Switching optical beam scanning system and method based on acousto-optic effect

Abstract

A switching type optical beam scanning system and method based on acousto-optic effect. The system comprises a chip, an optical device and an acoustic device; the optical device comprises a laser, a 1xN optical switch, a routing waveguide and N beam expanders; the acoustic device comprises a radio frequency source, a 1xN electrical switch and N interdigital transducers. The beam expanders and the interdigital transducers are alternately arranged on a reference circular circumference and located at the ends of the same diameter, so that the optical wave and the acoustic wave propagate coaxially and oppositely. A controller switches the optical switch and the electrical switch to select different scanning unit pairs, and tunes the radio frequency to change the diffraction angle, so as to realize two-dimensional optical beam scanning without lens assistance. The present application only needs a single radio frequency source, has simple structure, convenient control and high acousto-optic interaction efficiency, and can be widely used in the fields of laser radar and free space optical communication.

Description

Technical Field

[0001] This invention relates to the field of beam scanning technology, and in particular to a switching beam scanning system and method based on the acousto-optic effect. Background Technology

[0002] Integrated beam scanning has significant application value in fields such as laser communication and beam manipulation. All-solid-state beam scanning technologies, such as optical phased arrays and focal plane switching, have been extensively studied. However, to achieve two-dimensional scanning, the former typically requires wavelength assistance, while the latter usually requires lens assistance. Acousto-optic scanning technology utilizes the piezoelectric effect of materials to generate mechanical waves, thereby achieving controllable deflection of the beam. Patent US20220206358A1 uses the acousto-optic effect to form a grating, allowing the beam's propagation direction to break away from the acousto-optic material and be emitted into free space, but requires two microwave sources to drive it for two-dimensional scanning. Patent ZL202310400026.4 (All-solid-state beam scanner based on acousto-optic effect) achieves two-dimensional scanning of the beam into free space using an on-chip acousto-optic phased array, but the control of the phased array is relatively complex. Furthermore, in both of the above patents, as the non-coaxial angle between the beam and the sound wave increases, the emission efficiency decreases.

[0003] Therefore, how to achieve efficient and wide-range two-dimensional beam scanning without increasing system complexity (such as multiple microwave sources, complex phased arrays, or auxiliary lenses) and ensure that high acousto-optic efficiency is maintained throughout the scanning process is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention provides a switching beam scanning system and method based on the acousto-optic effect. By employing on-chip paired switching between interdigital transducer (IDT) arrays and optical emitting units, the light and sound waves are always in a coaxial state, effectively improving emission efficiency, and requiring only one microwave source for driving. This solution has a simple structure, enables efficient, lens-free two-dimensional beam scanning, and has broad application prospects.

[0005] The technical solution of the present invention is as follows: A switching beam scanning system based on acousto-optic effect, comprising: The chip has an acousto-optic material thin film layer. This acousto-optic material thin film has both piezoelectric properties, enabling it to excite sound waves by applying a voltage, and optical transparency, enabling it to support low-loss propagation of light waves of specific wavelengths.

[0006] The optical and acoustic components disposed on the chip are arranged relative to each other by a virtual reference circle.

[0007] The optical components include: a laser, a 1×N optical switch, N waveguide routes, and N beam expanders, where N is a positive integer greater than or equal to 2. The specific connections and positions are as follows: The laser's output terminal is optically coupled to the 1×N optical switch's input terminal.

[0008] The N optical output terminals of the 1×N optical switch are optically coupled to one end of each of the N routing waveguides.

[0009] The other ends of the N routing waveguides are optically coupled to the optical input ends of the N beam expanders, respectively.

[0010] All N beam expanders are located on the circumference of the same virtual reference circle, and the optical output port of each beam expander points to the center of the virtual reference circle.

[0011] The acoustic device component includes: a radio frequency source, a 1×N electrical switch, and N interdigital transducers. The specific connections and positions are as follows: The electrical output terminal of the radio frequency source is electrically connected to the electrical input terminal of the 1×N electrical switch.

[0012] The N electrical output terminals of the 1×N electrical switch are respectively electrically connected to the electrical input terminals of the N interdigital transducers.

[0013] All N interdigital transducers are located on the circumference of the virtual reference circle, and the acoustic wave emission direction of each interdigital transducer is directed towards the center of the virtual reference circle.

[0014] The beam expander and the interdigital transducer are arranged alternately on the circumference of the virtual reference circle, and one interdigital transducer and one beam expander constitute a scanning unit pair. The interdigital transducer and the beam expander constituting the same scanning unit pair are located at opposite ends of the same diameter of the virtual reference circle, such that the propagation direction of the acoustic wave emitted by the interdigital transducer and the propagation direction of the light wave emitted by the beam expander are collinear and opposite in the plane of the chip.

[0015] The controller is electrically connected to the control terminal of the laser, the control terminal of the 1×N optical switch, the control terminal of the radio frequency source, and the control terminal of the 1×N electrical switch, respectively, and is used to control the light output of the laser, control the 1×N optical switch to select any output port, control the output frequency of the radio frequency source, and control the 1×N electrical switch to select any output port.

[0016] As a preferred technical solution, the acousto-optic material film is made of lithium niobate, lithium tantalate, or aluminum nitride, and the thickness of the acousto-optic material film is less than 500 nm, so as to enhance the moving boundary effect and improve the modulation depth of the acoustic wave forming grating.

[0017] As a preferred technical solution, the chip further includes a lower cladding layer and a substrate wafer located below the acousto-optic material film; the substrate wafer is made of an acoustic wave loss material, or the lower cladding layer is partially hollowed out in the acousto-optic interaction region between the interdigital transducer and the beam expander, so as to confine the acoustic wave energy within the acousto-optic material film and enhance the acousto-optic interaction efficiency.

[0018] As a preferred technical solution, the beam waist width of the output beam of the beam expander is matched with the width of the acoustic beam excited by the interdigital transducer, and both widths are greater than 100 μm, so as to increase the acousto-optic interaction area and reduce the divergence angle of the diffracted beam in free space, thereby achieving lensless collimation.

[0019] As a preferred technical solution, the electrode period of the interdigital transducer varies with chirp along the direction of sound wave propagation, enabling it to support the excitation of sound waves at radio frequency within a continuous bandwidth; the operating frequency of the interdigital transducer is in the GHz range.

[0020] As a preferred technical solution, the straight-line distance between the interdigital transducer and the beam expander constituting the same scanning unit pair is on the order of millimeters to centimeters to ensure sufficient acousto-optic interaction length.

[0021] The present invention also provides a beam scanning method based on the above system, comprising the following steps: ① The controller controls the 1×N optical switch to select the i-th output port, and simultaneously controls the 1×N electrical switch to select the i-th output port, so as to select the i-th scan unit pair, where i is any integer from 1 to N; ② The laser is activated to output a single-frequency continuous laser. The laser passes sequentially through the 1×N optical switch, the i-th route waveguide, and the i-th beam expander, and then propagates within the acousto-optic material film in a direction pointing towards the center of the virtual reference circle. ③ The radio frequency source is activated to output a frequency-adjustable radio frequency signal. The radio frequency signal is applied to the i-th interdigital transducer via the 1×N electrical switch. The i-th interdigital transducer excites a sound wave that propagates in the direction of the center of the virtual reference circle. The sound wave and the light wave in step ② are coaxial and propagate in opposite directions within the chip plane. ④ The sound wave forms a dynamic Bragg grating in the acousto-optic material film. When the light wave interacts with the dynamic Bragg grating and satisfies the Bragg phase matching condition, diffraction occurs, forming a diffracted beam emitted into free space. ⑤ By continuously adjusting the output frequency of the radio frequency source through the controller, the wavelength of the sound wave is changed, thereby changing the angle between the diffracted beam and the normal direction of the chip, and realizing the first-dimensional (pitch direction) beam scanning. ⑥ By switching the 1×N optical switch and the 1×N electrical switch to the j-th output port through the controller, the j-th scanning unit pair is selected, where j is an integer from 1 to N that is different from i, thereby changing the propagation direction of the light wave and the sound wave in the chip plane and realizing the second-dimensional (horizontal direction) beam scanning. ⑦ Repeat steps ⑤ and ⑥ to achieve lens-free two-dimensional beam scanning.

[0022] In the above method, the Bragg phase matching condition is specifically as follows: IDT-induced acoustic wave vector K for in, f It is the modulation frequency on the IDT. v It is the speed at which sound waves propagate in an acousto-optic thin film. K The direction is the emission direction of the IDT. The wave vector of the light wave emitted by the beam expander. k 1 is in, n eff It is the effective refractive index of light. f opt It is the frequency of light. c It is the speed of light in a vacuum. k 0 = 2 πf opt / c It is the wave vector of light in a vacuum. k The direction of 1 is the direction of the light wave emitted by the beam expander, which is opposite to the sound wave. Therefore, the angle between the beam diffracted into free space and the chip plane is... θ (Taking first-order diffraction as an example) The optical frequency should be selected appropriately. f opt and radio frequency f This makes the above equation true, meaning the absolute value of the term on the right side of the equation is less than 1. At this point, if the frequency of the radio frequency source is changed by the controller... f The frequency of the acoustic wave excited by the IDT also changes accordingly. According to the phase matching condition mentioned above, the light wave will be diffracted to different angles in free space, achieving beam scanning perpendicular to the chip direction. If the optical and electrical signals are switched to another pair of beam expanders and IDTs, beam scanning horizontally to the chip direction can be achieved.

[0023] Preferably, the frequency of the light wave output by the laser and the frequency of the radio frequency output by the radio frequency source satisfy the Bragg phase matching condition, so that the light wave energy is concentrated in the first diffraction order in free space, thereby improving the emission efficiency.

[0024] Preferably, in step ⑤, continuous scanning of the diffraction angle is achieved by continuously tuning the frequency of the radio frequency source; in step ⑥, discrete angle step scanning in the horizontal direction is achieved by sequentially switching different scanning unit pairs, and the scanning step size in the horizontal direction is determined by the central angle spacing between adjacent beam expanders on the virtual reference circle.

[0025] Compared with the prior art, the present invention has the following advantages: 1) This invention employs a switching approach, pairing the IDT with the beam expander to ensure that the acoustic and optical waves emitted by both remain collinear and propagate in opposite directions, maximizing acousto-optic diffraction efficiency. Simultaneously, since the optical wave has a large mode spot on the plate, its beam divergence angle after diffracting into free space is also small, eliminating the need for additional lens collimation and enabling lensless single-wavelength two-dimensional beam scanning.

[0026] 2) Compared with similar solutions based on acousto-optic effects, such as patents US20220206358A1 and ZL202310400026.4, this invention avoids the defects of reduced effective area and reduced diffraction efficiency caused by non-collinear propagation of sound waves and light waves, and adopts a single radio frequency source design, which is simple to control. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the switching beam scanning system based on the acousto-optic effect of the present invention.

[0028] In the diagram: 1-Chip, 2-Reference circle, 3-Laser, 4-1×N optical switch, 5-Route waveguide, 6-Beam expander, 7-RF source, 8-1×N electrical switch, 9-Interdigital transducer, 10-Controller.

[0029] Figure 2 This is a schematic diagram illustrating the principle of wave vector synthesis of light waves and sound waves in this invention.

[0030] In the picture, K It is the acoustic wave vector, with the direction of the interdigitated transducer's emission direction, pointing towards the center of the circle along the chip plane; k 1 is the wave vector of the guided light wave on the chip, with the direction of the beam expander emission direction, pointing towards the center of the circle along the chip plane, opposite to the direction of the sound wave; k 0 is the wave vector of the beam diffracted into free space. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the scope of protection of the present invention. Embodiments of the present invention include, but are not limited to, the following embodiments.

[0032] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a switching beam scanning system based on acousto-optic effect provided in Embodiment 1 of the present invention.

[0033] This embodiment provides a switching beam scanning system based on the acousto-optic effect, the specific structure of which is as follows: Chip 1 employs a lithium niobate on insulator (LNOI) platform. From top to bottom, chip 1 consists of an acousto-optic material thin film, a lower cladding layer, and a substrate wafer. The acousto-optic material thin film is a material with piezo-acoustic effects; when a voltage is applied to its surface, it can excite sound waves of a corresponding frequency. The acousto-optic material thin film is also a light-transmitting material, allowing light of specific wavelengths to propagate within it with low loss. In this embodiment, the acousto-optic material thin film is lithium niobate, lithium tantalate, aluminum nitride, or other acousto-optic materials. Its thickness is less than 500 nm to enhance the moving boundary effect, resulting in a higher refractive index modulation depth (i.e., refractive index contrast) for light waves propagating in the thin film. The substrate material should ensure that sound waves do not easily propagate, or the lower cladding layer beneath the acousto-optic material thin film can be hollowed out using a wet process, allowing sound waves to be confined within the acousto-optic material thin film and enhancing the efficiency of acousto-optic interaction. In this embodiment, the material is high-resistivity silicon (Si) with a thickness of 500 μm. Silicon substrates exhibit high absorption and scattering losses for acoustic waves, effectively suppressing acoustic wave leakage into the substrate. To further enhance acoustic wave confinement, this embodiment can also employ a wet etching process to partially hollow out the silicon dioxide lower cladding layer located between the interdigital transducer 9 and the beam expander 6, forming an air isolation groove. This ensures that the acoustic wave energy is completely confined within the lithium niobate film, thereby maximizing the acousto-optic interaction efficiency.

[0034] Reference circle 2 is a virtual geometric reference circle, the center of which is located in the central region of chip 1. Reference circle 2 is used to define the relative positional relationship between optical and acoustic devices. N pairs of devices are distributed at equal angles on its circumference, that is, optical and acoustic devices are located on both sides of the diagonal of the circumference. In this embodiment, N is 8.

[0035] The optical components, arranged sequentially along the direction of optical signal propagation, include: a laser 3, a 1×N optical switch 4, a routing waveguide 5, and a beam expander 6. The laser 3 is externally coupled to the input port of the 1×N optical switch 4 via end-face coupling. In another variant embodiment, the laser 3 can also be integrated onto the chip 1 via heterogeneous bonding. The 1×N optical switch 4, the routing waveguide 5, and the beam expander 6 are fabricated on an acousto-optic material thin film of the chip 1. The N output ports of the 1×N optical switch 4 are connected to the N beam expanders 6 via the N routing waveguides 5. The N beam expanders 6 are arranged at equal angular intervals on one side of the circumference of the reference circle 2, with the optical output port of each beam expander pointing towards the center of the reference circle 2.

[0036] The acoustic device, along the direction of electrical signal propagation, includes, in sequence: a radio frequency (RF) source 7, a 1×N electrical switch 8, and an interdigital transducer (IDT) 9. The IDTs are fabricated on top of the acousto-optic material film of chip 1. The N output ports of the 1×N electrical switch 8 are connected to the N IDTs via wire bonding. The IDTs are arranged on the outer periphery of the reference circle, opposite the beam expander. The direction of sound wave emission from the IDTs points towards the center of the reference circle, and each IDT corresponds to one beam expander, located at opposite ends of the diagonal of the circle. The IDT 9 has a chirped period, supporting RF frequency excitation of sound waves within a certain bandwidth. The RF source 7 is a frequency-tunable RF signal source, and its frequency tuning range matches the frequency range excitation range of the IDT 9. The laser frequency output from laser 3 and the modulation frequency applied to IDT 9 should match each other, ensuring that the wave vectors of the light and sound waves on the chip satisfy the phase matching condition, allowing diffraction of a beam emitted into free space. Preferably, the beamwidth of the acoustic wave generated by the IDT excitation and the beamwidth of the beam output by the beam expander should match and be greater than 100 μm to increase the acousto-optic interaction area and improve the divergence angle after beam emission. The frequency range that the IDT can excite is in the GHz range. The distance from the IDT to the beam expander on its diagonal is in the millimeter to centimeter range.

[0037] The controller 10 is connected to the laser 3, the 1×N optical switch 4, the radio frequency source 7, and the 1×N electrical switch 8 via leads on a printed circuit board (PCB). The controller 10 is responsible for the following tasks: Control the switching state of 1×N optical switches 4 to select the i-th output port; Control the switching state of 1×N electrical switches 8 and select the i-th output port; Control the output frequency and power of RF source 7; Control whether the laser 3 emits light and its power.

[0038] The specific steps for implementing two-dimensional beam scanning in this embodiment are as follows: Step ①: Select scanning unit pair Suppose we need to scan the beam to the horizontal angle φ = 0° (i.e.) Figure 1 (The middle finger points to the right). Controller 10 controls 1×N optical switch 4 to select the i-th output port (i corresponds to the horizontal right beam expander 6), and simultaneously controls 1×N electrical switch 8 to select the i-th output port (i corresponds to the horizontal left interdigital transducer 9). This selects the i-th scanning unit pair: the left IDT and the right beam expander.

[0039] Step 2: Light wave emission Controller 10 activates laser 3, outputting a single-frequency continuous laser with a wavelength of 1550 nm. The laser sequentially passes through a 1×N optical switch 4, the i-th route waveguide 5, and the i-th beam expander 6. After beam expander 6 enlarges the mode spot to approximately 110 μm, it emits a light wave within the acousto-optic material film in a direction pointing towards the center of reference circle 2. The propagation direction of this light wave within the plane of chip 1 is from right to left (pointing towards the center).

[0040] Step 3: Sound wave excitation Controller 10 activates RF source 7, outputting an adjustable RF signal with frequency f. This signal is applied to the i-th interdigital transducer 9 (the IDT on the horizontal left) via a 1×N electrical switch 8. This IDT excites sound waves, which also propagate in the direction pointing towards the center of the reference circle 2, i.e., propagating from left to right (pointing towards the center) within the plane of chip 1. Thus, the sound wave and the light wave propagate coaxially and in opposite directions within the plane of chip 1, and the interaction length is the distance between the IDT and the beam expander (approximately 4.5 mm), achieving the theoretically maximized acousto-optic interaction length.

[0041] Step 4: Acousto-optic diffraction When sound waves propagate in an acousto-optic thin film, the refractive index of the material changes periodically due to the elasto-optic effect, forming a dynamic Bragg grating. When light waves pass through this grating, the light wave components that satisfy the Bragg phase-matching condition undergo diffraction and are diffracted out into free space.

[0042] Please see Figure 2 The diagram shows a schematic of wave vector synthesis. In the diagram, K is the acoustic wave vector, pointing towards the center of the circle along the chip plane, with a magnitude of K = 2πf / v, where f is the radio frequency and v is the propagation speed of sound in lithium niobate (approximately 3440 m / s). k1 is the wave vector of the guided optical wave on the chip, pointing towards the center of the circle along the chip plane (opposite to K), with a magnitude of k1 = 2πn. eff / λ, where n eff λ is the effective refractive index of the guided wave mode. k0 is the wave vector of the beam diffracted into free space, with a magnitude of k0 = 2π / λ, and the angle θ between its direction and the chip normal is the diffraction angle.

[0043] The direction of light wave diffracted by sound wave satisfies the phase-matching condition: the sound wave vector excited by IDT K for in, f It is the modulation frequency on the IDT. v It is the speed at which sound waves propagate in an acousto-optic thin film. K The direction is the emission direction of the IDT. The wave vector of the light wave emitted by the beam expander. k 1 is in, n eff It is the effective refractive index of light. f opt It is the frequency of light. c It is the speed of light in a vacuum. k 0 = 2 πf opt / c It is the wave vector of light in a vacuum. k The direction of 1 is the direction of the light wave emitted by the beam expander, which is opposite to the sound wave. Therefore, the angle between the beam diffracted into free space and the chip plane is... θ (Taking first-order diffraction as an example) The optical frequency should be selected appropriately. f opt and radio frequency f This makes the above equation true, meaning the absolute value of the term on the right side of the equation is less than 1. At this point, if the frequency of the radio frequency source is changed by the controller... f The frequency of the acoustic wave excited by the IDT also changes accordingly. According to the phase matching condition mentioned above, the light wave will be diffracted to different angles in free space, achieving beam scanning perpendicular to the chip direction. If the optical and electrical signals are switched to another pair of beam expanders and IDTs, beam scanning horizontally to the chip direction can be achieved.

[0044] This embodiment details a switching beam scanning system and its scanning method based on the acousto-optic effect. By pairing interdigital transducers and beam expanders at both ends of the same diameter of a virtual reference circle, sound waves and light waves propagate coaxially and in opposite directions, maximizing the efficiency of acousto-optic interaction. A single-channel RF source combined with switching enables extremely simple two-dimensional scanning control; and a large-spot beam expander achieves lens-free collimation. This solution effectively overcomes the shortcomings of existing technologies, such as low efficiency, complex control, and the need for auxiliary lenses, and has significant innovative and industrial practical value.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the spirit and principle of the present invention, such as changing the specific value of N, replacing the acousto-optic material, adjusting the IDT period parameters, etc. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A switching beam scanning system based on acousto-optic effect, characterized in that, include: Chip (1), said chip (1) having an acoustic light material thin film layer; Optical and acoustic components are disposed on the chip (1); The optical components include: a laser (3), a 1×N optical switch (4), N routing waveguides (5), and N beam expanders (6), where N is a positive integer greater than or equal to 2; the optical output end of the laser (3) is optically coupled to the optical input end of the 1×N optical switch (4); the N optical output ends of the 1×N optical switch (4) are optically coupled to one end of each of the N routing waveguides (5); the other ends of the N routing waveguides (5) are optically coupled to the optical input ends of each of the N beam expanders (6); the N beam expanders (6) are all located on the circumference of the same virtual reference circle (2), and the optical output port of each beam expander (6) points to the center of the virtual reference circle (2); The acoustic device includes: a radio frequency source (7), a 1×N electrical switch (8), and N interdigital transducers (9); the electrical output terminal of the radio frequency source (7) is electrically connected to the electrical input terminal of the 1×N electrical switch (8); the N electrical output terminals of the 1×N electrical switch (8) are respectively electrically connected to the electrical input terminals of the N interdigital transducers (9); the N interdigital transducers (9) are all located on the circumference of the virtual reference circle (2), and the sound wave emission direction of each interdigital transducer (9) points to the center of the virtual reference circle (2); The beam expander (6) and the interdigital transducer (9) are arranged alternately on the circumference of the virtual reference circle (2), and one interdigital transducer (9) and one beam expander (6) constitute a scanning unit pair. The interdigital transducer (9) and the beam expander (6) constituting the same scanning unit pair are located at opposite ends of the same diameter of the virtual reference circle (2), such that the propagation direction of the sound wave emitted by the interdigital transducer (9) is similar to the propagation direction of the light wave emitted by the beam expander (6). The chips (1) are collinear and facing each other in the plane; the controller (10) is electrically connected to the control terminal of the laser (3), the control terminal of the 1×N optical switch (4), the control terminal of the radio frequency source (7) and the control terminal of the 1×N electrical switch (8), respectively, and is used to control the light output of the laser (3), control the 1×N optical switch (4) to select any output port, control the output frequency of the radio frequency source (7) and control the 1×N electrical switch (8) to select any output port.

2. The acousto-optic switching beam scanning system according to claim 1, characterized in that, The acousto-optic material film is made of lithium niobate, lithium tantalate, or aluminum nitride, and the thickness of the acousto-optic material film is less than 500 nm.

3. The acousto-optic switching beam scanning system according to claim 1, characterized in that, The chip (1) also includes a lower cladding layer and a substrate wafer located below the acousto-optic material film; the substrate wafer is made of an acoustic wave loss material, or the lower cladding layer is partially hollowed out in the acousto-optic interaction region between the interdigital transducer (9) and the beam expander (6) to confine the acoustic wave energy within the acousto-optic material film.

4. The acousto-optic switching beam scanning system according to claim 1, characterized in that, The beam waist width of the output beam of the beam expander (6) matches the width of the acoustic beam excited by the interdigital transducer (9), and both widths are greater than 100 μm.

5. The acousto-optic switching beam scanning system according to claim 1, characterized in that, The electrode period of the interdigital transducer (9) varies with the direction of sound wave propagation, enabling it to support the excitation of sound waves at radio frequency within a continuous bandwidth; the operating frequency of the interdigital transducer (9) is in the GHz range.

6. The acousto-optic switching beam scanning system according to claim 1, characterized in that, The linear distance between the interdigital transducer (9) and the beam expander (6) that constitute the same scanning unit pair is on the order of millimeters to centimeters.

7. A beam scanning method based on the acousto-optic effect-based switching beam scanning system according to any one of claims 1 to 6, characterized in that, Includes the following steps: ① The controller (10) controls the 1×N optical switch (4) to select the i-th output port, and simultaneously controls the 1×N electrical switch (8) to select the i-th output port, so as to select the i-th scan unit pair, where i is any integer from 1 to N; ② The laser (3) is activated to output a single-frequency continuous laser. The laser passes through the 1×N optical switch (4), the i-th route waveguide (5) and the i-th beam expander (6) in sequence, and then propagates in the acousto-optic material film in a direction pointing to the center of the virtual reference circle (2). ③ The radio frequency source (7) is activated to output a radio frequency signal with adjustable frequency. The radio frequency signal is applied to the i-th interdigital transducer (9) via the 1×N electrical switch (8). The i-th interdigital transducer (9) excites a sound wave that propagates in the direction of the center of the virtual reference circle (2). The sound wave and the light wave in step ② are coaxial and propagate in opposite directions in the plane of the chip (1). ④ The sound wave forms a dynamic Bragg grating in the acousto-optic material film. When the light wave interacts with the dynamic Bragg grating and satisfies the Bragg phase matching condition, diffraction occurs, forming a diffracted beam emitted into free space. ⑤ By continuously adjusting the output frequency of the radio frequency source (7) through the controller (10), the wavelength of the sound wave is changed, thereby changing the angle between the diffracted beam and the normal direction of the chip (1) to achieve first-dimensional beam scanning; ⑥ Switch the 1×N optical switch (4) and the 1×N electrical switch (8) to the j-th output port through the controller (10) to select the j-th scanning unit pair, where j is an integer from 1 to N that is different from i, and change the propagation direction of the light wave and the sound wave in the plane of the chip (1) to realize the second-dimensional beam scanning; ⑦ Repeat steps ⑤ and ⑥ to realize lens-free two-dimensional beam scanning.

8. The beam scanning method according to claim 7, characterized in that, The Bragg phase matching condition in step ④ is as follows: the acoustic wave vector K excited by the interdigital transducer (9), the guided wave vector k1 emitted by the beam expander (6), and the wave vector k0 of the diffracted beam in free space satisfy the vector relationship k0 = k1 + K; where the direction of K is along the plane of the chip (1) pointing to the center of the circle, the direction of k1 is along the plane of the chip (1) pointing to the center of the circle and opposite to the direction of K, and the angle θ between the direction of k0 and the normal of the chip (1) is the diffraction angle: In the formula, , f It is the modulation frequency on the interdigital transducer (9). v It is the propagation speed of sound waves in acousto-optic material thin films; , n eff It is the effective refractive index of light. f opt It is the frequency of light. c It is the speed of light in a vacuum. k 0 = 2 πf opt / c It is the wave vector of light in a vacuum.

9. The beam scanning method according to claim 7, characterized in that, The light wave frequency output by the laser (3) and the radio frequency output by the radio frequency source (7) satisfy the Bragg phase matching condition, so that the light wave energy is concentrated in the first diffraction order in free space.

10. The beam scanning method according to claim 7, characterized in that, In step ⑤, continuous scanning of the diffraction angle is achieved by continuously tuning the frequency of the radio frequency source (7); in step ⑥, discrete angle step scanning in the horizontal direction is achieved by sequentially switching different scanning unit pairs, and the scanning step size in the horizontal direction is determined by the central angle spacing between adjacent beam expanders (6) on the virtual reference circle (2).

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