Laser, integrated chip, laser radar and preparation method of laser

Abstract

This application discloses a laser, an integrated chip, a lidar, and a method for fabricating the laser. The laser includes a first N-type layer, a first P-type layer, a first waveguide layer, and a laser body. The laser body includes a second N-type layer, a second waveguide layer, and a second P-type layer. The first P-type layer, the first waveguide layer, and the second N-type layer form a PIN junction. In a first operating mode, the refractive index of both the first waveguide layer in the PIN junction and the second waveguide layer in the laser body decreases, or the refractive index of both increases. In the first operating mode, the refractive index of the first waveguide layer in the PIN junction and the refractive index of the second waveguide layer in the laser body decrease or increase simultaneously, increasing the range of refractive index variation of the laser, increasing the frequency chirp range of the laser, and improving the frequency modulation bandwidth, thereby enhancing the range resolution capability of the lidar.

Description

Technical Field

[0001] This application relates to the field of optoelectronic device technology, and in particular to a laser, an integrated chip, a lidar, and a method for fabricating the laser. Background Art

[0002] Compared to traditional time-of-flight (TOF) pulse lidar, FMCW lidar offers several technical advantages: a large ranging range, high range resolution, Doppler velocities, small size, and ease of integration. Benefiting from these advantages, FMCW lidar has broad application prospects in high-precision mapping and autonomous driving. However, the limited range resolution of existing FMCW lidar technologies has hindered its development. Summary of the Invention

[0003] This application provides a laser, an integrated chip, a lidar, and a method for fabricating the laser, which addresses the problem of limited range resolution capability of FMCW lidar in related technologies.

[0004] In a first aspect, this application provides a laser, comprising a first N-type layer, a first P-type layer, a first waveguide layer, and a laser body stacked sequentially. The laser body includes a second N-type layer, a second waveguide layer, and a second P-type layer stacked sequentially on the side of the first waveguide layer opposite to the first P-type layer. The first P-type layer, the first waveguide layer, and the second N-type layer of the laser body combine to form a PIN junction.

[0005] The laser has a first operating mode in which the refractive index of the first waveguide layer in the PIN junction and the refractive index of the second waveguide layer in the laser body are both reduced; or, in the first operating mode, the refractive index of the first waveguide layer in the PIN junction and the refractive index of the second waveguide layer in the laser body are both increased.

[0006] Secondly, this application provides an integrated chip, including a chip body and the aforementioned laser; the chip body includes a substrate layer, a buried silicon oxide layer, and a transmission layer stacked together, the laser being disposed on the side of the transmission layer away from the buried silicon oxide layer, the transmission layer including a first portion and a second portion connected to the first portion, the first portion being directly opposite the laser, the second portion being located on the side of the emission section of the first waveguide layer of the laser, and the second portion including a coupler corresponding to the emission section and a third waveguide layer connected to the coupler, so that the coupler can couple the light from the emission section to the third waveguide layer.

[0007] Thirdly, this application provides a lidar, including the aforementioned integrated chip.

[0008] Fourthly, this application provides a method for fabricating a laser, comprising:

[0009] A first N-type layer is prepared, and a first P-type layer is formed on the first N-type layer; the first P-type layer has a second surface facing away from the first N-type layer;

[0010] A photoresist layer is coated on the second surface, and a grayscale mask is disposed on the side of the photoresist layer facing away from the second surface; wherein, the grayscale mask includes a transmittance gradient region;

[0011] The first P-type layer is exposed, developed, and etched using the grayscale mask to form a curved surface on the second surface of the first P-type layer at the corresponding transmittance gradient region.

[0012] A first waveguide layer, a second N-type layer, a second waveguide layer, and a second P-type layer are sequentially formed on the second surface.

[0013] The laser, integrated chip, lidar, and laser fabrication method disclosed in this application involve a second N-type layer, a first waveguide layer, and a first P-type layer forming a PIN junction within the laser body. When the laser is in a first operating mode, the refractive index of the first waveguide layer in the PIN junction decreases or increases synchronously with the refractive index of the second waveguide layer in the laser body. Compared to the decrease or increase in refractive index of a single laser body in the first operating mode in related technologies, this increases the range of refractive index variation and the frequency chirp range of the laser, thereby improving the frequency modulation bandwidth and enhancing the range resolution capability of the lidar. Attached Figure Description

[0014] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0015] Figure 1 This is a cross-sectional view of the laser provided in the embodiments of this application;

[0016] Figure 2 yes Figure 1 Cross-sectional view at point A-A';

[0017] Figure 3 yes Figure 1 The diagram shows a top view of the first waveguide layer in the laser.

[0018] Figure 4 This is a cross-sectional view of the integrated chip provided in the embodiments of this application;

[0019] Figure 5 This is a schematic diagram of the laser fabrication method provided in the embodiments of this application;

[0020] Figure 6 This is a flowchart of the laser fabrication method provided in the embodiments of this application. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0022] In the following description, when referring to the accompanying drawings, the same numbers in different drawings denote the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0023] In one aspect, embodiments of this application provide a laser 100. Please refer to... Figure 1 and Figure 2 The laser 100 may include a first N-type layer 110, a first P-type layer 120, a first waveguide layer 130 and a laser body 140 stacked in sequence. The laser body 140 includes a second N-type layer 141, a second waveguide layer 142 and a second P-type layer 143 stacked in sequence on the side of the first waveguide layer 130 away from the first P-type layer 120.

[0024] The second N-type layer 141 within the laser body 140, together with the first waveguide layer 130 and the first P-type layer 120, can form a PIN junction. The laser 100 has a first operating mode. In this first operating mode, the refractive index of both the first waveguide layer 130 in the PIN junction and the second waveguide layer 142 in the laser body 140 can be reduced; or, in the first operating mode, the refractive index of both the first waveguide layer 130 in the PIN junction and the second waveguide layer 142 in the laser body 140 can be increased. Thus, compared to the reduction or increase of the refractive index of a single laser body in the first operating mode in related technologies, the range of refractive index variation of the laser 100 is increased, the frequency chirp range of the laser 100 is increased, and the frequency modulation bandwidth is improved. The frequency modulation bandwidth B of the laser 100 satisfies the condition: Sr≥c / 2B, where Sr is the distance resolution; that is, after the frequency modulation bandwidth B of the laser 100 is increased, the value of the distance resolution Sr decreases, which can improve the distance resolution capability of the laser 100.

[0025] Optionally, to ensure that when the laser 100 is in the first operating mode, the refractive index of both the first waveguide layer 130 in the PIN junction and the refractive index of both the second waveguide layer 142 in the laser body 140 decreases or increases, the forward modulation signal of the PIN junction and the forward modulation signal of the laser body 140 can be in phase in the first operating mode. By controlling the forward modulation signal of the PIN junction and the forward modulation signal of the laser body 140, the refractive index of both the first waveguide layer 130 in the PIN junction and the refractive index of both the second waveguide layer 142 in the laser body 140 can decrease or increase simultaneously when the laser body 140 is in the first operating mode. This control method is simple and easy to operate.

[0026] Optionally, in the first operating mode, the forward modulation signal of the PIN junction and the forward modulation signal of the laser body 140 can be in phase as follows: In the first operating mode, the forward injection voltage of the PIN junction is positively correlated with time, and the forward injection current of the laser body 140 is positively correlated with time. When a forward voltage is applied to the PIN junction, holes in the P region and electrons in the N region enter the I region, that is, enter the first waveguide layer 130, increasing the carrier concentration and decreasing the refractive index in the I region. When a forward injection current is applied to the laser body 140, the carrier concentration in the active region changes with the modulation current, that is, the carrier concentration in the second waveguide layer 142 changes with the modulation current, thereby achieving modulation of the refractive index of the active region and ultimately realizing frequency-modulated continuous wave output. Thus, as the injection current of the laser body 140 increases and the forward voltage of the PIN junction increases, the carrier concentration of the first waveguide layer 130 and the second waveguide layer 142 will increase synchronously, and the refractive index will decrease synchronously. Ultimately, this increases the overall frequency chirp range of the laser 100, achieving a high frequency modulation bandwidth. In other words, this application adds a forward-injection type PIN modulator to the original frequency modulation of the laser body 140, increasing the range of carrier concentration and refractive index variation in the laser 100, ultimately improving the frequency modulation bandwidth.

[0027] The second N-type layer 141 has a first surface 1411 facing the second waveguide layer 142. The first waveguide layer 130 may include a curved waveguide segment 131 extending in a direction away from the first surface 1411. This achieves an anti-reflection effect, reducing the impact of reflected light on the linewidth broadening of the laser 100, maintaining the coherence of the laser 100, and increasing the detection range. Furthermore, the curved waveguide segment 131 can be formed directly during the epitaxial growth process of the laser 100, resulting in lower manufacturing costs and a smoother curved surface with lower transmission loss.

[0028] In this embodiment, an FMCW lidar requires a continuously varying frequency light source, typically ranging from several hundred MHz to tens of GHz. Modulation is generally performed using triangular or sawtooth waves, with modulation frequencies typically between 10 kHz and 100 kHz. Furthermore, FMCW lidar demands high continuity and linearity of the emitted signal to ensure a stable difference between the local oscillator and echo signals, preventing the introduction of other variables due to nonlinear waveform changes. Currently modulated distributed feedback (DFB) semiconductor lasers or external cavity diode lasers (ECDLs) are commonly used.

[0029] This application embodiment will be illustrated using a distributed feedback semiconductor laser as an example. The second waveguide layer 142 in the laser body 140 may include a quantum well layer 1421 and a grating layer 1422. The quantum well layer 1421 may be disposed between the second N-type layer 141 and the second P-type layer 143. The quantum well layer 1421 serves as the active region of the laser body 140, providing a gain medium for laser emission from the laser body 140. Specifically, when the laser 100 is operating, the light generated in the quantum well layer 1421 can enter the first waveguide layer 130 via evanescent wave coupling through the second N-type layer 141. The grating layer 1422 may be disposed between the quantum well layer 1421 and the second P-type layer 143, or between the quantum well layer 1421 and the second N-type layer 141, and the grating layer 1422 may have a grating pattern. The grating layer 1422 can serve as the mode selection area of ​​the laser body 140 and can be fabricated using holographic exposure and electron beam direct writing.

[0030] The first waveguide layer 130 can be a passive waveguide layer, which has lower optical loss, thereby improving the performance of the laser 100. The first waveguide layer 130 can be made of a material with a band gap larger than the wavelength of the emitted light, so that the material does not absorb the emitted light. That is, there is no material absorption loss when the emitted light propagates in the waveguide layer formed by this material.

[0031] In one exemplary embodiment, the first waveguide layer 130 can be composed of an undoped quaternary compound. For example, the first waveguide layer 130 can be composed of InGaAsP, and the second N-type layer 141 can be composed of InP, and the first P-type layer 120 can be composed of InP, thus forming a PIN junction. When a forward voltage is applied to the PIN junction, holes in the P-region and electrons in the N-region enter the I-region, thereby increasing the carrier concentration and decreasing the refractive index in the I-region.

[0032] It should be noted that the curved waveguide section 131 can be a portion extending in a curved direction within the first waveguide layer 130. For example, a portion extending in an arc within the first waveguide layer 130, or a portion extending in a wavy line within the first waveguide layer 130, etc.

[0033] Optionally, the first waveguide layer 130 may include an emission section 132, which may be configured as a curved waveguide section 131. Since light will be transmitted to the next device after passing through the emission section 132 of the first waveguide layer 130, configuring the emission section 132 of the first waveguide layer 130 as a curved waveguide section 131 can change the light emission direction of the first waveguide layer 130 compared to the straight waveguide layer in the related art, making the design of the laser 100 more flexible and enabling the miniaturization design of the lidar.

[0034] Specifically, the first N-type layer 110, the first P-type layer 120, the first waveguide layer 130, and the laser body 140 can be stacked sequentially along the first direction x. The first waveguide layer 130 can include an incident section 133 and an exit section 132 distributed along the second direction y, which can intersect with the first direction x. By setting the incident section 133 and the exit section 132 to be distributed along the second direction y, which intersects with the first direction x, when the exit section 132 is set as a curved waveguide section 131, the light output direction of the exit section 132 can be approximately located between the first direction x and the second direction y. This allows the emitted light to reach the next device that is stacked on the laser 100 along the first direction x and has a portion exposed above the laser 100, facilitating the integration of the laser 100 and the next device, and enabling the miniaturization design of the lidar. A more detailed explanation follows.

[0035] In one exemplary embodiment, the incident section 133 can be formed as a straight waveguide section, the exit section 132 can be formed as a curved waveguide section 131, and the first waveguide layer 130 can further include an intermediate section connecting the incident section 133 and the exit section 132, which can be formed as a wedge-shaped waveguide section. The design of the wedge-shaped waveguide section can improve the coupling effect of the optical mode field in the quantum well layer 1421 to the first waveguide layer 130, and can maximize the coupling of light into the first waveguide layer 130 and out through the exit section 132.

[0036] Specifically, the first waveguide layer 130 may include a strip waveguide, see [link to relevant documentation]. Figure 1 and Figure 3 ,in, Figure 3 This is a top view of the first waveguide layer 130. Figure 3The dashed lines in the diagram are added auxiliary lines. When the first waveguide layer 130 includes a strip waveguide, the first waveguide layer 130 may have a first end face 134 near the second N-type layer 141, a second end face 135 near the first P-type layer 120, and a first side face 136, a second side face 137, a third side face 138, and a fourth side face 139 connected between the first end face 134 and the second end face 135. The first side face 136 and the third side face 138 may be distributed opposite to each other along the second direction y. The second side face 137 may be connected between one end of the first side face 136 and one end of the third side face 138, and the fourth side face 139 may be connected between the other end of the first side face 136 and the other end of the third side face 138. The second side 137 may include a first sub-surface 1371 corresponding to the middle section, and the fourth side 139 may include a second sub-surface 1391 corresponding to the middle section. Along the second direction y, the distance between the first sub-surface 1371 and the second sub-surface 1391 may gradually increase or gradually decrease, thereby maximizing the coupling of light into the first waveguide layer 130. Figure 3 The diagram illustrates a scenario where the spacing between the first sub-surface 1371 and the second sub-surface 1391 can gradually decrease along the second direction y. It should be noted that the first waveguide layer 130 can also be a ridge waveguide, etc., and this embodiment does not limit this.

[0037] Please refer to it again. Figure 1 , Figure 1 The dashed lines in the diagram are added auxiliary lines. The laser 100 can be divided into: a straight waveguide region 150 corresponding to the incident section 133, a curved waveguide region 160 corresponding to the exit section 132, and a wedge-shaped waveguide region 170 corresponding to the intermediate section. The first N-type layer 110 may include a first sub-N-type layer located in the straight waveguide region 150, a second sub-N-type layer located in the wedge-shaped waveguide region 170, and a third sub-N-type layer located in the curved waveguide region 160. The first P-type layer 120 may include a first sub-P-type layer located in the straight waveguide region 150, a second sub-P-type layer located in the wedge-shaped waveguide region 170, and a third sub-P-type layer located in the curved waveguide region 160. The first waveguide layer 130 may include a straight waveguide section located in the straight waveguide region 150, a wedge-shaped waveguide section located in the wedge-shaped waveguide region 170, and a curved waveguide section 131 located in the curved waveguide region 160. The second N-type layer 141 may include a fourth sub-N-type layer located in the straight waveguide region 150, a fifth sub-N-type layer located in the wedge waveguide region 170, and a sixth sub-N-type layer located in the curved waveguide region 160.

[0038] The second waveguide layer 142 may include a first sub-waveguide layer located in the straight waveguide region 150 and a second sub-waveguide layer located in the wedge-shaped waveguide region 170. The second P-type layer 143 may include a fourth sub-P-type layer located in the straight waveguide region 150 and a fifth sub-P-type layer located in the wedge-shaped waveguide region 170. By configuring the second waveguide layer 142 and the second P-type layer 143 to correspond to the straight waveguide region 150 and the wedge-shaped waveguide region 170, but not to the curved waveguide region 160, a miniaturized design of the laser 100 can be achieved.

[0039] Similarly, the quantum well layer 1421 may include a first sub-quantum well layer 1421 located in the straight waveguide region 150 and a second sub-quantum well layer 1421 located in the wedge-shaped waveguide region 170. The grating layer 1422 may include a first sub-grating layer 1422 located in the straight waveguide region 150 and a second sub-grating layer 1422 located in the wedge-shaped waveguide region 170. By configuring the quantum well layer 1421 and the grating layer 1422 to not correspond to the curved waveguide region 160, the miniaturization design of the laser 100 can be further realized.

[0040] Optionally, the first N-type layer 110, the first P-type layer 120, the second N-type layer 141, and the second P-type layer 143 can all be made of InP material.

[0041] Secondly, embodiments of this application provide an integrated chip 10. Please refer to... Figure 4 The integrated chip 10 may include a chip body 200 and a laser 100. The chip body 200 may include a substrate layer 210, a buried silicon oxide layer 220, and a transmission layer 230 for transmitting the light from the laser 100 to the next device.

[0042] Specifically, the laser 100 is disposed on the side of the transmission layer 230 opposite to the buried silicon oxide layer 220. The transmission layer 230 may include a first portion 231 and a second portion 232 connected to the first portion 231. The first portion 231 may face the laser 100 directly, and the second portion 232 may be located on the side of the output section 132 of the first waveguide layer 130 of the laser 100 away from the incident section 133. The second portion 232 may include a coupler 2321 corresponding to the output section 132 and a third waveguide layer 2322 connected to the coupler 2321, so that the coupler 2321 can couple the light from the output section 132 to the third waveguide layer 2322. Distributing the transmission layer 230 to include the first portion 231 corresponding to the laser 100 facilitates the connection between the transmission layer 230 and the laser 100 and is easy to manufacture. The second part 232 of the transmission layer 230 is configured to include a coupler 2321 and a third waveguide layer 2322, so that the third waveguide layer 2322 can transmit light downward to the next device, so that the laser 100, the transmission layer 230 and the next device can be integrated on the same chip.

[0043] Among them, the next device can be a beam splitter, beam combiner, detector, optical phased array, etc. Compared with the separate setting and packaging of the transmitting laser and the receiving detector in related technologies, it can realize monolithic integrated optical components and realize the miniaturization design of lidar.

[0044] Optionally, the coupler 2321 may include a grating disposed in the second part 232; wherein the grating may include a plurality of slits distributed along the second direction y.

[0045] Optionally, the substrate 210 can be a silicon substrate, which allows the buried silicon oxide layer 220 to improve the voltage withstand capability of the device. In addition, the silicon substrate 210 can also share part of the voltage, which can further improve the voltage withstand capability of the device.

[0046] Thirdly, this application provides a lidar system. The lidar includes the aforementioned integrated chip 10. Because the integrated chip 10 can simultaneously integrate a transmitting laser 100 and a receiving detector, the lidar of this application is miniaturized. Optionally, the lidar can be an all-solid-state, integrated FMCW lidar, etc.

[0047] Fourthly, embodiments of this application provide a method for fabricating a laser 100. The laser 100 can be any of the lasers described above. Please refer to [link / reference]. Figure 5 and Figure 6 The method for fabricating the laser 100 may include the following steps: Step S02, fabricating a first N-type layer 110 and forming a first P-type layer 120 on the first N-type layer 110, the first P-type layer 120 having a second surface 121 facing away from the first N-type layer 110. Step S04, coating a photoresist layer 300 on the second surface 121, and setting a grayscale mask 400 on the side of the photoresist layer 300 facing away from the second surface 121; wherein, the grayscale mask 400 includes a transmittance gradient region 410. Step S06, exposing, developing, and etching the first P-type layer 120 using the grayscale mask 400, so that the second surface 121 of the first P-type layer 120 forms a curved surface at the corresponding transmittance gradient region 410. Step S08, sequentially forming a first waveguide layer 130, a second N-type layer 141, a second waveguide layer 142, and a second P-type layer 143 on the second surface 121.

[0048] In this embodiment, the transmittance of the grayscale mask 400 is set to a gradient, allowing different areas on the second surface 121 to be etched to varying degrees. For example, areas on the second surface 121 corresponding to areas with high transmittance of the grayscale mask 400 can be subject to greater etching, resulting in an extremely thin first P-type layer 120 at these locations. Conversely, areas on the second surface 121 corresponding to areas with low transmittance of the grayscale mask 400 can be subject to less etching, resulting in a thinner first P-type layer 120 at these locations. This, in turn, allows the area on the second surface 121 corresponding to the transmittance gradient region 410 to form a curved surface. Using the transmittance gradient region 410 to form a curved surface on the first P-type layer 120 results in a simple forming method, low manufacturing cost, and good smoothness of the curved surface.

[0049] In one exemplary embodiment, the transmittance gradient region 410 of the grayscale mask 400 can be located near the edge of the second surface 121, and the transmittance of the transmittance gradient region 410 can gradually increase from the inside of the second surface 121 to the edge of the second surface 121. This allows the first waveguide layer 130 disposed on the first P-type layer 120 to include a curved waveguide segment 131 extending away from the second surface 121, achieving an anti-reflection effect, reducing the impact of reflected light on the linewidth broadening of the laser 100, maintaining the coherence of the laser 100, and increasing the detection distance. Furthermore, the curved waveguide segment 131 can be formed directly during the epitaxial growth process of the laser 100, resulting in lower manufacturing costs and a smoother curved surface with lower transmission loss.

[0050] In one exemplary embodiment, the formation of the second waveguide layer 142 may include: sequentially forming a quantum well layer 1421 and a grating layer 1422 on the side of the second N-type layer 141 facing away from the first waveguide layer 130, and etching the grating layer 1422 to form a grating pattern. At this time, the second N-type layer 141, quantum well layer 1421, grating layer 1422, and second P-type layer 143 can substantially form the distributed feedback semiconductor laser 100 (DFB) in the prior art.

[0051] The above-disclosed embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of this application. Therefore, any equivalent variations made in accordance with the claims of this application shall still fall within the scope of this application.

Claims

1. A laser, characterized in that, The device includes a first N-type layer, a first P-type layer, a first waveguide layer, and a laser body, which are stacked sequentially. The laser body includes a second N-type layer, a second waveguide layer, and a second P-type layer, which are stacked sequentially on the side of the first waveguide layer opposite to the first P-type layer. The first P-type layer, the first waveguide layer, and the second N-type layer of the laser body combine to form a PIN junction. The laser has a first operating mode in which the refractive index of the first waveguide layer in the PIN junction and the refractive index of the second waveguide layer in the laser body are both reduced; or, in the first operating mode, the refractive index of the first waveguide layer in the PIN junction and the refractive index of the second waveguide layer in the laser body are both increased.

2. The laser as described in claim 1, characterized in that, In the first operating mode, the forward modulation signal of the PIN junction is in phase with the forward modulation signal of the laser body.

3. The laser as described in claim 2, characterized in that, In the first operating mode, the forward injection voltage of the PIN junction is positively correlated with time, and the forward injection current of the laser body is positively correlated with time.

4. The laser as described in claim 1, characterized in that, The second N-type layer has a first surface facing the second waveguide layer, and the first waveguide layer includes a curved waveguide segment extending in a direction away from the first surface.

5. The laser as described in claim 4, characterized in that, The first N-type layer, the first P-type layer, the first waveguide layer, and the laser body are stacked sequentially along a first direction. The first waveguide layer includes an incident section and an exit section distributed along a second direction. The second direction intersects with the first direction, and the exit section is formed as the curved waveguide section.

6. The laser as described in claim 5, characterized in that, The incident section is formed as a straight waveguide section, and the first waveguide layer further includes an intermediate section connecting the incident section and the exit section, the intermediate section being formed as a wedge-shaped waveguide section.

7. The laser as claimed in claim 6, characterized in that, The laser has a straight waveguide region corresponding to the incident section, a curved waveguide region corresponding to the exit section, and a wedge-shaped waveguide region corresponding to the intermediate section. The first N-type layer includes a first sub-N-type layer located in the straight waveguide region, a second sub-N-type layer located in the wedge-shaped waveguide region, and a third sub-N-type layer located in the curved waveguide region; The first P-type layer includes a first sub-P-type layer located in the straight waveguide region, a second sub-P-type layer located in the wedge waveguide region, and a third sub-P-type layer located in the curved waveguide region; The first waveguide layer includes the straight waveguide segment located in the straight waveguide region, the wedge waveguide segment located in the wedge waveguide region, and the curved waveguide segment located in the curved waveguide region; The second N-type layer includes a fourth sub-N-type layer located in the straight waveguide region, a fifth sub-N-type layer located in the wedge waveguide region, and a sixth sub-N-type layer located in the curved waveguide region; The second waveguide layer includes a first sub-waveguide layer located in the straight waveguide region and a second sub-waveguide layer located in the wedge-shaped waveguide region; The second P-type layer includes a fourth sub-P-type layer located in the straight waveguide region and a fifth sub-P-type layer located in the wedge waveguide region.

8. The laser as claimed in claim 1, characterized in that, The second waveguide layer includes: A quantum well layer is disposed between the second N-type layer and the second P-type layer; A grating layer is disposed between the quantum well layer and the second P-type layer or between the quantum well layer and the second N-type layer, and the grating layer is provided with a grating pattern.

9. An integrated chip, characterized in that, Includes the chip body and the laser as described in any one of claims 1 to 8; The chip body includes a substrate layer, a buried silicon oxide layer, and a transmission layer stacked together. The laser is disposed on the side of the transmission layer away from the buried silicon oxide layer. The transmission layer includes a first part and a second part connected to the first part. The first part is directly opposite the laser. The second part is located on the side of the emission section of the first waveguide layer of the laser. The second part includes a coupler corresponding to the emission section and a third waveguide layer connected to the coupler, so that the coupler can couple the light from the emission section to the third waveguide layer.

10. The integrated chip as described in claim 9, characterized in that, The coupler includes a grating disposed in the second part, the grating including a plurality of spaced slits.

11. A lidar, characterized in that, Includes the integrated chip as described in claim 9 or 10.

12. A method for preparing a laser according to any one of claims 1 to 8, characterized in that, include: Prepare a first N-type layer, and form a first P-type layer on the first N-type layer; The first P-type layer has a second surface that is opposite to the first N-type layer; A photoresist layer is coated on the second surface, and a grayscale mask is disposed on the side of the photoresist layer facing away from the second surface; wherein, the grayscale mask includes a transmittance gradient region; The first P-type layer is exposed, developed, and etched using the grayscale mask to form a curved surface on the second surface of the first P-type layer at the corresponding transmittance gradient region. A first waveguide layer, a second N-type layer, a second waveguide layer, and a second P-type layer are sequentially formed on the second surface.

13. The preparation method according to claim 12, characterized in that, The transmittance gradient area of ​​the grayscale mask is located near the edge of the second surface, and the transmittance gradually increases from the inside of the second surface to the edge of the second surface.

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