 4 As shown, the support layer 33 is removed; optionally, PMMA on the graphene surface is removed by soaking in acetone, and after rapid annealing, the fabrication of the vertical cavity surface-emitting laser of this embodiment is completed.

[0088] The annular groove 25 is obtained by processing the target structure using photolithography and etching processes. The size of the micro-mesa structure 26 is controlled through photolithography and etching processes, ensuring that only the fundamental mode exists within the corresponding size of the micro-mesa structure 26. For example, the diameter of the micro-mesa structure 26 is in the range of 2μm-4μm, including the endpoints. This means that the technical solution of this application can control the emitted laser mode through photolithography and etching processes rather than oxidation. The precision of photolithography and etching processes far exceeds that of oxidation processes; therefore, this structure can be fabricated into a single-mode VCSEL using a simple process flow.

[0089] Based on the above embodiments of the present invention, another embodiment of the present invention also provides a device, the device including the vertical cavity surface-emitting laser described in the above embodiments.

[0090] Specifically, this vertical-cavity surface-emitting laser can be applied to mobile phone screen-off and facial recognition, for example, to mobile phone sensors to achieve contactless operation.

[0091] This vertical cavity surface-emitting laser can be applied to lidar, such as in autonomous driving, robotics, and drones, to achieve obstacle detection and distance measurement; it can also be applied to vehicle sensors, such as health monitoring components including blood oxygen detection and heart rate monitoring.

[0092] This vertical-cavity surface-emitting laser can be used in data center optical interconnects as a core light source, supporting short-distance high-speed data transmission and meeting the needs of cloud computing.

[0093] This vertical cavity surface-emitting laser can be applied to industrial automation equipment for applications such as precision position detection and motor control, thereby improving the intelligence level of the equipment.

[0094] This vertical-cavity surface-emitting laser can be applied to biomedical imaging, specifically optical coherence tomography (OCT), to achieve high-resolution biological tissue imaging.

[0095] This vertical-cavity surface-emitting laser can be used in quantum precision measurement as a core light source in high-precision measurement equipment such as quantum magnetometers and gyroscopes.

[0096] The above provides a detailed description of a vertical cavity surface-emitting laser and its fabrication method and equipment provided by this utility model. Specific examples have been used to illustrate the principle and implementation of this utility model. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.

[0097] It should be noted that each embodiment in this specification focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other.

[0098] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that elements inherent to a process, method, article, or apparatus that comprises a list of elements, or elements inherent to such processes, methods, articles, or apparatus, are also included. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0099] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A vertical-cavity surface-emitting laser, characterized in that, The vertical-cavity surface-emitting laser includes: Substrate; A first DBR layer located on one side of the substrate, and a target structure located on the side of the first DBR layer facing away from the substrate; the target structure includes an active region and a second DBR layer stacked together, the active region being located between the second DBR layer and the first DBR layer; An annular groove penetrating the target structure; the target structure includes a micro-platform structure located within the area enclosed by the annular groove, and an edge structure located outside the area enclosed by the annular groove; An insulating layer and a first electrode are sequentially stacked on the side of the edge structure opposite to the substrate; A transparent conductive film is located on the side of the target structure opposite to the substrate; the transparent conductive film is in contact with the upper surface of the micro mesa structure and the upper surface of the first electrode, respectively. The laser emitted by the vertical cavity surface-emitting laser through the micro-mesa structure is in the fundamental mode.

2. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The vertical-cavity surface-emitting laser also includes: The second electrode is located on the side of the substrate opposite to the first DBR layer.

3. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The diameter of the micro-mesa structure ranges from 2μm to 4μm, including the endpoint values.

4. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The annular groove is obtained by processing the target structure using photolithography and etching processes.

5. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The first DBR layer and the second DBR layer have different doping types; one DBR layer is P-type doped and the other DBR layer is N-type doped.

6. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The area of ​​the orthographic projection of the insulating layer onto the plane of the substrate is A1, and the area of ​​the orthographic projection of the first electrode onto the plane of the substrate is A2. Where A1 > A2.

7. The vertical-cavity surface-emitting laser according to claim 1, characterized in that, The thickness of the substrate ranges from 100μm to 600μm, including the endpoint values.

8. A device, characterized in that, The device includes the vertical cavity surface-emitting laser according to any one of claims 1-7.

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