A lidar system based on multi-wavelength VCSEL lasers

Abstract

This invention discloses a lidar system based on a multi-wavelength VCSEL laser, belonging to the field of lidar technology. It includes a signal transmitting module, a rotating mirror module, a signal receiving module, and a data processing module. The signal transmitting module comprises a multi-wavelength VCSEL laser, which includes a substrate and n VCSEL units stacked on the substrate surface. Each VCSEL unit has a wavelength range of 600-1800 nm, with the wavelength of the lower-layer VCSEL unit being greater than that of the upper-layer VCSEL unit. An N-type metal electrode is provided at the bottom of the substrate, and a P-type metal electrode is provided on top of the uppermost VCSEL unit. This invention integrates multiple VCSEL units of different wavelengths into a single VCSEL chip, resulting in advantages such as small footprint, low packaging cost, high production efficiency, high product yield, and high product reliability. This provides necessary technical support for lidar to achieve in-depth detection for physical property identification.

Description

Technical Field

[0001] This invention relates to the field of lidar technology, and in particular to a lidar system based on a multi-wavelength VCSEL laser. Background Technology

[0002] LiDAR (Light Detection and Ranging) is a radar system that detects the position, velocity, and other characteristics of targets by emitting laser beams. It is an advanced detection method that combines laser technology with photoelectric detection technology. Due to its high resolution, good concealment, strong resistance to active interference, good low-altitude detection performance, small size, and light weight, LiDAR is widely used in fields such as autonomous driving, drones, intelligent robots, transportation and communication, energy security monitoring, and resource exploration.

[0003] Depending on the detection requirements, existing lidar systems typically include single-wavelength lidar and multi-wavelength lidar. Traditional multi-wavelength lidar uses a single-wavelength laser and a wavelength converter to transform the laser beam from the single-wavelength laser into a multi-wavelength laser beam from the target. This method increases system cost, complexity, failure rate, and maintenance difficulty. Therefore, existing multi-wavelength lidar typically integrates multiple lasers of different wavelengths together through packaging (surface mount, wire bonding) to form a laser emitting unit with multiple wavelengths. However, this integration method through packaging occupies a large space, has high packaging costs, introduces significant yield losses during the packaging process, and introduces too many potential surface mount and wire bonding defects, affecting overall reliability.

[0004] In addition, although existing lidar systems have outstanding advantages in acquiring three-dimensional spatial information, their ability to detect environmental information such as the classification of physical properties and states still needs to be improved due to the limitation of lidar's single-wavelength detection capability. Summary of the Invention

[0005] This invention provides a lidar system based on a multi-wavelength VCSEL laser, the main purpose of which is to solve the problems existing in the prior art.

[0006] The present invention adopts the following technical solution:

[0007] A lidar system based on a multi-wavelength VCSEL laser includes a signal transmitting module, a rotating mirror module, a signal receiving module, and a data processing module. The signal transmitting module includes a multi-wavelength VCSEL laser, which comprises a substrate and n VCSEL units stacked on the substrate surface, where n ≥ 2. The wavelength range of each VCSEL unit is 600-1800 nm, and the wavelength of the lower-layer VCSEL unit is greater than that of the upper-layer VCSEL unit. An N-type metal electrode is provided at the bottom of the substrate, and a P-type metal electrode is provided on top of the uppermost VCSEL unit.

[0008] Furthermore, each VCSEL unit comprises, from bottom to top, an N-type DBR, an active region, an oxide confinement layer, and a P-type DBR, and a tunneling junction layer is provided between two adjacent VCSEL units.

[0009] Furthermore, the N-type DBR and P-type DBR of each VCSEL unit are periodic structures composed of alternating high-refractive-index thin films and low-refractive-index thin films; the number of periods of P-type DBR in the same VCSEL unit is less than the number of periods of N-type DBR; the number of periods of P-type DBR in the upper VCSEL unit is less than the number of periods of P-type DBR in the lower VCSEL unit.

[0010] Furthermore, each VCSEL unit comprises, from bottom to top, a bottom N-type DBR, an active region, a buried tunnel junction, and a top N-type DBR, and the diameter of the buried tunnel junction of each VCSEL unit is equal, ranging from 5 to 150 μm.

[0011] Furthermore, both the bottom N-type DBR and the top N-type DBR are periodic structures composed of alternating high-refractive-index thin films and low-refractive-index thin films; the number of cycles of the top N-type DBR in the same VCSEL cell is less than the number of cycles of the bottom N-type DBR; the number of cycles of the top N-type DBR in the upper VCSEL cell is less than the number of cycles of the top N-type DBR in the lower VCSEL cell.

[0012] Furthermore, the number of VCSEL units is four, and the wavelength ranges of the four VCSEL units stacked from bottom to top are 1285-1405nm, 1025-1095nm, 880-950nm and 780-850nm, respectively.

[0013] Furthermore, the detection method of the lidar system includes the following steps:

[0014] S1. Obtain the spectral reflectance characteristic curves of different detection targets in the application scenario of the lidar system within a set wavelength range through preliminary experiments, and construct a reflectance spectrum library accordingly.

[0015] S2. Based on the reflection spectrum library, with the aim of identifying the physical properties of different detection targets, select n typical wavelengths as the target wavelengths of the multi-wavelength VCSEL laser, and fabricate the multi-wavelength VCSEL laser.

[0016] S3. Control the multi-wavelength VCSEL laser to simultaneously emit detection laser beams with n different target wavelengths by driving signals;

[0017] S4. The detection laser beam is emitted after being reflected by the rotating mirror module;

[0018] S5. The emitted detection laser beam is reflected off the detection target to form a return beam, which then returns to the rotating mirror module.

[0019] S6. The signal receiving module receives the reflected light beam from the rotating mirror module and converts it into an electrical signal.

[0020] S7. The data processing module performs reflectance spectrum matching on the electrical signals received by the signal receiving module based on the reflectance spectrum library, thereby realizing the identification of the physical properties of the target and achieving the purpose of environmental perception.

[0021] Furthermore, step S1 includes the following sub-steps:

[0022] S11. Select typical targets in the application scenario of the lidar system as detection targets;

[0023] S12. Classify the same detection target according to its physical properties based on color, material, and type;

[0024] S13. Obtain the spectral reflectance characteristic curves of the same detection target with different physical properties within a set wavelength range through detection experiments, and store them in the reflectance spectrum library.

[0025] Furthermore, the signal transmission module includes a multi-wavelength VCSEL laser, a collimating optical element, and a diffractive optical element arranged sequentially along the optical path direction. The probe laser beam emitted by the multi-wavelength VCSEL laser is processed by the collimating optical element and the diffractive optical element before being emitted.

[0026] Furthermore, the signal receiving device includes a filter, a focusing lens, and m detectors arranged along the optical path direction, where m ≥ n; the reflected light beam from the target is processed by the filter and the focusing lens and then received by the detector of the corresponding wavelength.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. This invention integrates multiple VCSEL units of different wavelengths into a single VCSEL chip. Compared with the existing technology that uses multiple independently set VCSEL chips, the on-chip integrated multi-wavelength VCSEL laser has the advantages of small footprint, low packaging cost, high production efficiency, high product yield and high product reliability, providing necessary technical support for lidar to achieve in-depth detection of physical properties.

[0029] 2. The detection method provided by this invention enables lidar technology to retain high-resolution spatial detection capabilities while recognizing and perceiving the properties of objects in the environment, further expanding the application scenarios of lidar and enriching its detection functions. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the multi-wavelength VCSEL laser in Embodiment 1 of the present invention.

[0031] Figure 2 This is a schematic diagram of the lidar system in Embodiments 1 and 2 of the present invention.

[0032] Figure 3 This is a graph showing the spectral reflectance characteristics of different plant species in this invention.

[0033] Figure 4 This is a schematic diagram of the structure of the multi-wavelength VCSEL laser in Embodiment 2 of the present invention.

[0034] In the picture:

[0035] 10. Substrate;

[0036] 11. First VCSEL unit;

[0037] 111. First N-type DBR;

[0038] 112. First active region;

[0039] 113. First oxidation confinement layer;

[0040] 114. First P-type DBR;

[0041] 12. Second VCSEL unit;

[0042] 121. Second type N DBR;

[0043] 122. Second active region;

[0044] 123. Second oxidation confinement layer;

[0045] 124. Second type P DBR;

[0046] 13. Third VCSEL unit;

[0047] 131. Type N DBR;

[0048] 132. The third active region;

[0049] 133. Third oxidation confinement layer;

[0050] 134. Third P-type DBR;

[0051] 14. Fourth VCSEL unit;

[0052] 141. Fourth type N DBR;

[0053] 142. The fourth active region;

[0054] 143. Fourth Oxidation Confinement Layer;

[0055] 144. Fourth type P-type DBR;

[0056] 15. First tunnel-crossing layer;

[0057] 16. Second tunnel-crossing layer;

[0058] 17. The third tunnel-crossing layer;

[0059] 18. N-type metal electrode;

[0060] 19. P-type metal electrode.

[0061] 20. Substrate;

[0062] 21. First VCSEL unit;

[0063] 211. First bottom N-type DBR;

[0064] 212. First active region;

[0065] 213. First buried tunnel connection;

[0066] 214. First top N-type DBR;

[0067] 22. Second VCSEL unit;

[0068] 221. Second bottom N-type DBR;

[0069] 222. Second active region;

[0070] 223. Second buried tunnel connection;

[0071] 224. Second top N-type DBR;

[0072] 23. Third VCSEL unit;

[0073] 231. Third bottom N-type DBR;

[0074] 232. The third active region;

[0075] 233. The third buried tunnel is connected;

[0076] 234. Third top N-type DBR;

[0077] 24. Fourth VCSEL unit;

[0078] 241. Fourth bottom N-type DBR;

[0079] 242. The fourth active region;

[0080] 243. Fourth buried tunnel connection;

[0081] 244. Fourth top N-type DBR;

[0082] 25. First N-type metal electrode;

[0083] 26. Second N-type metal electrode. Detailed Implementation

[0084] Specific embodiments of the present invention will now be described with reference to the accompanying drawings. Many details are described below to provide a comprehensive understanding of the invention; however, those skilled in the art will be able to implement the invention without these details.

[0085] Example 1:

[0086] like Figure 1 and Figure 2 As shown, this invention provides a lidar system based on a multi-wavelength VCSEL laser. To more clearly explain the working principle of this lidar system, the multi-wavelength VCSEL laser will be described in detail below:

[0087] like Figure 1As shown, the multi-wavelength VCSEL laser includes a substrate 10 and n VCSEL units stacked on the substrate surface, where n ≥ 2. Each VCSEL unit has a wavelength range of 600-1800 nm, and the wavelength of the lower-layer VCSEL unit is greater than that of the upper-layer VCSEL unit. Preferably, in this embodiment, the number of VCSEL units is four (i.e., n = 4), including a first VCSEL unit 11, a second VCSEL unit 12, a third VCSEL unit 13, and a fourth VCSEL unit 14 stacked from bottom to top. The main inventive concept of this invention lies in stacking and integrating four different wavelength VCSEL units required for lidar detection into a single VCSEL chip. This allows the VCSEL chip to emit four detection laser beams required for lidar detection. Since the band gap of the material corresponding to the long-wavelength VCSEL unit is smaller than that of the material corresponding to the short-wavelength VCSEL unit, the long-wavelength VCSEL unit structure will absorb the laser light from the short-wavelength VCSEL unit to a certain extent. Based on this, the design principle of this invention is that the wavelength of the VCSEL unit located in the next layer must be greater than the wavelength of the VCSEL unit located in the previous layer, in order to avoid the absorption of the laser light from the short-wavelength VCSEL unit by the long-wavelength VCSEL unit structure along the laser emission direction.

[0088] like Figure 1 As shown, a first N-type metal electrode 18 is provided at the bottom of the substrate 10, and a second N-type metal electrode 19 is provided at the top of the fourth VCSEL unit 14. In this way, the four VCSEL units can be controlled simultaneously by the driving signal to emit detection laser beams of different wavelengths to meet the detection requirements of the lidar.

[0089] like Figure 1As shown, the first VCSEL unit 11 includes, from bottom to top, a first N-type DBR 111, a first active region 112, a first oxide confinement layer 113, and a first P-type DBR 114; the second VCSEL unit 12 includes, from bottom to top, a second N-type DBR 121, a second active region 122, a second oxide confinement layer 123, and a second P-type DBR 124; the third VCSEL unit 13 includes, from bottom to top, a third N-type DBR 131, a third active region 132, a third oxide confinement layer 133, and a third P-type DBR 114. DBR134; The fourth VCSEL unit 14, from bottom to top, includes a fourth N-type DBR141, a fourth active region 142, a fourth oxide confinement layer 143, and a fourth P-type DBR144; A first tunneling junction layer 15 is provided between the first VCSEL unit 11 and the second VCSEL unit 12; A second tunneling junction layer 16 is provided between the second VCSEL unit 12 and the third VCSEL unit 13; A third tunneling junction layer 17 is provided between the third VCSEL unit 13 and the fourth VCSEL unit 14. The tunneling junction layer between adjacent VCSEL units enables the series connection and current conduction of multiple quantum wells in each active region, thereby generating high gain and reducing the total capacitance, which is beneficial for high-speed modulation of multi-wavelength VCSEL lasers.

[0090] like Figure 1 As shown, in this embodiment, all tunneling junctions have the same structure, consisting of a P-type heavily doped layer and an N-type heavily doped layer from bottom to top. The materials for the P-type heavily doped layer include, but are not limited to, InGaAsP, InGaAlAs, AlInAs, GaAs, AlGaAs, and GaAsSb; the materials for the N-type heavily doped layer include, but are not limited to, AlGaAs, GaAs, GaInAs, and InP. The doping atoms for the P-type heavily doped layer include C, Mg, Zn, or Be; the doping atoms for the N-type heavily doped layer include Se or Te. The doping concentration of the P-type and N-type heavily doped layers is 10. 19 -10 20 cm -3 Order of magnitude; the thickness of P-type heavily doped layers ranges from 8 to 50 nm, and the thickness of N-type heavily doped layers ranges from 8 to 50 nm.

[0091] like Figure 1 As shown, the first N-type DBR111, the first P-type DBR114, the second N-type DBR121, the second P-type DBR124, the third N-type DBR131, the third P-type DBR134, the fourth N-type DBR141, and the fourth P-type DBR144 are all periodic structures composed of alternating high-refractive-index thin films and low-refractive-index thin films, and the number of periods gradually decreases from bottom to top, thereby ensuring that the laser emits light upwards.

[0092] like Figure 1As shown, substrate 10 is a GaAs substrate. Based on this, the N-type DBR and P-type DBR of each VCSEL unit can be made of AlGaAs / GaAs, AlAs / GaAs, InGaAlAs / InP, InGaAsP / InP, or AlGaInAs / AlInAs semiconductor materials. The active layer of each VCSEL unit can be designed as multiple overlapping quantum well layers (MQWs), and the quantum well layers are composed of GaAs, AlGaAs, GaAsP and InGaAs materials stacked together.

[0093] like Figure 1 As shown, this invention innovatively integrates four VCSEL units of different wavelengths into a single VCSEL chip. Compared to the existing technology that uses four independently configured VCSEL chips, this invention has advantages such as smaller footprint, lower packaging cost, higher production efficiency, higher product yield, and higher product reliability, as specifically demonstrated below:

[0094] (1) Stacking and integrating four different wavelength VCSEL units into the same VCSEL chip can effectively reduce the space occupied, greatly save the chip packaging area, and facilitate the miniaturization design requirements of lidar.

[0095] (2) The on-chip integrated multi-wavelength VCSEL laser saves on the total chip manufacturing process cost, testing cost and packaging cost, and also eliminates the need for the coupler required by the four independent VCSEL chips in existing lidar. In addition, the on-chip integrated multi-wavelength VCSEL laser has a low failure rate, thus saving on maintenance and replacement costs.

[0096] (3) The multi-wavelength VCSEL laser integrated on the chip can complete the manufacturing of multiple chips in one fabrication process. It does not require multiple chip processes to produce each different wavelength VCSEL chip separately, which can greatly reduce the total chip manufacturing process and time, and multiply the production efficiency.

[0097] (4) Generally speaking, the production yield of a single VCSEL chip is only over 90%, and the cumulative production yield of 4 VCSEL chips is even lower. Therefore, on-chip integrated multi-wavelength VCSEL lasers can greatly reduce the overall production defect rate and improve the overall product yield.

[0098] (5) The failure rate of the on-chip integrated multi-wavelength VCSEL laser is several orders of magnitude lower than that of the multi-chip package level, and it can greatly reduce the potential defects and early failures introduced by the package and wire bonding, which is in line with the simplified design principle of reliability design.

[0099] like Figure 2 As shown, the structure of the lidar system will be described in detail below:

[0100] A lidar system includes a signal transmitting module, a rotating mirror module, a signal receiving module, and a data processing module. Among them:

[0101] The signal transmission module includes a multi-wavelength VCSEL laser, a collimating optical element, and a diffractive optical element arranged sequentially along the optical path. The probe laser beam emitted by the multi-wavelength VCSEL laser is processed by the collimating optical element and the diffractive optical element before being emitted.

[0102] The rotating mirror module is used to emit the detection laser beam in different directions and angles, and simultaneously reflect back the light beam from targets at multiple different directions and angles to the signal receiving module. In this embodiment, the rotating mirror module is preferably a multi-faceted rotating mirror with multiple reflective surfaces.

[0103] The signal receiving device includes an aperture / filter, a focusing lens, and m detectors arranged along the optical path, where m ≥ n. Specifically, setting an aperture or filter at the receiving focal plane can filter out stray light, thereby allowing only the reflected backlight beam within the corresponding wavelength range to pass through, thus reducing noise and improving the signal-to-noise ratio; the focusing lens can focus the received backlight beam so that the corresponding detector can receive the backlight beam. Each detector is used to convert the received echo beam signal of the corresponding wavelength emitted by the corresponding laser and reflected by the target object into an electrical signal.

[0104] like Figure 2 and Figure 3 As shown, the detection method of this lidar system is described below, which includes the following steps:

[0105] S1. Obtain the spectral reflectance characteristic curves of different detection targets within a set wavelength range in the application scenario of the lidar system through preliminary experiments, thereby constructing a reflectance spectrum library. Specifically, this includes the following sub-steps:

[0106] S11. Select typical targets in the application scenarios of the lidar system as detection targets; taking the application scenario of intelligent driving as an example, typical targets generally include humans, plants, roads, buildings and vehicles.

[0107] S12. Classify the same detection target according to its physical properties, such as color, material, and type. For example, classify vehicles in the application scenario into different colors such as white, black, and blue; classify roads in the application scenario into different materials such as asphalt roads, dirt roads, and weed roads; and classify plants in the application scenario into different types such as camphor trees, magnolias, and photinia.

[0108] S13. Obtain the spectral reflectance characteristic curves of the same detection target with different physical properties within a set wavelength range through detection experiments, and store them in the reflectance spectrum library. Figure 3This figure shows the spectral reflectance characteristics of different plant species within the detection wavelength range, obtained through detection experiments. According to the figure, all plant species exhibit a reflectance peak around 550 nm in the visible light spectrum, an absorption peak near 680 nm, and a pronounced red-edge effect between 680-740 nm, with a rapid increase in reflectance for each species. In the near-infrared region, the reflectance of plants used as greenbelts along roadsides and in the median strips is generally between 35% and 60%.

[0109] S2. Based on a reflectance spectrum library, and with the aim of identifying the physical properties of different detection targets, typical wavelengths from n are selected as the target wavelengths for a multi-wavelength VCSEL laser, and this multi-wavelength VCSEL laser is fabricated. Taking plant species identification as an example, from... Figure 3 It can be clearly seen that the sensitive wavelength range of the lidar is 780-850 nm. Within this band, different types of plants exhibit significant differences in reflectivity. The principle for selecting the target wavelength is to achieve the identification of the physical properties of different targets with the fewest possible wavelengths. After numerous repeated experiments, it was found that in the application scenario of intelligent driving, the sensitive wavelengths of the lidar are 1285-1405 nm, 1025-1095 nm, 880-950 nm, and 780-850 nm. These four bands cover the wavelengths required for the identification of the physical properties of typical targets such as humans, plants, roads, buildings, and vehicles. Therefore, in this embodiment, the number of VCSEL units in the multi-wavelength VCSEL laser is set to four, and the wavelengths of the four VCSEL units stacked from bottom to top are preferably 1310 nm, 1064 nm, 905 nm, and 808 nm, respectively.

[0110] S3. The multi-wavelength VCSEL laser is controlled by the driving signal to simultaneously emit probe laser beams with four different target wavelengths. The probe laser beams are processed by collimating optical elements and diffractive optical elements before being emitted.

[0111] S4. The detection laser beam is emitted after being reflected from the upper or lower part of one of the reflecting surfaces of the multi-faceted rotating mirror.

[0112] S5. The emitted detection laser beam is reflected on the detection target to form a return beam. The return beam is reflected by the lower or upper part of one of the reflecting surfaces of the multi-faceted rotating mirror and then received by the signal receiving module.

[0113] S6. The reflected light beam is processed by a filter and a focusing lens and then received by a detector of the corresponding wavelength, and converted into an electrical signal.

[0114] S7. The data processing module, based on the reflectance spectrum library, performs reflectance spectrum matching on the electrical signals received by the signal receiving module, thereby realizing the identification of the physical properties of the detected target and achieving the purpose of environmental perception.

[0115] Compared with existing technologies, the lidar system of this invention has the following advantages:

[0116] (1) This invention enables lidar technology to retain high-resolution spatial detection capabilities while recognizing and perceiving the properties of objects in the environment, further expanding the application scenarios of lidar and enriching its detection functions.

[0117] (2) In this invention, each detector receives only a laser beam that matches the wavelength of the corresponding laser, thereby filtering out stray light and avoiding crosstalk between detectors that are activated at the same time. It can also reduce the interference noise caused by ambient light (such as sunlight, street light, etc., whose wavelengths are usually different from the wavelength of the laser beam), effectively ensuring the accuracy and performance of the laser radar signal reception.

[0118] Example 2:

[0119] like Figure 4 As shown, unlike Embodiment 1, the epitaxial structure of each VCSEL unit in this embodiment uses buried tunneling instead of an oxide confinement layer. Specifically, the first VCSEL 21 unit includes, from bottom to top, a first bottom N-type DBR 211, a first active region 212, a first buried tunneling junction 213, and a first top N-type DBR 214; the second VCSEL 22 unit includes, from bottom to top, a second bottom N-type DBR 221, a second active region 222, a third buried tunneling junction 223, and a second top N-type DBR 224; the third VCSEL 23 unit includes, from bottom to top, a third bottom N-type DBR 231, a third active region 232, a third buried tunneling junction 233, and a third top N-type DBR 234; and the fourth VCSEL 24 unit includes, from bottom to top, a fourth bottom N-type DBR 241, a fourth active region 242, a fourth buried tunneling junction 243, and a fourth top N-type DBR 244. The diameters of the first buried tunnel penetration joint 213 to the fourth buried tunnel penetration joint 243 are all equal, with a range of 5-150μm.

[0120] like Figure 1 As shown, the buried tunneling junction in this invention has the following functions: First, it achieves current limiting by burying the tunneling junction, thereby overcoming the problems of low production yield and poor product consistency that exist in the existing oxidation limiting method; Second, it reverses the polarity of the top N-type DBR in each VCSEL unit by using the buried tunneling junction, making it able to replace the top P-type DBR, thereby greatly reducing optical loss and series resistance, helping to improve conversion efficiency and achieve high-speed operation; Third, after replacing the top P-type DBR with the top N-type DBR, it can also overcome the epitaxial non-uniformity introduced by the top P-type DBR due to the need for high C doping, effectively improving epitaxial uniformity and yield.

[0121] The above are merely specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using the design concept shall be considered an infringement of the protection scope of the present invention.

Claims

1. A lidar system based on a multi-wavelength VCSEL laser, comprising a signal transmitting module, a rotating mirror module, a signal receiving module, and a data processing module, characterized in that: The signal transmitting module includes a multi-wavelength VCSEL laser, which includes a substrate and n VCSEL units stacked on the surface of the substrate, where n≥2; the wavelength range of each VCSEL unit is 600-1800nm, and the wavelength of the VCSEL unit located in the lower layer is greater than the wavelength of the VCSEL unit located in the upper layer; an N-type metal electrode is provided at the bottom of the substrate, and a P-type metal electrode is provided at the top of the uppermost VCSEL unit; The signal receiving device includes a filter, a focusing lens, and m detectors arranged along the optical path, where m ≥ n; the reflected light beam from the target is processed by the filter and the focusing lens and then received by the detectors of the corresponding wavelength. The detection method of the lidar system includes the following steps: S1. Obtain the spectral reflectance characteristic curves of different detection targets in the application scenario of the lidar system within a set wavelength range through preliminary experiments, and construct a reflectance spectrum library accordingly. S2. Based on the reflection spectrum library, with the aim of identifying the physical properties of different detection targets, select n typical wavelengths as the target wavelengths of the multi-wavelength VCSEL laser, and fabricate the multi-wavelength VCSEL laser. S3. Control the multi-wavelength VCSEL laser to simultaneously emit detection laser beams with n different target wavelengths by driving signals; S4. The detection laser beam is emitted after being reflected by the rotating mirror module; S5. The emitted detection laser beam is reflected off the detection target to form a return beam, which then returns to the rotating mirror module. S6. The signal receiving module receives the reflected light beam from the rotating mirror module and converts it into an electrical signal. S7. The data processing module performs reflectance spectrum matching on the electrical signals received by the signal receiving module based on the reflectance spectrum library, thereby realizing the identification of the physical properties of the detected target and achieving the purpose of environmental perception. The VCSEL unit consists of four units, with wavelengths ranging from 1285-1405nm, 1025-1095nm, 880-950nm, and 780-850nm respectively, stacked from bottom to top.

2. The lidar system based on a multi-wavelength VCSEL laser as described in claim 1, characterized in that: Each VCSEL unit comprises, from bottom to top, an N-type DBR, an active region, an oxide confinement layer, and a P-type DBR, and a tunneling junction layer is provided between two adjacent VCSEL units.

3. A lidar system based on a multi-wavelength VCSEL laser as described in claim 2, characterized in that: The N-type DBR and P-type DBR of each VCSEL unit are periodic structures composed of alternating high-refractive-index thin films and low-refractive-index thin films; the number of periods of P-type DBR in the same VCSEL unit is less than the number of periods of N-type DBR; the number of periods of P-type DBR in the upper VCSEL unit is less than the number of periods of P-type DBR in the lower VCSEL unit.

4. A lidar system based on a multi-wavelength VCSEL laser as described in claim 1, characterized in that: Each VCSEL unit comprises, from bottom to top, a bottom N-type DBR, an active region, a buried tunnel junction, and a top N-type DBR, and the diameter of the buried tunnel junction of each VCSEL unit is equal, ranging from 5 to 150 μm.

5. A lidar system based on a multi-wavelength VCSEL laser as described in claim 4, characterized in that: Both the bottom N-type DBR and the top N-type DBR are periodic structures composed of alternating high-refractive-index thin films and low-refractive-index thin films; the number of cycles of the top N-type DBR in the same VCSEL cell is less than the number of cycles of the bottom N-type DBR; the number of cycles of the top N-type DBR in the upper VCSEL cell is less than the number of cycles of the top N-type DBR in the lower VCSEL cell.

6. A lidar system based on a multi-wavelength VCSEL laser as described in claim 1, characterized in that: Step S1 includes the following sub-steps: S11. Select typical targets in the application scenario of the lidar system as detection targets; S12. Classify the same detection target according to its physical properties based on color, material, and type; S13. Obtain the spectral reflectance characteristic curves of the same detection target with different physical properties within a set wavelength range through detection experiments, and store them in the reflectance spectrum library.

7. A lidar system based on a multi-wavelength VCSEL laser as described in claim 1, characterized in that: The signal transmission module includes a multi-wavelength VCSEL laser, a collimating optical element, and a diffractive optical element arranged sequentially along the optical path. The probe laser beam emitted by the multi-wavelength VCSEL laser is processed by the collimating optical element and the diffractive optical element before being emitted.

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