Laser radar scanning transmitting device and preparation method thereof

Abstract

The invention provides a laser radar scanning transmitting device and a preparation method thereof. The laser radar scanning transmitting device comprises a substrate, a plurality of circular-truncated-cone-shaped vertical cavity surface emitting lasers and a primary carrier plate. The circular-truncated-cone-shaped vertical cavity surface emitting lasers are arranged on the substrate in a two-dimensional array. The substrate is arranged in the middle area of the primary support plate, and the primary support plate is connected with the plurality of circular-truncated-cone-shaped vertical cavity surface emitting lasers through a plurality of wires; wherein the top of each circular-truncated-cone-shaped vertical-cavity surface-emitting laser is an upper contact layer, the upper surface of each upper contact layer is photoetched to form a strip-shaped grating, and at least one of the period, the duty ratio, the depth and the relative rotation angle of the strip-shaped grating on each circular-truncated-cone-shaped vertical-cavity surface-emitting laser is different, so that two-dimensional laser lattices with different emergent angles are formed.

Description

Technical Field

[0001] The present disclosure relates to the technical field of photon and optoelectronic device design, and particularly to a lidar scanning emission device and a preparation method thereof. Background Art

[0002] Lidar is a radar operating in the optical frequency band. Similar to the working principle of microwave radar, it uses electromagnetic waves in the optical frequency band to first emit detection signals to a target, and then compares the received signals in the same band with the emitted signals to obtain information such as the position (distance, azimuth, and altitude) and motion state (speed, attitude) of the target. Near-infrared lidar has the characteristics of high resolution, eye safety, strong penetration, easy integration, all-solid state, and high scanning speed, and has extremely important application prospects in civil fields such as unmanned driving, robots, drones, intelligent education, intelligent medical care, and digital cities.

[0003] The spatial scanning methods of lidar can be divided into non-scanning systems and scanning systems. Among them, the scanning system can select methods such as mechanical scanning, electrical scanning, and binary optical scanning. The non-scanning imaging system uses a multi-element detector, has a longer operating distance, and is different from the unit detection of scanning imaging in the detection system, which can reduce the volume and weight of the device. Currently, the scanning working system is mostly used. Semiconductor diode lasers, with their small size, light weight, firmness and reliability, high repetition frequency, potential low cost, and the characteristics of using uncooled high-sensitivity avalanche photodiode (APD) detectors, have become the preferred light sources for small lidars.

[0004] Typical solid-state laser radars generally include phased array lidars and Flash lidars based on charge-coupled device (CCD) pixel-level time-of-flight measurement. For phased array lidars, the emission angle of the laser beam is controlled by adjusting the phase of the beam and the wavelength of the laser, and the scanning of the laser beam is realized. Since it is necessary to couple the laser beam of the laser into the antenna array and split the beam entering the antenna array, the emission power of the antenna is much lower than the power of the laser light source, so its light utilization rate is very low. For Flash lidars, a laser beam is expanded and emitted to cover a large area of laser, and imaging is received by a high-sensitivity area array detector, which also results in its inability to perform long-distance detection. Therefore, improving the light utilization rate and long-distance detection ability of the lidar scanning emission device has become an extremely challenging task. Summary of the Invention

[0005] In view of the above problems, the present invention provides a lidar scanning emission device and a preparation method thereof to solve problems such as low light utilization rate and poor long-distance detection ability of traditional lidar emission devices.

[0006] One aspect of the present disclosure provides a lidar scanning emission device, including: a substrate; a plurality of frustum-shaped vertical cavity surface emitting lasers arranged in a two-dimensional array on the substrate; a primary carrier board, the substrate is disposed in the middle region of the primary carrier board, and the primary carrier board is connected to the plurality of frustum-shaped vertical cavity surface emitting lasers through a plurality of wires; wherein, the top of each frustum-shaped vertical cavity surface emitting laser is an upper contact layer, and a strip grating is formed by photolithography on the upper surface of the upper contact layer, and at least one of the period, duty cycle, depth, and relative rotation angle of the strip gratings on each frustum-shaped vertical cavity surface emitting laser is different from each other to form a two-dimensional laser dot matrix with different emission angles.

[0007] Optionally, each frustum-shaped vertical cavity surface emitting laser includes: a lower Bragg reflector disposed on the substrate; a transition layer disposed on the lower Bragg reflector; an active layer disposed on the transition layer for generating laser; an upper Bragg reflector disposed on the active layer, and the upper Bragg reflector and the lower Bragg reflector generate laser oscillation by reflecting the laser in the active layer.

[0008] Optionally, each frustum-shaped vertical cavity surface emitting laser is etched with a plurality of strip grooves in the height direction.

[0009] Optionally, a first carrier board metal layer and a second carrier board metal layer are disposed on the primary carrier board, wherein the first carrier board metal layer is disposed at the four corners of the substrate; the second carrier board metal layer is disposed at the bottom of the substrate and in the middle of two adjacent first carrier board metal layers; the first carrier board metal layer and the second carrier board metal layer are separated by a trench.

[0010] Optionally, the lidar scanning emission device further includes: an upper metal layer covering the side walls of the frustum-shaped vertical cavity surface emitting lasers and between two adjacent frustum-shaped emitting lasers, the upper contact layer is electrically connected to the upper contact layer, the upper metal layer is electrically connected to the upper contact layer, and the upper metal layer is electrically connected to the first carrier board metal layer through the wire; a lower metal layer disposed between the substrate and the second carrier board metal layer for cooperating with the upper metal layer to inject current into the frustum-shaped vertical cavity surface emitting lasers.

[0011] Optionally, a transparent insulating layer is provided on the surface of the strip groove, the side wall of the frustum-shaped vertical cavity surface emitting laser, and between two adjacent frustum-shaped vertical cavity surface emitting lasers, the upper metal layer covers the transparent insulating layer, the transparent insulating layer has pores reserved on the upper contact layer, and the upper metal layer is connected to the upper contact layer through the pores.

[0012] Optionally, the upper metal layer is provided with a light outlet on the top surface of the frustum-shaped vertical cavity surface emitting laser.

[0013] Optionally, the lidar scanning emission device further includes: at least one electronic control switch, which is connected to the plurality of wires and is used to control the power supply of each frustum-shaped vertical cavity surface emitting laser.

[0014] Optionally, the diameter of each frustum-shaped vertical cavity surface emitting laser is 10 μm to 100 μm, the height is 2 μm to 10 μm, and the period of the strip grating is 1 μm to 30 μm.

[0015] Another aspect of the present disclosure provides a method for manufacturing the above-mentioned lidar scanning emission device, including: growing a substrate on a primary carrier; growing and etching a frustum-shaped epitaxial wafer on the substrate to obtain a plurality of frustum-shaped structures arranged in a two-dimensional array; etching a plurality of strip grooves at uniform intervals along the height direction of each frustum-shaped structure to form a strip grating, and at least one of the period, duty cycle, depth, and relative rotation angle of the strip grating on each frustum-shaped structure is different from each other.

[0016] The above-mentioned at least one technical solution adopted in the embodiments of the present disclosure can achieve the following beneficial effects:

[0017] 1. Each frustum-shaped vertical cavity surface emitting laser is suitable for measuring at a certain angle, and does not require a complex optical path, increasing the light source utilization rate;

[0018] 2. By adjusting the period, duty cycle, and depth of the strip grating, the lasers emitted by multiple frustum-shaped vertical cavity surface emitting lasers can be emitted at specific angles respectively, and can be used to scan objects within a certain distance, and the position of the object can be determined by the reflection of the object;

[0019] 3. The multiple frustum-shaped vertical cavity surface emitting lasers provided by the present disclosure are arranged in a two-dimensional array on the substrate. By adjusting the relative rotation angle of the strip grating on each frustum-shaped vertical cavity surface emitting laser, a laser dot matrix arranged in a two-dimensional array can be obtained. Description of the Drawings

[0020] To more fully understand the present disclosure and its advantages, reference will now be made to the following description in conjunction with the accompanying drawings, where:

[0021] Figure 1 A perspective view of a lidar scanning emission device provided by an embodiment of the present disclosure is schematically shown;

[0022] Figures 2a - 2j A flowchart of a method for manufacturing a lidar scanning emission device provided by an embodiment of the present disclosure is schematically shown;

[0023] Explanation of the figure markings: 1-substrate; 2-lower Bragg reflector; 3-transition layer; 4-active layer; 5-upper Bragg reflector; 6-upper contact layer; 7-upper metal layer; 71-first metal layer; 72-second metal layer; 8-lower metal layer; 91-strip groove; 92-strip grating; 10-first transparent insulating layer; 11-second transparent insulating layer; 12-primary carrier; 121-first carrier metal layer; 122-second carrier metal layer; 13-wire. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0025] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0026] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0027] Figure 1 A stereoscopic diagram of a laser radar scanning and transmitting device provided by an embodiment of the present disclosure is schematically shown.

[0028] In one aspect of the embodiments of the present disclosure, a laser radar scanning and transmitting device is provided, such as Figure 1 As shown, it includes a substrate 1, a primary carrier plate 12 and a plurality of truncated cone-shaped vertical cavity surface emitting lasers; wherein the plurality of truncated cone-shaped vertical cavity surface emitting lasers are arranged in a two-dimensional array on the substrate 1; the substrate 1 is arranged in the middle area of ​​the primary carrier plate 12, and the primary carrier plate 12 is connected to the plurality of truncated cone-shaped vertical cavity surface emitting lasers through a plurality of wires 13; the top of each truncated cone-shaped vertical cavity surface emitting laser is an upper contact layer 6, and the upper surface of the upper contact layer 6 is photolithographically formed into a strip grating 92, and at least one of the period, duty cycle, depth and relative rotation angle of the strip grating 92 on each truncated cone-shaped vertical cavity surface emitting laser is different from each other to form a two-dimensional laser dot matrix with different emission angles.

[0029] According to an embodiment of the present disclosure, the lidar scanning emission device provided by the present disclosure includes a plurality of frustum-shaped vertical cavity surface emitting lasers arranged in a two-dimensional array. The top of each frustum-shaped vertical cavity surface emitting laser is an upper contact layer 6, and strip gratings 92 with at least one of the period, duty cycle, depth, and relative rotation angle being different from each other are lithographically formed on the upper surface of the upper contact layer 6. In this way, the strip gratings 92 on the emission surfaces of the lasers cause interference and diffraction of the laser emitted by the lasers. The laser is strengthened in a certain direction or weakened in a certain direction, thereby forming two low-divergence angle lasers with an included angle of θ symmetric about the normal of the array plane, enabling the laser to be emitted at a specific angle. By adjusting at least one of the period, duty cycle, and depth of the strip gratings 92 on each frustum-shaped vertical cavity surface emitting laser, the emission angle θ of the laser is controlled to be between 0 degrees and 85 degrees, so that the laser emitted by each laser is emitted at a specific angle, which can be used to scan an object within a certain distance and determine the position through the reflection of the object. Each vertical cavity surface emitting laser only needs to be responsible for measuring a certain angle and does not require a complex optical path, increasing the utilization rate of the light source. Moreover, the scanning range of the laser generated by the lidar scanning emission device provided by the present disclosure can achieve a scanning range of 0 degrees to 170 degrees according to the size of its array scale. As Figure 1 shown, each frustum-shaped vertical cavity surface emitting laser is arranged in rows in the X-axis direction and in columns in the Y-axis direction. The relative rotation angle β (β is the included angle between the strip grating and the X-axis) of the frustum-shaped vertical cavity surface emitting lasers in each row is the same, and the grating periods are different. In the embodiment of the present disclosure, as Figure 1 shown, the relative rotation angle β of the strip grating 92 of the first row of frustum-shaped vertical cavity surface emitting lasers along the Y-axis direction is 0 degrees, the relative rotation angle β of the strip grating 92 of the second row of frustum-shaped vertical cavity surface emitting lasers is 30 degrees, the relative rotation angle β of the strip grating 92 of the third row of frustum-shaped vertical cavity surface emitting lasers is 60 degrees, the relative rotation angle β of the strip grating 92 of the fourth row of frustum-shaped vertical cavity surface emitting lasers is 90 degrees, and the relative rotation angle β of the strip grating 92 of the fifth row of frustum-shaped vertical cavity surface emitting lasers is 120 degrees. By adjusting the relative rotation angles of the strip gratings 92 on each frustum-shaped vertical cavity surface emitting laser, a two-dimensional laser dot matrix can be formed by a plurality of frustum-shaped vertical cavity surface emitting lasers. Compared with silicon-based phased array radars and Flash lidars, higher power output can be achieved. Compared with mechanical lidars, the present disclosure can achieve high power output while reducing the volume of the lidar and improving its integration, and can be more widely applied in autonomous driving, drones, robots, and other artificial intelligence fields.

[0030] In the embodiment of the present disclosure, the interval of the relative rotation angle β of the bar grating 92 is 30 degrees. In other embodiments, the interval of the relative rotation angle β of the bar grating 92 and the number of rows and columns can be selected by oneself, and the relative rotation angle β of the bar grating 92 ranges from 0 degrees to 180 degrees.

[0031] Those skilled in the art understand that a vertical-cavity surface-emitting laser (VCSEL for short, also known as a vertical resonant cavity surface-emitting laser) is a semiconductor laser whose laser emits perpendicular to the top surface.

[0032] According to an embodiment of the present disclosure, the material of the substrate 1 is N-type or P-type GaAs.

[0033] According to an embodiment of the present disclosure, the material of the upper contact layer 6 is AlGaAs or GaAs.

[0034] According to an embodiment of the present disclosure, the thickness range of the substrate 1 includes 80 - 200 microns, for example, it can be any one of 80 microns, 100 microns, 110 microns, 125 microns, 130 microns, 150 microns, 180 microns, 200 microns, etc.

[0035] In a schematic embodiment, the thickness of the substrate 1 is 145 microns.

[0036] In a schematic embodiment, the distribution periods of the bar gratings 92 on each frustum-shaped vertical-cavity surface-emitting laser are all different.

[0037] In a schematic embodiment, the duty cycles and depths of the bar gratings 92 on each vertical-cavity surface-emitting laser are all different.

[0038] In a schematic embodiment, the periods, duty cycles and depths of the bar gratings 92 on each vertical-cavity surface-emitting laser are all different.

[0039] According to an embodiment of the present disclosure, the length range of the bar grating 92 is less than the diameter of the frustum-shaped vertical-cavity surface-emitting laser.

[0040] According to an embodiment of the present disclosure, each frustum-shaped vertical-cavity surface-emitting laser includes: a lower Bragg reflector 2, disposed on the substrate 1 and forming a plurality of frustum-shaped structures; a transition layer 3, disposed on the lower Bragg reflector 2; an active layer 4, disposed on the transition layer 3 for generating laser; an upper Bragg reflector 5, disposed on the active layer 4, and the upper Bragg reflector 5 and the lower Bragg reflector 2 generate laser oscillation by reflecting the laser in the active layer 4.

[0041] In a schematic embodiment, the material of the lower Bragg reflector 2 is AlGaAs.

[0042] In a schematic embodiment, the material of the transition layer 3 is AlGaAs.

[0043] In a schematic embodiment, the material of the active layer 4 is InGaAs / GaAs quantum wells or quantum dots.

[0044] In a schematic embodiment, the material of the upper Bragg reflector 5 is AlGaAs.

[0045] According to an embodiment of the present disclosure, the refractive index of the upper Bragg reflector 5 is less than that of the lower Bragg reflector 2 so that a part of the light is emitted. The active layer 4 is sandwiched between the upper Bragg reflector 5 and the lower Bragg reflector 2. When the vertical cavity surface emitting laser operates, a standing wave is formed in the active region, so that the photon energy is amplified and finally lasing is formed. Limiting layers may also be included on both sides of the active layer 4. On the one hand, the limiting layers can play a role in limiting carriers, and on the other hand, they can adjust the length of the resonant cavity so that the resonant wavelength is exactly the laser wavelength of the required laser.

[0046] According to an embodiment of the present disclosure, each of the frustum-shaped vertical cavity surface emitting lasers is etched with a plurality of strip-shaped grooves 91 in the height direction. The depth of the strip-shaped grooves 91 (the distance between the top surface of the upper contact layer 6 and the bottom of the strip-shaped grooves 91) is less than the distance between the top surface of the upper contact layer 6 and the bottom surface of the upper Bragg reflector 5.

[0047] According to an embodiment of the present disclosure, a first carrier metal layer 121 and a second carrier metal layer 122 are provided on the primary carrier board 12. Among them, the first carrier metal layer 121 is provided at the four corners of the substrate 1; the second carrier metal layer 122 is provided at the bottom of the substrate 1 and in the middle of two adjacent first carrier metal layers 121; the first carrier metal layer 121 and the second carrier metal layer 122 are separated by a trench. The first carrier metal layer 121 and the second carrier metal layer 122 are separated by the trench to achieve electrical isolation between the first carrier metal layer 121 and the second carrier metal layer 122.

[0048] According to an embodiment of the present disclosure, the lidar scanning and emitting device further includes: an upper metal layer 7 and a lower metal layer 8. The upper metal layer 7 covers the side walls of the frustum-shaped vertical cavity surface emitting lasers and between two adjacent frustum-shaped vertical cavity surface emitting lasers, and the upper contact layer 7 is electrically connected to the upper contact layer 6; the lower metal layer 8 is provided between the substrate 1 and the second carrier metal layer 122 and is used to cooperate with the upper metal layer 7 to inject current into the frustum-shaped vertical cavity surface emitting lasers. When the upper metal layer 7 and the lower metal layer 8 provide the injection current, the active layer 4 provides gain to generate laser light.

[0049] According to an embodiment of the present disclosure, the primary carrier board 12 is used to carry a plurality of frustum-shaped vertical cavity surface emitting lasers. The interior of the primary carrier board 12 is provided with circuits for conducting signals between the lower metal layer 8, the upper metal layer 7, and the circuit board. In addition to the carrying function, the primary carrier board 12 also has additional functions such as protecting the circuit, the conducting wire 13, designing a heat dissipation path, and establishing a modular standard for components.

[0050] According to an embodiment of the present disclosure, the material of the lower metal layer 8 includes any one of gold germanium nickel gold alloy, indium, gold tin alloy, etc.

[0051] According to an embodiment of the present disclosure, a transparent insulating layer is provided on the surface of the strip-shaped groove 91, the side wall of the frustum-shaped vertical cavity surface emitting laser, and between two adjacent frustum-shaped vertical cavity surface emitting lasers. The upper metal layer 7 covers the transparent insulating layer. The transparent insulating layer has pores reserved on the upper contact layer 6. The upper metal layer 7 is connected to the upper contact layer 6 through the pores. The transparent insulating layer includes a first transparent insulating layer 10 and a second transparent insulating layer 11. Only the second transparent metal layer is covered on the side wall of the frustum-shaped vertical cavity surface emitting laser (for the specific process, see the detailed introduction of the preparation method of the present disclosure). The upper metal layer 7 includes: a first metal layer 71 and a second metal layer 72. The first metal layer 71 is set as an ohmic contact layer electrically connected to the upper contact layer 6. The second metal layer 72 covers the first metal layer 71, the side wall of the frustum-shaped vertical cavity surface emitting laser, and the second transparent insulating layer 11 between two adjacent frustum-shaped vertical cavity surface emitting lasers.

[0052] According to an embodiment of the present disclosure, the material of the second transparent insulating layer 11 is silicon dioxide or silicon nitride.

[0053] According to an embodiment of the present disclosure, the function of the first metal layer 71 is to form a good ohmic contact between the second metal layer 72 and the upper contact layer 6.

[0054] According to an embodiment of the present disclosure, the upper metal layer 7 is provided with a light exit port on the top surface of the frustum-shaped vertical cavity surface emitting laser to facilitate the emission of laser light.

[0055] According to an embodiment of the present disclosure, the lidar scanning emission device further includes: at least one electronic control switch, which is connected to the plurality of wires. The plurality of wires 13 electrically connect the first carrier board metal layer 121 to the upper metal layer 7, so that the electronic control switch controls the power supply of each frustum-shaped vertical cavity surface emitting laser. The electronic control switch controlled by the shift register and the circuit pins connected by the electronic control switch form a circuit board. The electronic control switch enables an external power supply to supply power to a plurality of frustum-shaped vertical cavity surface emitting lasers through the wires 13 respectively. The circuit board is connected to the external power supply to achieve scanning control drive. Specifically, each frustum-shaped vertical cavity surface emitting laser is connected to the primary carrier board through a wire, the primary carrier board is connected to the electronic control switch on the circuit board, and all the electronic control switches are connected to the output end of the laser current source module. During operation, the laser current source module is always in the on state, and the electrical switches connecting each frustum-shaped vertical cavity surface emitting laser are program-controlled by the shift register to turn on each frustum-shaped vertical cavity surface emitting laser.

[0056] In a schematic embodiment, the second metal layer 72 covers the side walls of each frustum-shaped vertical cavity surface emitting laser and between two adjacent frustum-shaped vertical cavity surface emitting lasers. The entire laser circuit is controlled by one electronic control switch to achieve simultaneous on / off of multiple frustum-shaped vertical cavity surface emitting lasers.

[0057] In a schematic embodiment, the second metal layer 72 is disconnected between two adjacent frustum-shaped vertical cavity surface emitting lasers to achieve electrical isolation. Each frustum-shaped vertical cavity surface emitting laser is respectively controlled by an electronic control switch, thereby achieving independent on / off of multiple frustum-shaped vertical cavity surface emitting lasers. In other embodiments, through the cooperation of the coverage of the second metal layer 72 between two adjacent frustum-shaped vertical cavity surface emitting lasers and the electronic control switch, the on / off of single, multiple, multiple rows, and multiple columns of frustum-shaped vertical cavity surface emitting lasers can be achieved.

[0058] According to an embodiment of the present disclosure, the material of the wire 13 includes: metal materials such as copper, iron, gold, silver, and alloys.

[0059] In a schematic embodiment, the wire 13 is a gold wire lead.

[0060] According to an embodiment of the present disclosure, the material of the primary carrier board 12 includes any one of aluminum nitride, sapphire, and a silicon wafer with a silicon dioxide layer grown on its surface, etc.

[0061] According to an embodiment of the present disclosure, the diameter of each frustum-shaped vertical cavity surface emitting laser is 10μm - 100μm, the height is 2μm - 10μm, and the period of the strip grating 92 is 1μm - 30μm.

[0062] In a schematic embodiment, each vertical cavity surface emitting laser may also be a square structure or other structures, and is arranged in a two-dimensional array on the substrate 1.

[0063] Another aspect of the present disclosure provides a method for manufacturing the above-mentioned lidar scanning emission device:

[0064] Referring to Figure 2a , grow a lower Bragg reflector 2, a transition layer 3, an active layer 4, an upper Bragg reflector 5 and an upper contact layer 6 on the substrate 1 as an epitaxial wafer.

[0065] Referring to Figure 2b , etch the epitaxial wafer to obtain a plurality of isolated frustum-shaped structures.

[0066] Referring to Figure 2c , etch a plurality of strip-shaped grooves 91 at uniform intervals along the height direction of each frustum-shaped structure to form a strip grating 92. Among them, at least one of the period, duty cycle, depth, and relative rotation angle of the strip gratings 92 on each frustum-shaped structure is different from each other.

[0067] Form an upper metal layer 7 at the top of each frustum-shaped structure, and the upper metal layer 7 forms a light outlet above the strip grating 92.

[0068] Form a lower metal layer 8 at the bottom of the substrate 1 to obtain a lidar scanning emission device composed of a plurality of frustum-shaped vertical cavity surface emitting lasers.

[0069] According to an embodiment of the present disclosure, the area where the top of the frustum-shaped vertical cavity surface emitting laser is not covered by the metal layer is the light outlet.

[0070] According to an embodiment of the present disclosure, the growth method of the epitaxial wafer includes growth by metalorganic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE).

[0071] According to an embodiment of the present disclosure, the step of forming the upper metal layer 7 on the top of each frustum-shaped structure and forming a light outlet on the upper metal layer 7 includes:

[0072] Form a first metal layer 71 on the top of each frustum-shaped structure, and form a first light outlet on the first metal layer 71;

[0073] Form a transparent insulating layer on the side wall of each frustum-shaped structure and between adjacent frustum-shaped structures;

[0074] Form a second metal layer 72 on the top of the first metal layer 71, on the side wall of the frustum-shaped structure, and on the transparent insulating layer between adjacent frustum-shaped structures, and form a second light outlet on the second metal layer 72 that cooperates with the first light outlet.

[0075] According to an embodiment of the present disclosure, the first light-emitting port is formed on the first metal layer 71 by any one or more of methods such as photolithography, etching, and stripping.

[0076] According to an embodiment of the present disclosure, the step of forming the second transparent insulating layer 11 on the sidewall of each frustum-shaped structure includes:

[0077] Referring to Figure 2e , a first transparent insulating layer 10 is covered on the sidewall of the frustum-shaped structure, on the first metal layer 71, and between two adjacent frustum-shaped structures.

[0078] Referring to Figure 2f , the first transparent insulating layer 10 on the sidewall of the frustum-shaped structure is removed.

[0079] An oxidation process is performed on the frustum-shaped structure.

[0080] Referring to Figure 2g , the second transparent insulating layer 11 is covered again on the sidewall of the frustum-shaped structure, on the first metal layer 71, and between two adjacent frustum-shaped structures.

[0081] Referring to Figure 2h , the first transparent insulating layer 10 and the second transparent insulating layer 11 above the first metal layer 71 are removed.

[0082] According to an embodiment of the present disclosure, the first transparent insulating layer 10 is used to prevent the strip grooves 91 and the strip grating 92 structure from being oxidized during the oxidation process.

[0083] According to an embodiment of the present disclosure, the material of the first transparent insulating layer 10 is silicon dioxide or silicon nitride.

[0084] According to an embodiment of the present disclosure, performing an oxidation process on the polar structure is to limit the injection current of the frustum-shaped vertical cavity surface emitting laser and reduce the lasing current.

[0085] In a schematic embodiment, a preparation method of the above-mentioned lidar scanning emission device is as follows:

[0086] As Figure 2a shown, a lower Bragg reflector 2, a transition layer 3, an active region, an upper Bragg reflector 5, and an upper contact layer 6 are formed on a substrate 1 as an epitaxial wafer.

[0087] The epitaxial wafer is dry-etched to the lower Bragg reflector 2 to form a plurality of frustum-shaped structures on the lower Bragg reflector 2. As Figure 2b shown, a plurality of mutually isolated frustum-shaped structures are obtained. A plurality of strip grooves 91 are etched downward at uniform intervals along the height direction of each frustum-shaped structure to form a strip grating 92. Among them, the depths of the strip grooves 91 on each frustum-shaped structure are different. As Figure 2cAs shown, from left to right along the X-axis direction are the first to fourth frustum-shaped structures. Among them, the depth of the strip groove of the third frustum-shaped structure > the depth of the strip groove of the fourth frustum-shaped structure > the depth of the strip groove of the second frustum-shaped structure > the depth of the strip groove of the first frustum-shaped structure.

[0088] As Figure 2d shown, a first metal layer 71 is formed at the top of each frustum-shaped structure, and a first light-emitting port is formed on the first metal layer 71.

[0089] As Figure 2e shown, a first transparent insulating layer 10 is covered on the side walls of the frustum-shaped structures, on the first metal layer 71, and between two adjacent frustum-shaped structures.

[0090] As Figure 2f shown, the first transparent insulating layer 10 on the side walls of the frustum-shaped structures is removed, and an oxidation process is performed on the frustum-shaped structures.

[0091] As Figure 2g shown, a second transparent insulating layer 11 is covered again on the side walls of the frustum-shaped structures, on the first metal layer 71, and between two adjacent frustum-shaped structures.

[0092] As Figure 2h shown, the first transparent insulating layer 10 and the second transparent insulating layer 11 above the first metal layer 71 are removed.

[0093] As Figure 2i shown, a second metal layer 72 is formed on the top of the first metal layer 71 and on the transparent insulating layer on the side walls of the frustum-shaped structures, and a second light-emitting port that cooperates with the first light-emitting port is formed on the second metal layer 72.

[0094] To facilitate subsequent cleavage and heat conduction of each frustum-shaped surface-emitting laser, the substrate 1 is thinned so that the thickness of the substrate 1 is 135 microns. As Figure 2j shown, a lower metal layer 8 is formed at the bottom of the thinned substrate 1, and a plurality of frustum-shaped vertical cavity surface-emitting laser structures arranged in a two-dimensional array are formed.

[0095] The plurality of frustum-shaped vertical cavity surface-emitting laser structures arranged in a two-dimensional array are alloyed under a mixed gas of nitrogen and hydrogen at a high temperature (400 °C - 420 °C), and then cleaved to obtain an array chip.

[0096] The array chip is fixed on a primary carrier board 12 using a thermal conductive adhesive, and the upper metal layer 7 is connected to the first carrier board metal layer 121 using a wire 13.

[0097] The first carrier board metal layer 121 is connected to a circuit board to complete the preparation of the final lidar emission device.

[0098] In another illustrative embodiment, a method for fabricating a lidar scanning emission device is as follows:

[0099] Form a lower Bragg reflector 2, a transition layer 3, an active region, an upper Bragg reflector 5, and an upper contact layer 6 on a substrate 1 to form an epitaxial wafer.

[0100] Grow a first metal layer 71 at the top of the epitaxial wafer and reserve a light-emitting window.

[0101] Etch a strip-shaped groove 91 at the top of the frustum-shaped structure within the reserved light-emitting window. The periods and depths of the strip-shaped gratings 92 in different light-emitting windows are different.

[0102] Grow a first transparent insulating layer 10 at the top of the frustum-shaped laser. The material of the first transparent insulating layer 10 is silicon nitride.

[0103] Dry-etch down to the lower Bragg reflector 2 to obtain a plurality of frustum-shaped structures.

[0104] Perform an oxidation process on the frustum-shaped structures to reduce the lasing current of the laser.

[0105] Cover the second transparent insulating layer 11 again. The material of the second transparent insulating layer 11 is silicon nitride.

[0106] Remove the first transparent insulating layer 10 and the second transparent insulating layer 11 above the first metal layer 71, and cover the second metal layer 72 on the transparent insulating layer so that the second metal layer 72 contacts the first metal layer 71 to form an upper metal layer 7.

[0107] Reduce the thickness of the substrate 1 to a range of 100 microns to 150 microns, and grow a lower metal layer 8 at the bottom of the substrate 1 to form a plurality of frustum-shaped vertical cavity surface emitting laser structures arranged in a two-dimensional array.

[0108] Apply high temperature (400 °C - 420 °C) to the plurality of frustum-shaped vertical cavity surface emitting laser structures arranged in a two-dimensional array in a mixed gas of nitrogen and hydrogen for alloying, and then divide the obtained laser chip into array device die, that is, perform cleavage, to obtain an array chip.

[0109] Those skilled in the art can understand that the features recited in the various embodiments and / or claims of the present disclosure can be combined or combined in various ways, even if such combinations or combinations are not explicitly recited in the present disclosure. In particular, without departing from the spirit and teachings of the present disclosure, the features recited in the various embodiments and / or claims of the present disclosure can be combined and combined in various ways. All such combinations and / or combinations fall within the scope of the present disclosure.

[0110] Although the present disclosure has been shown and described with reference to specific exemplary embodiments thereof, those skilled in the art should understand that various changes in form and detail may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. Accordingly, the scope of the present disclosure should not be limited to the above-described embodiments, but should be determined not only by the appended claims but also by the equivalents of the appended claims.

Claims

1. A lidar scanning emission device, characterized in that, it includes: a substrate (1); a plurality of frustum-shaped vertical cavity surface emitting lasers, arranged in a two-dimensional array on the substrate (1); a primary carrier board (12), the substrate (1) is arranged in the middle area of the primary carrier board (12), and the primary carrier board (12) is connected to the plurality of frustum-shaped vertical cavity surface emitting lasers through a plurality of wires (13); wherein, the top of each frustum-shaped vertical cavity surface emitting laser is an upper contact layer (6), and a strip grating (92) is formed by photolithography on the upper surface of the upper contact layer (6). At least one of the period, duty cycle, depth, and relative rotation angle of the strip gratings (92) on each frustum-shaped vertical cavity surface emitting laser is different from each other to form a two-dimensional laser dot array with different emission angles.

2. The lidar scanning emission device according to claim 1, characterized in that, each frustum-shaped vertical cavity surface emitting laser includes: a lower Bragg reflector (2), arranged on the substrate (1); a transition layer (3), arranged on the lower Bragg reflector (2); an active layer (4), arranged on the transition layer (3) and used for generating laser; an upper Bragg reflector (5), arranged on the active layer (4), and the upper Bragg reflector (5) and the lower Bragg reflector (2) generate laser oscillation by reflecting the laser in the active layer (4).

3. The lidar scanning emission device according to claim 1, characterized in that, each frustum-shaped vertical cavity surface emitting laser is etched with a plurality of strip grooves (91) along the height direction.

4. The lidar scanning emission device according to claim 1, characterized in that, a first carrier board metal layer (121) and a second carrier board metal layer (122) are arranged on the primary carrier board (12), wherein, the first carrier board metal layer (121) is arranged at the four corners of the substrate (1); the second carrier board metal layer (122) is arranged at the bottom of the substrate (1) and in the middle of two adjacent first carrier board metal layers (121); the first carrier board metal layer (121) and the second carrier board metal layer (122) are separated by a trench.

5. The lidar scanning emission device according to claim 4, characterized in that, it further includes: an upper metal layer (7), covering the side walls of the frustum-shaped vertical cavity surface emitting lasers and between two adjacent frustum-shaped emitting lasers. The upper metal layer (7) is electrically connected to the upper contact layer (6), and the upper metal layer (7) is electrically connected to the first carrier board metal layer (121) through the wire (13); a lower metal layer (8), arranged between the substrate (1) and the second carrier board metal layer (122), and used to cooperate with the upper metal layer (7) to inject current into the frustum-shaped vertical cavity surface emitting lasers.

6. The lidar scanning emission device according to claim 5, characterized in that, A transparent insulating layer is provided on the surface of the strip-shaped groove (91), on the side wall of the frustum-shaped vertical cavity surface emitting laser, and between two adjacent frustum-shaped vertical cavity surface emitting lasers. The upper metal layer (7) covers the transparent insulating layer. The transparent insulating layer has pores reserved on the upper contact layer (6). The upper metal layer (7) is connected to the upper contact layer (6) through the pores.

7. A lidar scanning emission device according to claim 5, wherein, the upper metal layer (7) is provided with a light outlet on the top surface of the frustum-shaped vertical cavity surface emitting laser.

8. A lidar scanning emission device according to claim 1, wherein, the lidar scanning emission device further includes: at least one electronic control switch, which is connected to the plurality of wires (13) and is used to control the power supply of each frustum-shaped vertical cavity surface emitting laser.

9. A lidar scanning emission device according to claim 1, wherein, the diameter of each frustum-shaped vertical cavity surface emitting laser is 10 μm to 100 μm, the height is 2 μm to 10 vm, and the period of the strip-shaped grating (92) is 1 μm to 30 μm.

10. A preparation method of a lidar scanning emission device applied to any one of claims 1-9, wherein, it includes: growing a substrate (1) on a primary carrier plate (12); growing and etching a frustum-shaped epitaxial wafer on the substrate (1) to obtain a plurality of frustum-shaped structures arranged in a two-dimensional array; etching a plurality of strip-shaped grooves (91) at uniform intervals along the height direction of each frustum-shaped structure to form a strip-shaped grating (92), and at least one of the period, duty cycle, depth, and relative rotation angle of the strip-shaped grating (92) on each frustum-shaped structure is different from each other.

Images