A chip-level acousto-optic beam controller, a laser radar system and a frequency-angle resolution method

Abstract

This application relates to the fields of integrated photonics and optoelectronics, and more specifically, to a chip-level acousto-optic beam controller, a lidar system, and a frequency-angle resolution method. It utilizes apodization / chirping and weighted design of an interdigital transducer to make the wave vector of the equivalent acoustic grating monotonically change with the driving frequency, thus establishing the emission angle. θ 1. Mapping with the radio frequency enables frequency-angle resolution; and a focusing / tilting apodization / chirping IDT is installed near the output end to apply a longitudinal phase distribution to the output wavefront, generating a controllable horizontal output angle. θ 2. Furthermore, a 1×N on-chip beam splitter is used to distribute the optical power to N parallel acousto-optic channels, significantly improving point throughput and field of view coverage. The lidar system can be combined with FMCW, using coherent reception to calculate the distance by echo beat frequency, and using the driving frequency to determine the angle, achieving all-solid-state, low-power, high-speed, large-field-of-view 3D imaging.

Description

Technical Field

[0001] This application relates to the fields of integrated photonics and optoelectronics, and more specifically, to a chip-level acousto-optic beam controller, a lidar system, and a frequency-angle resolution method. Background Technology

[0002] Optical detection and ranging (LiDAR), with its superior imaging resolution and ranging range, is rapidly becoming an indispensable optical sensing technology for intelligent automated systems, including autonomous vehicles and robots. A key to developing next-generation LiDAR systems lies in the need for a non-mechanical beam control system capable of scanning laser beams in space. Currently, diffraction methods such as optical phased arrays (OPA) and spatial light modulators (SLM) generally require independently controlled, large-scale discrete subwavelength arrays of components, resulting in complex control systems and manufacturing processes. Acousto-optic beam control (AOBS) technology utilizes sound waves propagating in materials to mechanically cause fluctuations in their refractive index, thereby generating a moving refractive index grating. Utilizing the physical properties of Brillouin scattering, beams deflected at different angles are marked with unique frequency shifts. However, traditional on-chip acousto-optic deflection devices based on single materials are limited by the inherent properties of the material; high values ​​cannot be simultaneously achieved for elastic-optical properties, piezoelectric properties, and refractive index. More importantly, current on-chip acousto-optic beam control systems typically rely on a single microwave driver for scanning in one dimension, often requiring external mechanical galvanometers or other equipment to achieve vertical scanning, thus failing to achieve fully integrated three-dimensional solid-state scanning. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing on-chip acousto-optic beam control, which cannot achieve fully integrated three-dimensional solid-state scanning. It provides a chip-level acousto-optic beam controller, a lidar system, and a frequency-angle resolution method. The chip-level acousto-optic beam controller achieves fully integrated three-dimensional solid-state scanning, thereby further improving the accuracy and stability of scanning.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A chip-level acousto-optic beam controller is provided, comprising: Insulating substrate 101; A lithium niobate thin film layer disposed on the insulating substrate 101 is used for electro-acoustic conversion; A chalcogenide glass waveguide layer disposed on the lithium niobate thin film layer is used to form an acousto-optic interaction region; A first apodization / chirping IDT is disposed on the lithium niobate thin film layer to excite surface acoustic waves / Love waves and form an equivalent acoustic grating in the acousto-optic region; An incident grating coupler, disposed on the chalcogenide glass waveguide layer, is used to deflect the outgoing light exiting the incident grating coupler relative to the X direction in the XZ plane. i 1. With driving frequency f RF Monotonic variation to establish a frequency-angle mapping; The second apodization / chirped IDT, disposed on the lithium niobate thin film layer and arranged in the region surrounding the exit end of the incident grating coupler, is used to apply a transverse phase distribution to the outgoing wavefront in the XY plane to generate a controllable additional deflection angle relative to the X direction in the XY plane. i 2. Or sidelobe suppression.

[0005] This invention discloses a chip-level acousto-optic beam controller that achieves monotonic frequency-angle mapping and low sidelobe vertical scanning through a first apodization / chirping IDT; a second apodization / chirping IDT is introduced at the emission end to apply a longitudinal phase distribution to the emission wavefront, generating a controllable horizontal emission angle. i 2; This invention provides a chip-level acousto-optic beam controller that is calibrated on-chip, has high stability, and achieves fully integrated three-dimensional solid-state scanning.

[0006] Furthermore, both the first apodization / chirped IDT and the second apodization / chirped IDT employ a combination structure of envelope weighting and electrode periodic chirping to achieve a bandwidth of ≥10% while maintaining high diffraction efficiency and suppressing angular sidelobes; wherein, the second apodization / chirped IDT employs a focused or tilted apodization / chirped IDT.

[0007] Furthermore, the second apodization / chirping IDT employs an arc-shaped, elliptical, or phase-coded structure, making the additional deflection angle... i 2. The setting is available in the range of 0~10°.

[0008] Furthermore, it also includes acoustic absorption or isolation structures disposed around the acousto-optic interaction area to suppress acoustic reflection and channel crosstalk; it also includes an on-chip monitoring and calibration unit for acquiring the emission angle and establishing / updating... f RF – i 1. Mapping relationship to compensate for temperature and process drift.

[0009] Furthermore, the chalcogenide glass waveguide layer uses one or more of the following chalcogenide glass materials: As2S3, As2Se3, Ge–As–Se, or Ge–Sb–Se.

[0010] Furthermore, the thicknesses of the lithium niobate thin film layer and the chalcogenide glass waveguide layer satisfy the Love wave mode dispersion condition, so as to achieve upper coupling of acoustic energy and maximum overlap with the optical mode.

[0011] The present invention also provides a multi-channel chip-level acousto-optic beam controller, including 1×N on-chip beam splitters, wherein N≥2, for distributing incident light to N parallel acousto-optic channels, each of the parallel acousto-optic channels being provided with the chip-level acousto-optic beam controller described above.

[0012] Furthermore, the parallel acousto-optic channels are spliced ​​in the angular domain to expand the total field of view; or, multiple independent angles of outgoing beams are generated in a multi-tone parallel manner within the same field of view.

[0013] The present invention also provides a lidar system, comprising: The light source and electro-optic modulation module are used to realize the frequency modulated continuous wave (FMCW) system; Such as the chip-level acousto-optic beam controller described above; The radio frequency synthesis and control module is used to apply programmable drivers of single tone, frequency sweep or multiple tone to the first apod / chirp IDT and the second apod / chirp IDT; It also includes a coherent receiving and signal processing module, which analyzes the beat frequency signal to obtain distance information and determines the azimuth angle using the drive frequency or sub-band index, thereby achieving three-dimensional imaging.

[0014] The present invention provides a lidar system that, based on the frequency-angle mapping of the chip-level acousto-optic beam controller described above, maps the driving frequency to the emission angle, uses coherent beat frequency to obtain the echo intermediate frequency signal to calculate distance information, and determines the angle information by the driving frequency or sub-band index.

[0015] Furthermore, the coherent receiving and signal processing module performs spectral analysis or two-dimensional Fourier transform on the beat frequency signal to obtain distance and angular dimension information, respectively.

[0016] Furthermore, the radio frequency synthesis and control module outputs multiple non-overlapping or partially overlapping RF audio signals, thereby achieving multi-beam parallel scanning.

[0017] This invention also includes a frequency-angle resolution method, employing the chip-level acousto-optic beam controller described above, comprising the following steps: The first apodization / chirped IDT is driven by a preset single-tone, sweep, or multi-tone RF signal, thereby increasing the deflection angle of the emitted beam. i 1 and driving frequency f RF Establish a monotonic frequency-angle mapping relationship; The second apodization / chirped IDT is driven / disdriven by a preset single-tone, sweep, or multi-tone RF signal to set or switch the additional deflection angle of the emitted light in the XY plane. i 2; The branch emitting the laser is used as the local oscillator, and coherently beats with the echo to obtain the intermediate frequency signal; The target distance is determined based on the beat frequency component of the intermediate frequency signal; Based on the frequency-angle mapping relationship, the target azimuth angle is determined using the frequency information of the intermediate frequency signal.

[0018] Furthermore, by applying amplitude or phase weighting to the RF signal to suppress angular sidelobes and by pre-distortion compensation for diffraction efficiency at different frequencies, a larger field of view can be achieved.

[0019] Furthermore, the method of the present invention can support multi-tone parallel transmission and echo separation, enabling simultaneous imaging from multiple angles.

[0020] Compared with the prior art, the beneficial effects of the present invention are: 1. The device features high coupling and low power consumption: the lithium niobate thin film layer has a high kJ / L NOI. 2 When combined with the high acousto-optic coefficient of chalcogenide glass, Love wave upcouples acoustic energy to the waveguide, significantly improving Bragg diffraction efficiency and reducing RF power consumption. 2. Achieves a balance between wide field of view and high resolution: First apodization / chirped IDT obtains a broadband monotonic F–θ mapping, and the FOV is further extended through multi-channel / segmented stitching; 3. Implements native support for parallel multi-channel transmission: significantly improves throughput and frame rate; 4. Three-dimensional wavefront control was achieved: By introducing a second apodization / chirped IDT at the exit end, horizontal deflection / shaping was achieved, resulting in a three-dimensional scan with low sidelobes and high extinction. 5. On-chip calibrable and highly stable: Acousto-optic absorption and monitoring ports suppress echoes and thermal drift, ensuring angular linearity and repeatability; compact structure, no inertia, easy for mass production and packaging.

[0021] In summary, the chip-level acousto-optic beam controller, lidar system, and frequency-angle resolution method of this invention utilize apodization / chirp and weighted design of interdigital transducers to make the wave vector of the equivalent acoustic grating monotonically change with the driving frequency, thereby establishing the emission angle. i 1. Mapping with the radio frequency enables frequency-angle resolution; and a focusing / tilting apodization / chirping IDT is installed near the output end to apply a longitudinal phase distribution to the output wavefront, generating a controllable horizontal output angle. i 2. Furthermore, a 1×N on-chip beam splitter is used to distribute the optical power to N parallel acousto-optic channels, significantly improving point throughput and field of view coverage. The lidar system can be combined with FMCW, using coherent reception to calculate the distance by echo beat frequency, and using the driving frequency to determine the angle, achieving all-solid-state, low-power, high-speed, large-field-of-view 3D imaging. Attached Figure Description

[0022] Figure 1This is a schematic diagram of the first-view structure of a chip-level acousto-optic beam controller in one embodiment; in the figure, X and Y represent two orthogonal directions in the chip plane, with the X-axis parallel to the direction of sound wave propagation; the Z-axis is perpendicular to the chip plane and points upwards; the XZ plane is the azimuth scanning plane. i The plane containing 1; the XY plane scanning plane is i The plane containing 2; i 1 represents the deflection angle of the emitted light in the XZ azimuth plane caused by acousto-optic diffraction (as the angle increases with the direction of light movement). f RF (Monotonous change); i 2. Additional deflection angle or lateral phase shaping amount generated in the XY plane by the second apodization / chirped IDT; Figure 2 This is a schematic diagram of the second-view structure of a chip-level acousto-optic beam controller in one embodiment; Figure 3 This is a schematic diagram of the structure of a multi-channel chip-level acousto-optic beam controller in one embodiment; Figure 4 This is a schematic diagram of the lidar system in another embodiment; Figure 5 This is a flowchart illustrating a frequency-angle resolution method in one embodiment; Figure 6 The optical field distribution of a 1550nm optical signal in the device is shown in Example 3. Figure 7 The results show the propagation intensity distribution of surface acoustic waves in the device in Example 3.

[0023] In the attached figures: 101, insulating substrate; 102, lithium niobate thin film layer; 103, chalcogenide glass waveguide layer; 104, first apodization / chirped IDT; 105, incident grating coupler; 106, second apodization / chirped IDT; 107, acoustic absorption or isolation structure; 201, beam splitter; 202, parallel acousto-optic channel; 301, light source and electro-optic modulation module; 302, radio frequency synthesis and control module; 303, coherent reception and signal processing module; 311, laser; 312, electro-optic modulation module. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only, representing schematic diagrams rather than actual physical objects, and should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0025] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0026] Example 1 This embodiment is a first embodiment of a chip-level acousto-optic beam controller, such as... Figure 1 and Figure 2 As shown, it includes: Insulating substrate 101; A lithium niobate thin film layer 102 disposed on an insulating substrate 101 is used for electro-acoustic conversion; the thickness of the lithium niobate thin film layer 102 is 100nm~600nm; A chalcogenide glass waveguide layer 103 disposed on a lithium niobate thin film layer 102 is etched to form an optical waveguide and an acousto-optic interaction region. The waveguide width is 300nm~30um and the height is 200~500nm, and it operates in the communication band. The first apodization / chirping IDT104 is disposed on the lithium niobate thin film layer 102 with an electrode thickness of 80nm~200nm. It is used to excite surface acoustic waves / Love waves of 80 MHz~2 GHz and form an equivalent acoustic grating in the acousto-optic region. An incident grating coupler 105 is disposed on the chalcogenide glass waveguide layer 103. The light beam is incident through the grating coupler, and its period and tilt angle are designed in conjunction with the acoustic wave vector range to ensure that the outgoing light exiting the incident grating coupler 105 is deflected relative to the X direction in the XZ plane. i 1. With driving frequency f RF Monotonic variation to establish a frequency-angle mapping; The second apodization / chirping IDT 106, located on the lithium niobate thin film layer 102, is arranged in the region surrounding the exit end of the incident grating coupler 105. It is used to apply a transverse phase distribution to the outgoing wavefront in the XY plane to generate a controllable additional deflection angle relative to the X direction in the XY plane. i 2. Or sidelobe suppression.

[0027] In this embodiment, both the first apodization / chirped IDT 104 and the second apodization / chirped IDT 106 adopt a combination structure of envelope weighting and electrode periodic chirping to obtain a bandwidth of ≥10% while maintaining high diffraction efficiency and suppressing angular sidelobes; wherein, the second apodization / chirped IDT 106 adopts a focusing or tilting type apodization / chirped IDT.

[0028] In this embodiment, the second apodization / chirping IDT106 employs an arc-shaped, elliptical, or phase-coded structure to enable an additional deflection angle. i 2. The setting is available in the range of 0~10°.

[0029] In this embodiment, an acoustic absorption or isolation structure 107 is also included, disposed on the outer periphery of the acousto-optic interaction area, to suppress acoustic reflection and channel crosstalk; an on-chip monitoring and calibration unit is also included, used to acquire the emission angle and establish / update the calibration. f RF – i 1. Mapping relationship to compensate for temperature and process drift.

[0030] In this embodiment, the chalcogenide glass waveguide layer 103 uses one or more of the following chalcogenide glass materials: As2S3, As2Se3, Ge–As–Se, or Ge–Sb–Se.

[0031] Furthermore, the thicknesses of the lithium niobate thin film layer 102 and the chalcogenide glass waveguide layer 103 satisfy the Love wave mode dispersion condition, so as to achieve maximum acoustic energy coupling and maximum overlap with the optical mode.

[0032] This embodiment presents a chip-level acousto-optic beam controller, LNOI high k 2 Superimposed with the high acousto-optic coefficient of chalcogenide glass, the Love wave topcouples acoustic energy to the waveguide, significantly improving Bragg diffraction efficiency and reducing RF power consumption. A monotonic frequency-angle mapping and low sidelobe vertical scanning are achieved through a first apodization / chirping IDT104. A second apodization / chirping IDT106 is introduced at the emission end to apply a longitudinal phase distribution to the emission wavefront, generating a controllable horizontal emission angle. i 2; This invention provides a chip-level acousto-optic beam controller that is calibrated on-chip, has high stability, and achieves fully integrated three-dimensional solid-state scanning; the acoustic absorption and monitoring ports suppress echoes and thermal drift, ensuring angular linearity and repeatability; the structure is compact, inertial-free, and easy to mass-produce and package.

[0033] Example 2 This embodiment is a second embodiment of a chip-level acousto-optic beam controller. Similar to the first embodiment, this embodiment heterogeneously integrates a chalcogenide glass waveguide on a lithium niobate thin film layer 102. The lithium niobate thin film layer 102 has a thickness of 100nm~600nm. The chalcogenide glass waveguide uses As2S3, As2Se3, Ge–As–Se, or Ge–Sb–Se materials. The waveguide width is 300nm~30μm, the height is 200nm~500nm, and the operating wavelength is in the communication band. A first apodization / chirping IDT104 (electrode thickness 80~200 nm) excites an 80MHz~2GHz SAW / Love wave. Through surface acoustic wave dispersion design, the SAW wave phase velocity is lower than the intrinsic SAW phase velocity of the lithium niobate thin film layer 102, resulting in upward coupling of acoustic energy and maximum overlap with the optical mode.

[0034] A focusing / tilting type second apodization / chirped IDT106 is arranged near the output end and driven to operate at a specific frequency or narrow band. A transverse phase distribution is applied to the output wavefront in the XY plane, resulting in a controllable additional deflection angle relative to the X direction in the XY plane. i 2. Or a shaping wavefront with sidelobe suppression. Acoustic absorption / isolation structures are placed on the periphery of the acousto-optic interaction zone to reduce reflection and crosstalk.

[0035] During operation, the RF source sweeps or multi-tone drives the first apodization / chirping IDT104, and the deflection angle of the emitted light in the XZ azimuth plane is determined. i 1. Achieve XZ plane azimuth scanning by varying the frequency; for 3D scanning, superimpose and drive a second IDT to set the desired orientation. i 2, or in multiple presets i Switch between 2 and 3.

[0036] Example 3 This embodiment is a third embodiment of a chip-level acousto-optic beam controller. This embodiment is similar to the first embodiment, and provides a simulation experiment for the chip-level acousto-optic beam controller provided in the first embodiment.

[0037] In order to verify the working principle and effect of the chip-level acousto-optic beam controller provided in Example 1, this embodiment uses the finite-difference time-domain (FDTD) method to perform numerical simulation analysis on the light field propagation process in the device.

[0038] The simulation model includes an insulating substrate 101, a lithium niobate thin film layer 102, a chalcogenide glass waveguide layer 103, an incident grating coupler 105, and a tilted second apodization / chirped IDT 106 disposed on the device surface. (The first apodization / chirped IDT 104 is omitted in this simulation experiment; the main purpose is to verify that the device can achieve an additional deflection angle relative to the X-axis in the XY plane.) i2) The second apodization / chirping IDT106 period is designed to be 3.2 μm and is tilted at a certain angle relative to the direction of light propagation. When an 884 MHz radio frequency drive signal is applied to the IDT, a stable propagating surface acoustic wave is excited on the lithium niobate surface, and a periodically changing strain field is formed in the chalcogenide waveguide region.

[0039] like Figure 6 The figure shows the propagation optical field distribution of a 1550nm optical signal in the device. Simulation results show that when the incident light enters the chalcogenide waveguide region, it initially propagates stably along its original direction. When the light wave propagates to the surface acoustic wave region, a dynamic acousto-optic grating is formed due to the periodic refractive index modulation generated by the acoustic wave, resulting in momentum exchange between the incident light and the acoustic wave.

[0040] When the Bragg matching condition is met: 2 n eff Λ sinth B = ml in, n eff Λ represents the effective refractive index of the waveguide mode; Λ represents the period of the acousto-optic grating. i B For the Bragg diffraction angle; l The wavelength of the incident light; m This refers to the diffraction order.

[0041] At this point, the incident light is effectively coupled to the diffraction mode and output along the new propagation direction.

[0042] From the appendix Figure 6 It can be observed that: The light beam propagates in a straight line before entering the acousto-optic interaction region; within the acousto-optic interaction region, the light field gradually shifts towards the diffraction direction; as the propagation distance increases, the diffracted light power continuously increases, while the light power in the original propagation direction gradually decreases; a diffracted beam that deviates significantly from the initial propagation direction is formed at the output end; the diffracted beam profile is continuous and the boundary is clear, indicating that the acousto-optic coupling process is stable and has high conversion efficiency.

[0043] Analysis of the acoustic-optic coupling mechanism: Because this embodiment employs an inclined IDT structure, the propagation direction of the excited surface acoustic waves forms a non-zero angle with the propagation direction of the light. The resulting dynamic acousto-optic grating has a definite spatial frequency vector, which can provide additional transverse momentum compensation for the light field.

[0044] When the phase-matching condition is met, efficient energy exchange occurs between the light wave and the sound wave, causing the propagating beam to deviate from its original propagation direction and form Bragg diffraction output. Compared with traditional electro-optic deflection methods, this invention utilizes dynamic refractive index modulation generated by surface acoustic waves to achieve beam control, which has advantages such as low driving power consumption, high deflection efficiency, strong reconfigurability, and easy on-chip integration.

[0045] Simulation results demonstrate that, within the chalcogenide / lithium niobate heterostructure platform, a uniform and stable dynamic acousto-optic grating can be formed in the waveguide region by exciting 884 MHz surface acoustic waves through a tilted second apodization / chirped IDT106 structure with a period of 3.2 μm. When 1550 nm incident light passes through this region, the beam satisfying the Bragg diffraction condition can be efficiently deflected, producing a significant angular change.

[0046] The results show that the chip-level acousto-optic beam controller provided by the present invention can utilize the strong interaction between surface acoustic waves and light waves to realize on-chip beam scanning, optical switching, beam routing and reconfigurable photonic integration, providing an effective technical solution for the miniaturization and high performance of integrated acousto-optic devices.

[0047] Simulation of excitation and propagation of surface acoustic waves in a device: To verify the feasibility of the heterogeneous integrated acousto-optic modulation structure of chalcogenide materials / lithium niobate proposed in this invention, the surface acoustic wave (SAW) generated by the excitation of the interdigital transducer (IDT) was modeled and analyzed using finite element multiphysics simulation software.

[0048] The simulation model includes an insulating substrate 101, a lithium niobate thin film layer 102, a chalcogenide glass waveguide layer 103, an incident grating coupler 105, and a first apodization / chirped IDT 104 and a second apodization / chirped IDT 106 disposed on the device surface. The two IDTs employ a periodic interdigitated electrode design with a period of 3.2 μm. Based on the relationship between the surface acoustic wave phase velocity and the excitation frequency: f = v SAW / Λ In the formula, f For sound wave frequency, v SAW Let Λ be the surface acoustic wave propagation speed, and Λ be the IDT period.

[0049] In the simulation, an 884 MHz radio frequency AC voltage excitation was applied to excite surface acoustic waves propagating along the device surface. Acoustic absorption or isolation structures 107 were used at the model boundary to reduce the influence of reflected sound waves on the results, and the material parameters were set using the actual physical parameters of chalcogenide materials and lithium niobate.

[0050] Simulation Result Analysis: like Figure 7 The figure shows the intensity distribution of surface acoustic waves (SAWs) propagating in the device. The simulation results show that the acoustic waves generated by the IDT excitation can propagate stably along the predetermined direction and form a significant energy concentration distribution in the propagation region. The sound field energy is mainly confined to the vicinity of the device surface, consistent with the propagation characteristics of SAWs.

[0051] As the propagation distance increases, the acoustic wave front maintains good integrity, with no obvious scattering or distortion, indicating that the designed IDT structure can achieve efficient acoustic excitation and directional propagation. Simultaneously, the acoustic field and the optical waveguide region exhibit good spatial overlap, providing a foundation for subsequent high-efficiency acousto-optic coupling modulation.

[0052] like Figure 7 The right side shows a strain tensor distribution contour map in a heterogeneous integrated structure. The red and blue areas in the figure correspond to the positive and negative strain regions, respectively, indicating that an elastic strain field that varies periodically along the propagation direction is formed under IDT excitation.

[0053] Simulation results show: 1. When the IDT operates at a frequency of 884 MHz, a stable and continuous surface acoustic wave is generated on the device surface; 2. The strain field exhibits a distinct periodic distribution along the propagation direction, and its period matches the IDT design period; 3. Within the effective propagation area of ​​sound waves, the amplitude of the strain tensor is uniformly distributed, and the consistency between each acoustic cycle is good. 4. The strain energy is mainly concentrated on the surface of the device and in the waveguide region, indicating that the acoustic field can effectively act on the chalcogenide waveguide material; 5. No obvious mode distortion or local energy accumulation was observed, indicating that the designed structure can achieve high-quality surface acoustic wave propagation.

[0054] In summary, the simulation results demonstrate that the IDT structure with a period of 3.2 μm, employed in this invention, can generate spatially uniform and stably propagating surface acoustic waves on the chalcogenide / lithium niobate heterostructure integrated platform designed in this invention under 884 MHz RF excitation. The resulting periodic strain field can effectively modulate the refractive index distribution in the waveguide region, thereby enhancing the acousto-optic interaction efficiency. This provides a technological foundation for realizing high-performance acousto-optic modulators, reconfigurable photonic devices, and integrated RF photonic devices.

[0055] Example 4 This embodiment is a first embodiment of a multi-channel chip-level acousto-optic beam controller. Based on the chip-level acousto-optic beam controller provided in Embodiment 1, this embodiment provides a multi-channel chip-level acousto-optic beam controller, such as... Figure 3 and Figure 4 As shown, it includes a 1×N on-chip beam splitter 201, where N≥2, used to distribute incident light to N parallel acousto-optic channels 202, each of which is equipped with the above chip-level acousto-optic beam controller.

[0056] In this embodiment, the parallel acousto-optic channels 202 are spliced ​​in the angular domain to expand the total field of view; or, multiple independent angles of outgoing beams are generated in the same field of view in a multi-tone parallel manner.

[0057] This embodiment provides a multi-channel chip-level acousto-optic beam controller, which is based on the controller in Embodiment 1. It uses a 1×N on-chip beam splitter 201 to distribute optical power to N parallel acousto-optic channels 202, significantly improving point throughput and field of view coverage.

[0058] Example 5 This embodiment is a second embodiment of a multi-channel chip-level acousto-optic beam controller. Similar to embodiment three, this embodiment also uses a 1×N beam splitter 201 to distribute the incident light to N parallel acousto-optic channels 202. Each parallel acousto-optic channel 202 includes the chip-level acousto-optic beam controller from embodiment one. In this embodiment, the following can be selected: (1) Multi-wave parallel: Multiple frequency sound waves are injected into the same parallel acousto-optic channel 202. f i ,get{ i 1, i Multiple beams in parallel; (2) Multi-channel splicing: Each parallel acousto-optic channel 202 is set with different center frequency bands or different output grating coupling angles, so that its F–θ segment is spliced ​​in the angular domain to expand the total FOV; (3) Combination mode: Simultaneously adopts multiple sound waves + multiple channels to improve throughput and achieve a large field of view coverage.

[0059] In use, a narrow-linewidth laser 311 and an electro-optic modulation module 312 are employed to implement FMCW or pulsed modulation. The radio frequency synthesis and control module 302 provides programmable multi-frequency sweeps. The coherent receiving and signal processing module 303 performs spectral / two-dimensional FFT processing on the echo beat frequency to obtain a distance-angle-intensity data cube. Monitoring ports can be configured on-chip to establish and update data. f RF – i 1. Lookup table with temperature compensation.

[0060] Example 6 This embodiment is based on the chip-level acousto-optic beam controller provided in Embodiment 1 or Embodiment 4, and provides optional parameter settings, optional features and variations of the controller.

[0061] Typical parameters: Lithium niobate thin film layer 102 thickness 300nm; IDT electrode thickness 120 nm, period 0.8–3 μm; RF band 0.1~1.8 GHz; single-channel effective acoustic aperture A=0.5~1.5 mm; i 1. Linear segment ≥ 10°.

[0062] Angular resolution by Δ f • A / va determination, reaching tens to hundreds of corner points; second apodization / chirping provided by IDT106 | i 2|=0~10° can be set, and the extinction ratio is ≥25~35 dB (which can be further improved by using push-pull or dual units).

[0063] Optional features and types: Both the first apodization / chirped IDT104 and the second apodization / chirped IDT106 are envelope-weighted (Hanning / Chebyshev) and electrode chirped in combination to suppress sidelobes; multiple IDTs can be connected in parallel or series to extend bandwidth; electro-acoustic impedance matching and power distribution network integration; the output end can use a single-layer or double-layer grating to optimize coupling efficiency and bandwidth; the receiver end can be an on-chip coherent receiver or an external detector, both synchronized with the transmitter end.

[0064] Example 7 This embodiment is a first embodiment of a lidar system, such as... Figure 4 As shown, it includes: The light source and electro-optic modulation module 301 are used to realize the frequency modulated continuous wave (FMCW) system; it includes a laser 311 and an electro-optic modulation module 312. The chip-level acousto-optic beam controller or multi-channel chip-level acousto-optic beam controller provided in Examples 1 to 5 above; The radio frequency synthesis and control module 302 is used to apply a programmable drive for single tone, frequency sweep or multiple tone to the first apod / chirp IDT 104 and the second apod / chirp IDT 106; And a coherent receiving and signal processing module 303, used to analyze the beat frequency signal to obtain distance information, and determine the azimuth angle by the drive frequency or sub-band index, thereby realizing three-dimensional imaging.

[0065] In this embodiment, the coherent receiving and signal processing module 303 performs spectral analysis or two-dimensional Fourier transform on the beat frequency signal to obtain distance and angular dimension information, respectively.

[0066] In this embodiment, the radio frequency synthesis and control module 302 outputs multiple non-overlapping or partially overlapping RF audio signals to achieve multi-beam parallel scanning.

[0067] In this embodiment, a lidar system, based on the frequency-angle mapping of the chip-level acousto-optic beam controller, maps the driving frequency to the emission angle, uses coherent beat frequency to obtain the echo intermediate frequency signal to calculate distance information, and determines the angle information by driving frequency or sub-band index.

[0068] Example 8 This embodiment is an example of a frequency-angle resolution method, employing a chip-level acousto-optic beam controller or a multi-channel chip-level acousto-optic beam controller as described in any one of embodiments one through six. Figure 5 As shown, it includes the following steps: The first apodization / chirping IDT104 is driven by a preset single-tone, sweep, or multi-tone RF signal, which causes the output beam to deflect at an angle. i 1 and driving frequency f RF Establish a monotonic frequency-angle mapping relationship; Drive / disengage the second apodization / chirping IDT106 with a preset single-tone, sweep, or multi-tone RF signal to set or switch the additional deflection angle of the emitted light in the XY plane. i 2; The branch emitting the laser is used as the local oscillator, and coherently beats with the echo to obtain the intermediate frequency signal; The target distance is determined based on the beat frequency component of the intermediate frequency signal; Based on the frequency-angle mapping relationship, the target azimuth angle is determined using the frequency information of the intermediate frequency signal.

[0069] In this embodiment, amplitude or phase weighting is applied to the RF signal to suppress angular sidelobes, and pre-distortion compensation is performed on the diffraction efficiency at different frequencies to achieve a larger field of view.

[0070] The method provided in this embodiment can support multi-tone parallel transmission and echo separation, and realize simultaneous imaging from multiple angles.

[0071] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered to be within the scope of this specification.

[0072] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A chip-scale acousto-optic beam controller, comprising: include: Insulating substrate (101); A lithium niobate thin film layer (102) disposed on the insulating substrate (101) is used for electro-acoustic conversion; A chalcogenide glass waveguide layer (103) disposed on the lithium niobate thin film layer (102) is used to form an acousto-optic interaction region; A first apodization / chirping IDT (104) is disposed on the lithium niobate thin film layer (102) for exciting surface acoustic waves / Love waves and forming an equivalent acoustic grating in the acousto-optic region; The incident grating coupler (105) is arranged in the chalcogenide glass waveguide layer (103), and is used for making the deflection angle of the outgoing light exiting through the incident grating coupler (105) relative to the X direction in the XZ plane θ 1 with driving frequency f RF monotonically changes to establish a frequency-angle mapping; A second apodization / chirped IDT (106), disposed on the lithium niobate thin film layer (102), is arranged in the region surrounding the exit end of the incident grating coupler (105) to apply a transverse phase distribution to the outgoing wavefront in the XY plane, thereby generating a controllable additional deflection angle relative to the X direction in the XY plane. θ 2. Or sidelobe suppression.

2. The chip-level acousto-optic beam controller according to claim 1, characterized in that, Both the first apodization / chirped IDT (104) and the second apodization / chirped IDT (106) adopt a combination structure of envelope weighting and electrode periodic chirping to obtain a bandwidth of ≥10% while maintaining high diffraction efficiency and suppressing angular sidelobes; wherein, the second apodization / chirped IDT (106) adopts a focused or tilted apodization / chirped IDT.

3. The chip-level acousto-optic beam controller according to claim 2, characterized in that, The second apodization / chirping IDT (106) employs an arc-shaped, elliptical, or phase-coded structure to make the additional deflection angle θ 2. The setting is available in the range of 0~10°.

4. The chip-level acousto-optic beam controller according to claim 1, characterized in that, It also includes an acoustic absorption or isolation structure (107) disposed on the periphery of the acousto-optic interaction area to suppress acoustic reflection and channel crosstalk; it also includes an on-chip monitoring and calibration unit for acquiring the emission angle and establishing / updating f RF – θ 1. Mapping relationship to compensate for temperature and process drift.

5. A multi-channel chip-level acousto-optic beam controller, characterized in that, It includes a 1×N on-chip beam splitter (201), where N≥2, for distributing incident light to N parallel acousto-optic channels (202), each of the parallel acousto-optic channels (202) being provided with a chip-level acousto-optic beam controller as described in any one of claims 1 to 4.

6. The multi-channel chip-level acousto-optic beam controller according to claim 5, characterized in that, The parallel acousto-optic channels (202) are spliced ​​in the angular domain to expand the total field of view; or, multiple independent angles of outgoing beams are generated in the same field of view in a multi-tone parallel manner.

7. A lidar system, characterized in that, include: The light source and electro-optic modulation module (301) are used to realize the frequency modulated continuous wave (FMCW) system; The chip-level acousto-optic beam controller as described in any one of claims 1 to 6; The radio frequency synthesis and control module (302) is used to apply a single tone, a sweep frequency or a multi-tone programmable drive to the first apod / chirp IDT (104) and the second apod / chirp IDT (106); And a coherent receiving and signal processing module (303) is used to analyze the beat frequency signal to obtain distance information and determine the azimuth angle by the drive frequency or sub-band index, thereby realizing three-dimensional imaging.

8. The lidar system according to claim 7, characterized in that, The radio frequency synthesis and control module (302) outputs multiple non-overlapping or partially overlapping RF audio signals, thereby achieving multi-beam parallel scanning.

9. A frequency-angle resolution method, characterized in that, The chip-level acousto-optic beam controller according to any one of claims 1 to 6 includes the following steps: The first apodization / chirped IDT (104) is driven by a preset single-tone, sweep, or multi-tone RF signal, causing the outgoing beam to deflect at an angle... θ 1 and driving frequency f RF Establish a monotonic frequency-angle mapping relationship; The second apodization / chirped IDT (106) is driven / not driven by a preset single-tone, sweep, or multi-tone RF signal to set or switch the additional deflection angle of the emitted light in the XY plane. θ 2; The branch emitting the laser is used as the local oscillator, and coherently beats with the echo to obtain the intermediate frequency signal; The target distance is determined based on the beat frequency component of the intermediate frequency signal; Based on the frequency-angle mapping relationship, the target azimuth angle is determined using the frequency information of the intermediate frequency signal.

10. The frequency-angle resolution method according to claim 9, characterized in that, A larger field of view can be achieved by applying amplitude or phase weighting to the RF signal to suppress angular sidelobes and by pre-distorting the diffraction efficiency at different frequencies.

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