Annular array silicon-based optical phased array chip applicable to high power and optimization method

Abstract

The invention discloses an annular array silicon-based optical phased array chip applicable to high power and an optimization method. In the invention, a coupling grating module is used for receiving an incident light beam, a cascade light splitting module is used for splitting the incident light beam into multiple paths of unmodulated detection light beams, and a phase modulation module is used for carrying out phase modulation on each path of unmodulated light beam to generate a phase-modulated detection light beam; the two-dimensional antenna ring array module is used for transmitting all phase-modulated detection light beams to the outside of the chip, and the high-power broadened waveguide is used as a light beam transmission channel; the two-dimensional antenna annular array module is of an axial symmetry structure and is mainly formed by arranging at least one concentric two-dimensional antenna annular array at intervals in the radial direction from inside to outside, and each two-dimensional antenna annular array is mainly composed of a plurality of two-dimensional grating antennas evenly arranged along the circumference. The chip provided by the invention has high continuous wave optical power bearing capacity, low nonlinear loss and heat accumulation.

Description

Technical Field

[0001] The present invention relates to an integrated optical device, and particularly to a silicon-based optical phased array chip suitable for high-power continuous light input. Background Art

[0002] Due to its high integration and controllability, optical phased array has become one of the important directions in the development of lidar technology. However, existing silicon-based optical phased array (OPA) chips have problems with insufficient power-carrying capacity in applications. Especially in the scenario of continuous-wave high-power input, the nonlinear loss and thermal effect of the waveguide increase significantly, resulting in a decrease in the signal-to-noise ratio of distant targets, thus seriously affecting the detection performance.

[0003] On the one hand, the current silicon-based optical phased array chips are based on a 220-nm-thick silicon layer, and the corresponding waveguide mode field area is limited. Obvious nonlinear effect losses and thermal effects occur under high-power conditions. The broadened waveguide based on this platform will further limit the device integration. In the scenario of high-power continuous-wave applications, the power transmission performance is significantly restricted. The cross-sectional area of silicon-based optical waveguides is usually in the order of hundreds of nanometers to micrometers. The internal optical power density far exceeds that of other optical devices and is the lowest power threshold unit in the high-power continuous-wave application of optical phased arrays. The high power density leads to a significant increase in the intrinsic absorption and nonlinear absorption of the material. At the same time, the increase in carrier density causes a sudden rise in the local temperature. Given that the optical phased array relies on the precise phase control of multiple waveguides, once any channel is burned out, it will cause the overall wavefront distortion. The optical phased array for high-power applications needs to carry continuous-wave light input in the infrared band with a power of the order of watts, and this significant performance requirement has exceeded the power transmission limit of traditional single-mode waveguides. To address this problem, increasing the mode area on the traditional 220-nm-thick silicon layer or introducing a silicon layer on the micron scale can effectively improve the power-carrying capacity and stability of the device to a certain extent. However, these methods will simultaneously bring problems such as a significant increase in the size of the device structure and deterioration of waveguide performance.

[0004] On the other hand, most of the existing radiation antenna array designs adopt uniform or sparse arrangement methods. The limitation of the antenna spacing leads to problems such as heat accumulation, accompanied by strong losses and beam quality degradation in high-power array continuous wave application scenarios. For example, the traditional periodic array element arrangement method with equal spacing, equal amplitude and phase, and equal number of rings will result in higher sidelobe energy in the far-field pattern, reducing the focusing efficiency of the main lobe; at the same time, problems such as heat accumulation formed by the thermal field superposition of adjacent array elements under continuous wave high-power applications are not considered. Therefore, it is limited by characteristics such as high sidelobes, poor thermal management, structural solidification, manufacturing sensitivity, and insufficient dynamic capabilities. In addition, in the traditional periodic array with equal spacing, the arrangement spacing of the rectangular antenna array units is the same. Although it has good symmetry and simple mathematical description, with the increase of the array scale, in high-power applications, there are still two main problems: one is that the array elements are evenly distributed in physical space, and more units need to be connected in the central area of the array, making these waveguide paths complex, which in turn leads to crosstalk between waveguides and affects the beam quality; the other is that in a highly integrated array, the dense complexity of the waveguides in the central area will also bring corresponding heat accumulation problems.

[0005] In summary, the above-mentioned many factors jointly restrict the application of optical phased array chips in long-distance and high-precision lidar systems. Existing silicon-based optical phased array chips still face the problem of significantly increased nonlinear losses and thermal effects of waveguides in the continuous wave high-power optical input scenario, which will further lead to a decrease in the signal-to-noise ratio of distant targets, thus seriously affecting the detection performance, and cannot simultaneously meet the requirements for waveguide transmission capacity, heat management, high beam quality, and integration under the condition of watt-level high-power input. Summary of the Invention

[0006] Aiming at the problems of insufficient power-carrying capacity, high nonlinear losses, and heat accumulation in existing silicon-based optical phased array chips, the present invention provides a high-power applicable annular array silicon-based optical phased array chip and an optimization method. The silicon-based optical phased array chip of the present invention has a high continuous optical power input carrying capacity, can not only achieve two-dimensional scanning under the condition of watt-level high-power input, but also has advantages such as a high sidelobe suppression ratio and high integration. In addition, the optimization method of the present invention can further improve the uniformity of the thermal distribution of the silicon-based optical phased array chip and improve the heat management performance.

[0007] The technical solutions adopted by the present invention are as follows: I. A high-power applicable annular array silicon-based optical phased array chip The annular array silicon-based optical phased array chip includes a coupling grating module, a cascaded beam splitting module, a phase modulation module, a two-dimensional antenna annular array module, and a high-power broadening waveguide. The coupling grating module is used to receive the incident light beam. The cascaded beam splitting module is used to split the incident light beam into multiple unmodulated detection light beams. The phase modulation module is used to perform phase modulation on each unmodulated light beam to generate a phase-modulated detection light beam. The two-dimensional antenna annular array module is used to emit all the phase-modulated detection light beams upward outside the chip to achieve two-dimensional beam scanning. The high-power broadening waveguide is used as the optical channel on the annular array silicon-based optical phased array chip, that is, the light beam transmission channel. The two-dimensional antenna annular array module adopts an axisymmetric structure and is mainly composed of at least one concentric two-dimensional antenna annular array arranged at intervals from the inside to the outside along the radial direction. Each two-dimensional antenna annular array is mainly composed of multiple two-dimensional grating antennas arranged uniformly along the circumference.

[0008] Specifically, the cascaded beam splitting module includes a first-stage beam splitter and two beam splitting cascaded networks, which are respectively arranged on both sides of the two-dimensional antenna annular array module and are symmetrically arranged with respect to the symmetry axis of the two-dimensional antenna annular array module. The input end of the first-stage beam splitter is connected to the output end of the coupling grating module through a high-power broadening waveguide. The two output ends of the first-stage beam splitter are respectively connected to the input ends of the two beam splitting cascaded networks through high-power broadening waveguides. The output end of each beam splitting cascaded network is connected to the two-dimensional antenna annular array module on the same side through a high-power broadening waveguide.

[0009] Specifically, the phase modulation module includes two phase shifter arrays, which are respectively arranged above the output ends of the two beam splitting cascaded networks.

[0010] Specifically, the output end of each beam splitting cascaded network includes N branch output waveguides, each phase shifter array includes N phase shifters, and the two-dimensional antenna annular array module includes 2N two-dimensional grating antennas, that is, N two-dimensional grating antennas are arranged on both sides of the symmetry axis of the two-dimensional antenna annular array module.

[0011] Specifically, for the beam splitting cascaded network, the phase shifter array, and the two-dimensional antenna annular array module on the same side of the symmetry axis of the two-dimensional antenna annular array module, the number of branch output waveguides, phase shifters, and two-dimensional grating antennas is the same and they correspond one by one. One phase shifter is arranged corresponding and aligned above each branch output waveguide. The output end of each branch output waveguide is connected to the input end of the corresponding two-dimensional grating antenna through a high-power broadening waveguide in the Manhattan routing form.

[0012] Specifically, the two-dimensional grating antenna mainly consists of three L-shaped grating structures and two grating structure gaps; the horizontal projection shapes of the L-shaped grating structures and the grating structure gaps are both arc-shaped, the vertical projection shape of the L-shaped grating structure is L-shaped, the three L-shaped grating structures are arranged radially in sequence within the same fan-shaped area on the horizontal plane, and two adjacent L-shaped grating structures are connected by a grating structure gap; the innermost L-shaped grating structure serves as the input end of the two-dimensional grating antenna and is connected to one end of the high-power broadening waveguide through a transition waveguide, and the other end of the high-power broadening waveguide is connected to the output end of the corresponding branch output waveguide. The horizontal projection shape of the transition waveguide is a truncated fan shape, the arc side of the transition waveguide is connected to the L-shaped grating structure, and the opposite side of the arc side is connected to the high-power broadening waveguide; for two two-dimensional grating antennas that are symmetric in the same two-dimensional antenna circular array, the center line connecting the centers of the corresponding fan-shaped areas of the two two-dimensional grating antennas is perpendicular to the symmetry axis of the two-dimensional antenna circular array module, thereby forming an axisymmetric structure.

[0013] Specifically, the circular array silicon-based optical phased array chip mainly consists of a silicon substrate layer, a buried layer, a thick silicon layer, a cladding layer, and a phase modulation layer that are stacked in sequence from bottom to top; the top surface of the thick silicon layer is formed with the coupling grating module, the cascaded beam splitter module, the two-dimensional antenna circular array module, and the high-power broadening waveguide through etching treatment. The high-power broadening waveguide is formed through full etching treatment, and the waveguide width of the high-power broadening waveguide remains fixed and is selected from 800 nm to 1300 nm. This high-power broadening waveguide has a higher power transmission upper limit compared to a single-mode waveguide and effectively avoids an increase in device size and deterioration of chip integration. The phase modulation layer includes a phase modulation module deposited on the top surface of the cladding layer. In the phase modulation module, each phase shifter is deposited on the top surface of the cladding layer above the corresponding branch output waveguide. The incident light beam includes continuous light in the infrared band with a power reaching the watt level.

[0014] Preferably, the beam splitting cascaded network is mainly composed of multiple levels of Y-branch beam splitters or 3 dB multimode interference couplers in cascade, and the number of cascades is adapted to the number of two-dimensional grating antennas in the two-dimensional antenna circular array module, that is, the number of two-dimensional grating antennas on one side of the symmetry axis of the two-dimensional antenna circular array module is the same as the number of branch output waveguides of the beam splitting cascaded network on the same side.

[0015] Preferably, the bending part of the optical channel on the circular array silicon-based optical phased array chip adopts an Euler bending waveguide, and the equivalent bending radius in the implementation scheme of the present invention is 12 μm, providing a compact integration of the overall array device; the Euler bending waveguide is formed on the top surface of the thick silicon layer through etching treatment.

[0016] Preferably, the phase shifter adopts a silicon-based thermo-optic phase shifter and is formed above the cladding layer through metal evaporation treatment.

[0017] Preferably, the coupling grating module adopts a two-dimensional annular coupling grating; the coupling grating module is formed on the top surface of the thick silicon layer through etching treatment.

[0018] Preferably, each two-dimensional antenna annular array includes the same number of two-dimensional grating antennas.

[0019] Furthermore, the number of the two-dimensional antenna annular arrays, the radial spacing between rings, and the element spacing of each two-dimensional antenna annular array can be optimized by a genetic algorithm according to the far-field beam sidelobe suppression ratio and the thermal distribution uniformity.

[0020] Among them, the radial spacing between rings refers to the radial spacing between two adjacent two-dimensional antenna annular arrays.

[0021] Among them, the element spacing refers to the spacing between two adjacent two-dimensional grating antennas in the two-dimensional antenna annular array.

[0022] The wavelength of the incident light beam is 1550 nm, the thickness of the thick silicon layer is 500 nm, the etching depth of the high-power broadening waveguide is 500 nm, the width of the high-power broadening waveguide is 800 nm, the etching depth of the grating structure gap is 500 nm, and the etching depth of the L-shaped grating structure is 130 nm; N is 32, the number of the two-dimensional antenna annular arrays is two, the two-dimensional grating antennas in the two two-dimensional antenna annular arrays are the same, the outer ring aperture is 720 μm, and the inner ring aperture is 500 μm.

[0023] II. An optimization method for the above-mentioned annular array silicon-based optical phased array chip The optimization method includes the following steps: using a genetic algorithm, establishing a fitness function according to the far-field beam sidelobe suppression ratio and the thermal distribution uniformity, each individual includes the number of two-dimensional antenna annular arrays, the radial spacing between rings, and the element spacing of each two-dimensional antenna annular array, after multiple generations of selection, crossover, and mutation operations, after meeting the termination conditions, the optimal individual is obtained, and the annular array silicon-based optical phased array chip is manufactured and obtained according to the number of two-dimensional antenna annular arrays, the radial spacing between rings, and the element spacing of each two-dimensional antenna annular array in the optimal individual.

[0024] Preferably, the fitness function is set according to the following formula: f = SLSR - αp1 - βp2 - γp3 In the formula, f represents the fitness, SLSR represents the far-field beam sidelobe suppression ratio, p1 represents the penalty amount of the outer ring aperture, p2 represents the penalty amount of the element spacing, p3 represents the penalty amount of the radial spacing between rings, α represents the first weight coefficient, β represents the second weight coefficient, and γ represents the third weight coefficient.

[0025] Preferably, the ranges of the three weight coefficients are 5 to 10, 2 to 5, and 1 to 3 respectively.

[0026] Preferably, the three penalty amounts are set according to the following formulas: p1 = max[0, ∑(A m - A max ) / A max p2 = max[0, (d min - d e ) / d min p3 = max[0, (1.2A m - A m+1 ) / A m In the formula, max[ ] represents the maximum value function, A m represents the aperture of the m-th ring, A max represents the maximum outer ring aperture limit, d e represents the minimum element spacing limit, d min represents the minimum spacing between any two elements.

[0027] Preferably, the far-field beam sidelobe suppression ratio is obtained through the following process: obtain the radiation pattern according to the array factor and the far-field distribution of a single antenna, and extract the far-field beam sidelobe suppression ratio from the radiation pattern according to the following formula: SLSR = 10log 10 (I main / I side ) In the formula, I main represents the main lobe peak power, I side represents the maximum sidelobe peak power.

[0028] Preferably, when the main beam points to the direction of (u0, v0), the array factor F(u, v, u0, v0) is expressed by the following formula: F(u, v, u0, v0) = ∑ M m=1 ∑ Nm N=1 E m,n e^[jkr m ((cosφ m,n (u - u0) + sinφ m,n (v - v0)] In the formula, (u0, v0) represents the main lobe direction after phase calibration, (u, v) represents the main lobe direction before phase calibration; E m,n represents the electric field strength of the n-th two-dimensional grating antenna in the m-th ring, M represents the number of two-dimensional antenna circular arrays, N m ​​​represents the total number of two-dimensional grating antennas in the m-th ring, j represents the imaginary unit, k represents the free-space wave number, and r m represents the radius of the m-th ring, that is, the distance from the center of the array to the m-th ring; φ m,n represents the azimuth angle of the n-th two-dimensional grating antenna in the m-th ring.

[0029] Among them, the free-space wave number k is obtained through the following formula: k = 2π / λ In the formula, λ represents the wavelength of the incident light beam.

[0030] The two direction cosine parameters in the main lobe direction are respectively obtained through the following formulas: u = sinφcosθ v = sinθcosφ In the formula, φ represents the azimuth angle of the main lobe direction, and θ represents the elevation angle of the main lobe direction.

[0031] Furthermore, the optimization method further includes the following steps: In each phase shifter array, the phase shifters are arranged at equal intervals along the symmetry axis direction. The spacing between adjacent phase shifters is obtained through a simulation method. The total width of the phase shifter array in the symmetry axis direction is calculated based on the number and spacing of the phase shifters, and the maximum outer ring aperture limit is set according to the total width of the phase shifter array in the symmetry axis direction.

[0032] The beneficial effects of the present invention are as follows: 1. The annular array silicon-based optical phased array chip provided by the present invention has the advantages of lower non-linear loss, higher power carrying capacity, higher signal quality, and more uniform heat distribution, etc., and can meet the requirements for waveguide transmission capacity, heat management, high beam quality, and integration degree under high-power input of the order of watts.

[0033] 2. In the annular array silicon-based optical phased array chip provided by the present invention, the broadband waveguide can stably transmit a continuous light input power of more than 1.1W.

[0034] 3. In the annular array silicon-based optical phased array chip provided by the present invention, by combining the high-power broadband waveguide and the annular array structure, the side lobe level is reduced and the heat distribution is controlled simultaneously through the optimization method, improving the comprehensive performance of the chip in high-power scenarios.

[0035] In summary, the present invention proposes an optical phased array chip structure applicable to high power and its optimization method, which has broad application prospects in the fields of integrated optics and lidar for long-distance, high-power, and high-precision applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of the annular array silicon-based optical phased array chip provided by Embodiment 1 of the present invention; In the figure: 1. Coupling grating module; 2. Cascade beam splitting module; 3. Phase modulation module; 4. Two-dimensional antenna ring array module; 5. Euler bent waveguide; 6. High-power broadening waveguide; Figure 2 It is a schematic structural diagram of a phase shifter in a ring array silicon-based optical phased array chip provided in Embodiment 1 of the present invention; Figure 3 It is a schematic diagram of a ring two-dimensional antenna array module in a ring array silicon-based optical phased array chip provided in Embodiment 1 of the present invention; Figure 4 It is a schematic diagram of a two-dimensional radiation antenna in the two-dimensional antenna ring array module provided in Embodiment 1 of the present invention; In the figure: 41. Two-dimensional grating antenna, 411. Grating structure gap, 412. L-shaped grating structure; Figure 5 It is a schematic layout diagram of a two-dimensional radiation antenna optimized by using a genetic algorithm in Embodiment 1 of the present invention; In the figure: 42. Double-ring two-dimensional antenna ring array module, 421. Outer ring antenna array, 422. Inner ring antenna array; Figure 6 It is the far-field simulation result of the double-ring two-dimensional antenna ring array module optimized by using a genetic algorithm in Embodiment 1 of the present invention; Figure 7 It is a power transmission curve graph of a broadening waveguide compared with a single-mode waveguide in Embodiment 2 of the present invention; Figure 8 It is a total insertion loss curve graph of a broadening waveguide compared with a single-mode waveguide in Embodiment 2 of the present invention. Detailed implementation manners

[0037] The following will make a detailed explanation of the present invention in combination with the drawings and embodiments. It should be understood that the specific implementation manners here are only used to explain the present invention and are not used to limit the present invention.

[0038] The present invention improves the continuous optical power carrying capacity through a high continuous wave transmission broadening waveguide and a ring antenna array jointly optimized for sidelobe suppression ratio and thermal distribution uniformity, reduces the nonlinear loss and heat accumulation of the silicon waveguide and the radiation array, improves the beam quality and detection performance, and is applicable to high-power beam detection systems such as lidar. The ring array silicon-based optical phased array chip of the present invention can achieve two-dimensional scanning, and also has advantages such as a high sidelobe suppression ratio and high integration.

[0039] The first aspect of the present invention provides a ring array silicon-based optical phased array chip applicable to high power.

[0040] As Figure 1As shown in the figure, the ring-array silicon-based optical phased array chip of the present invention includes a coupling grating module 1, a cascaded beam splitting module 2, a phase modulation module 3, a two-dimensional antenna ring array module 4, and a high-power broadening waveguide 6. The coupling grating module 1 is used to receive the incident light beam. The cascaded beam splitting module 2 is used to split the incident light beam into multiple unmodulated detection light beams. The phase modulation module 3 is used to perform phase modulation on each unmodulated light beam to generate a phase-modulated detection light beam. The two-dimensional antenna ring array module 4 is used to emit all the phase-modulated detection light beams upward outside the chip to achieve two-dimensional scanning of the light beam. The high-power broadening waveguide 6 is used as the light beam transmission channel on the ring-array silicon-based optical phased array chip.

[0041] Specifically, as Figure 1 and Figure 3 shown, the two-dimensional antenna ring array module 4 adopts an axisymmetric structure, which is mainly composed of at least one concentric two-dimensional antenna ring array arranged at intervals from the inside to the outside along the radial direction. Each two-dimensional antenna ring array is mainly composed of a plurality of two-dimensional grating antennas 41 arranged uniformly along the circumference. Among them, the two-dimensional antenna ring array module 4 adopting an axisymmetric structure means that all the two-dimensional grating antennas 41 in the same two-dimensional antenna ring array are arranged in an axisymmetric manner, and all the two-dimensional antenna ring arrays share the same axis of symmetry, and this axis of symmetry is the axis of symmetry of the two-dimensional antenna ring array module 4. This uniform circular aperture architecture with symmetric characteristics used in the present invention can break through the physical limitations of the traditional arranged array and at the same time achieve the scanning ability through ring phase compensation.

[0042] Specifically, the cascaded beam splitting module 2 includes a first-stage beam splitter and two beam splitting cascaded networks, which are respectively arranged on both sides of the two-dimensional antenna ring array module 4 and are symmetrically arranged with respect to the axis of symmetry of the two-dimensional antenna ring array module 4. The input end of the first-stage beam splitter is connected to the output end of the coupling grating module 1 through the high-power broadening waveguide 6. The two output ends of the first-stage beam splitter are respectively connected to the input ends of the two beam splitting cascaded networks through the high-power broadening waveguide 6. The output end of each beam splitting cascaded network is connected to the two-dimensional antenna ring array module 4 on the same side through the high-power broadening waveguide 6.

[0043] Specifically, the phase modulation module 3 includes two phase shifter arrays, which are respectively arranged above the output ends of the two beam splitting cascaded networks.

[0044] Specifically, the output end of each spectroscopic cascaded network includes N branch output waveguides, and the branch output waveguides are arranged at equal intervals along the symmetry axis direction of the two-dimensional antenna circular array module 4. Each phase shifter array includes N phase shifters, and the phase shifters are arranged at equal intervals along the symmetry axis direction of the two-dimensional antenna circular array module 4. The two-dimensional antenna circular array module 4 includes 2N two-dimensional grating antennas 41, that is, N two-dimensional grating antennas 41 are arranged on each side of the symmetry axis of the two-dimensional antenna circular array module 4.

[0045] For the part of the two-dimensional antenna circular array module 4 on one side of the symmetry axis, as well as the spectroscopic cascaded network and the phase shifter array on the same side, the number of branch output waveguides in the spectroscopic cascaded network, the phase shifters in the phase shifter array, and the two-dimensional grating antennas 41 in the two-dimensional antenna circular array module 4 are the same and in one-to-one correspondence. A phase shifter is arranged corresponding to and aligned above the branch output waveguide (as Figure 2 shown), and the phase shifter is used to perform phase modulation on the unmodulated light beam of the corresponding branch output waveguide arranged below itself. The branch output waveguide is connected to the corresponding two-dimensional grating antenna 41 through a high-power broadening waveguide 6 in the form of Manhattan routing, and then the phase-modulated detection light beam generated by its corresponding phase shifter is output to the corresponding two-dimensional grating antenna 41 through the high-power broadening waveguide 6.

[0046] Specifically, as Figure 4 shown, the two-dimensional grating antenna 41 is mainly composed of three L-shaped grating structures 412 and two grating structure gaps 411. The two-dimensional periodic arrangement of the L-shaped grating structures 412 can control the output light field in the vertical direction (z direction), enhance the directivity and optimize the beam divergence characteristics, and reduce energy loss. The grating gap 411 further realizes precise wavefront control by adjusting the phase distribution, and is suitable for high-precision optical phased array optical systems. The grating structure optimizes the divergence of the optical waveguide and free space light through mode matching. The adjustability of the grating period, duty cycle and gap size enables the antenna operating frequency and radiation angle characteristics to be customized according to the requirements of the circular array, and adapts to different array structures. The horizontal projection shapes of the L-shaped grating structures 412 and the grating structure gaps 411 are both arc-shaped, the vertical projection shape of the L-shaped grating structures 412 is L-shaped, and the three L-shaped grating structures 412 are arranged in sequence along the radial direction of the fan-shaped horizontal area. Two adjacent L-shaped grating structures 412 are connected by a grating structure gap 411; the L-shaped grating structure 412 located in the innermost part of the fan-shaped area is connected to the high-power broadening waveguide 6 through a transition waveguide. The horizontal projection shape of the transition waveguide is a truncated fan shape. The arc side of the transition waveguide is connected to the inner L-shaped grating structure 412, and the opposite side of the arc side is connected to the high-power broadening waveguide 6. Among them, the truncated fan shape is composed of three straight sides and an arc side, and the two straight sides adjacent to the arc side are collinear with the two sides of the horizontal projection of the fan-shaped area respectively.

[0047] Specifically, for two two-dimensional grating antennas 41 that are symmetric in the same two-dimensional antenna ring array, the line connecting the centers of the fan-shaped regions to which the two two-dimensional grating antennas 41 belong is perpendicular to the axis of symmetry of the two-dimensional antenna ring array module 4.

[0048] Furthermore, as Figure 2 shown, the ring array silicon-based optical phased array chip mainly consists of a silicon substrate layer, a buried layer, a thick silicon layer (Si waveguide layer), a cladding layer (SiO2 cladding layer), and a phase modulation layer (metal electrode layer) that are stacked in sequence from bottom to top. The top surface of the thick silicon layer is formed with a coupling grating module 1, a cascaded beam splitting module 2, a two-dimensional antenna ring array module 4, and a high-power broadening waveguide 6 through etching. The high-power broadening waveguide 6 is formed through full etching. In the same ring array silicon-based optical phased array chip, the waveguide width of the high-power broadening waveguide 6 is fixed and is selected from 800 nm to 1300 nm. The high-power broadening waveguide 6 has a higher power transmission limit compared to a single-mode waveguide and effectively avoids an increase in device size and deterioration of chip integration. The phase modulation layer includes a phase modulation module 3 deposited on the top surface of the cladding layer, and the phase shifter is deposited on the top surface of the cladding layer above the corresponding branch output waveguide.

[0049] Preferably, the thickness of the thick silicon layer is 500 nm. The high-power broadening waveguide 6 uses waveguide broadening design to effectively expand the mode field area, reduce the power density per unit area, thereby significantly reducing the nonlinear loss, and has a higher power transmission limit compared to a single-mode waveguide.

[0050] Preferably, the incident light beam includes continuous light in the infrared band with a power reaching the watt level.

[0051] Preferably, the incident light beam includes continuous light with a wavelength of 1500 nm and a power reaching the watt level.

[0052] Preferably, the beam splitting cascaded network is mainly composed of multiple levels of Y-branch beam splitters or 3 dB multimode interference couplers in cascade, and the number of cascades is adapted to the number of two-dimensional grating antennas 41 in the two-dimensional antenna ring array module 4, so that the number of two-dimensional grating antennas 41 on one side of the axis of symmetry of the two-dimensional antenna ring array module 4 is the same as the number of branch output waveguides of the beam splitting cascaded network on the same side.

[0053] Preferably, the bent part of the optical channel on the ring array silicon-based optical phased array chip uses an Euler bent waveguide 5, and the Euler bent waveguide 5 is formed on the top surface of the thick silicon layer through etching.

[0054] Preferably, the phase shifter uses a metal thermo-optic phase shifter and is formed above the cladding layer through metal evaporation.

[0055] Preferably, the coupled grating module 1 adopts a two-dimensional annular coupled grating; the coupled grating module 1 is formed on the top surface of the thick silicon layer through etching treatment.

[0056] Preferably, each two-dimensional antenna annular array includes the same number of two-dimensional grating antennas 41.

[0057] Furthermore, the number of two-dimensional antenna annular arrays, the radial spacing between rings, and the element spacing of each two-dimensional antenna annular array can be optimized by a genetic algorithm according to the far-field beam sidelobe suppression ratio and the thermal distribution uniformity. Among them, the radial spacing between rings refers to the radial spacing between two adjacent two-dimensional antenna annular arrays. The element spacing refers to the circumferential spacing between two adjacent two-dimensional grating antennas 41 in the two-dimensional antenna annular array. The circumferential spacing refers to the distance along the circumferential direction of the two-dimensional antenna annular array.

[0058] As a preferred embodiment of the present invention, when the wavelength of the incident beam is 1550 nm, the thickness of the thick silicon layer is 500 nm, the etching depth of the high-power broadening waveguide 6 is 500 nm, the width of the high-power broadening waveguide 6 is 800 nm, the etching depth of the grating structure gap 411 is 500 nm, and the etching depth of the L-shaped grating structure 412 is 130 nm; N is 32, the number of two-dimensional antenna annular arrays is 2, the two-dimensional grating antennas 41 in the two two-dimensional antenna annular arrays are the same, the outer ring aperture is 720 μm, and the inner ring aperture is 500 μm. This array provides a sidelobe suppression ratio of more than 10.2 dB, effectively solves the thermal accumulation problem in the case of high-power continuous waves and the mode crosstalk between thick silicon broadening waveguides through spacing control, and at the same time ensures that the heat in the designed phase shifter array is reasonably controlled.

[0059] The second aspect of the present invention provides an optimization method for the above-mentioned annular array silicon-based optical phased array chip.

[0060] The optimization method of the present invention includes the following steps: using a genetic algorithm, establishing a fitness function according to the far-field beam sidelobe suppression ratio and the thermal distribution uniformity, each individual includes the number of two-dimensional antenna annular arrays, the radial spacing between rings, and the element spacing of each two-dimensional antenna annular array, after multiple generations of selection, crossover, and mutation operations, after meeting the termination conditions, an optimal individual is obtained, and an annular array silicon-based optical phased array chip is manufactured and obtained according to the number of two-dimensional antenna annular arrays, the radial spacing between rings, and the element spacing of each two-dimensional antenna annular array in the optimal individual.

[0061] Preferably, the fitness function is set according to the following formula: f = SLSR - αp1 - βp2 - γp3 In the formula, f represents the fitness, SLSR represents the far-field beam sidelobe suppression ratio, p1 represents the penalty of the outer ring aperture, p2 represents the penalty of the element spacing, p3 represents the penalty of the radial spacing between rings, α represents the first weight coefficient, β represents the second weight coefficient, and γ represents the third weight coefficient.

[0062] Among them, the three penalties are set according to the following formulas respectively: p1 = max[0, ∑(A m - A max ) / A max p2 = max[0, (d min - d e ) / d min p3 = max[0, (1.2A m - A m+1 ) / A m In the formula, max[ ] represents the maximum value function, A m represents the aperture of the mth two-dimensional antenna circular array, A max represents the maximum outer ring aperture limit, d e represents the minimum element spacing limit, d min represents the minimum spacing between any two elements; Among them, the far-field beam sidelobe suppression ratio is obtained through the following process: the radiation pattern is obtained according to the array factor and the far-field distribution of a single antenna, and the far-field beam sidelobe suppression ratio is extracted from the radiation pattern according to the following formula: SLSR = 10log 10 (I main / I side ) In the formula, I main represents the main lobe peak power, I side represents the maximum sidelobe peak power.

[0063] When the main beam points to the direction of (u0, v0), the array factor F(u, v, u0, v0) is expressed by the following formula: F(u, v, u0, v0) = ∑ M m=1 ∑ Nm N=1 E m,n e^[jkr m ((cosφ m,n (u - u0) + sinφ m,n (v - v0)] In the formula, (u0, v0) represents the main lobe direction after phase calibration, (u, v) represents the main lobe direction before phase calibration; E​​​m,n represents the electric field strength of the nth two-dimensional grating antenna 41 in the mth ring, M represents the number of two-dimensional antenna ring arrays, and N m represents the total number of two-dimensional grating antennas 41 in the mth ring, j represents the imaginary unit, k represents the free space wave number, and r m represents the radius of the mth ring, that is, the distance from the array center to the mth ring; φ m,n represents the azimuth angle of the nth two-dimensional grating antenna in the mth ring.

[0064] Among them, the free space wave number k is obtained through the following formula: k = 2π / λ In the formula, λ represents the wavelength of the incident light beam.

[0065] The two direction cosine parameters of the main lobe direction are respectively obtained through the following formulas: u = sinφcosθ v = sinθcosφ In the formula, φ represents the azimuth angle of the main lobe direction, and θ represents the elevation angle of the main lobe direction.

[0066] Furthermore, the optimization method of the present invention further includes the following steps: in each phase shifter array, the phase shifters are arranged at equal intervals along the symmetry axis direction, the spacing between adjacent phase shifters is obtained through a simulation method, the width of the phase shifter array in the symmetry axis direction is calculated according to the number and spacing of the phase shifters, and the maximum outer ring aperture is set according to the width of the phase shifter array in the symmetry axis direction.

[0067] Specifically, the device fabrication includes two electron beam exposures and inductively coupled plasma etching. The first exposure and etching are used to define the waveguide structure, and the second exposure and etching are used to form the grating overlay structure in the optical coupling unit and the two-dimensional grating antenna.

[0068] Preferably, the manufacturing process of the ring array silicon-based optical phased array chip is specifically as follows: Perform the first electron beam exposure and inductively coupled plasma etching on the top surface of the thick silicon layer, and the etching depth is full etching to form the main waveguide structure; the main waveguide structure includes the grating structure gap 411, Euler bending waveguide 5, and high-power broadening waveguide 6 in the coupling grating module 1, cascaded beam splitting module 2, and two-dimensional antenna ring array module 4; Perform the second electron beam exposure and inductively coupled plasma etching on the top surface of the thick silicon layer, and the etching depth is shallow etching. The depth of the shallow etching is less than the full etching to form the grating overlay structure. The overlay depth (i.e., the depth of the shallow etching) is optimized with the coupling efficiency and the upward radiation efficiency of the antenna elements as the goals; the grating overlay structure includes the coupling grating module 1 and the L-shaped grating structure 412 in the two-dimensional antenna ring array module 4; A cladding layer is formed on the top surface of the thick silicon layer; A deposition process is performed on the top surface of the cladding layer to form a phase modulation layer mainly composed of the phase modulation module 3.

[0069] Optionally, the deposition process adopts processes such as photolithography, metal evaporation, or lift-off.

[0070] The specific embodiments of the present invention are as follows: Embodiment

[0071] In this embodiment, the wavelength of the incident light beam is 1500 nm. As Figure 1 shown, the ring array silicon-based optical phased array chip includes a coupling grating module 1, a cascaded beam splitting module 2, a phase modulation module 3, a two-dimensional antenna ring array 4, an Euler bent waveguide 5, and a high-power broadening waveguide 6. These device structures are all fabricated using silicon-on-insulator (SOI) materials with a silicon layer thickness of 500 nanometers and integrated on the same chip. The chip integration size is 3 mm × 2.5 mm, and it includes a total of 64 two-dimensional grating antennas 41.

[0072] The coupling grating module 1 adopts a two-dimensional ring coupling grating and is formed on the top surface of the thick silicon layer through an etching process. The incident direction of the incident light beam and the transmission direction of the light beam in the coupling grating module 1 are both aligned with the axis of symmetry of the two-dimensional antenna ring array module 4.

[0073] The cascaded beam splitting module 2 is mainly composed of 63 1×2 multimode interference coupler beam splitters cascaded in multiple stages. Except for the first-stage beam splitter, the other multimode interference coupler beam splitters and the input and output waveguides are divided into two groups, which are placed symmetrically with respect to the x-axis. Except for the first-stage beam splitter, the other multimode interference coupler beam splitters are arranged along the y-direction.

[0074] The phase modulation module 3 includes two phase shifter arrays, and the phase shifters adopt silicon-based thermo-optic phase shifters. By applying power boundary conditions at the device heating electrodes through thermal simulation, solving the temperature field distribution, obtaining the thermal distribution model of the overall area of the waveguide and the phase shifter, and introducing optical simulation to solve the optical field change, the high-performance thermo-optic phase shifter parameters under high-temperature conditions are obtained. The size of each optimized thermo-optic phase shifter is 200 μm × 2 μm, and the spacing is 50 μm, avoiding heat accumulation in high-power scenarios caused by dense electrodes, providing heat dissipation characteristics and a stable 2π phase shift ability. As Figure 2 shown, each thermo-optic phase shifter uses 200 nm thick metal as the conductive material and is deposited above the silica cladding layer (corresponding to Figure 2 the metal electrode layer in

[0075] The two-dimensional antenna circular array 4 forms a circularly symmetric structure by distributing two-dimensional grating antennas 41 at equal angles on concentric rings. In this embodiment, as Figure 4 shown, the grating structure gap 411 is 0.56 μm, the period of the L-shaped grating structure 412 is 1.26 μm, the duty cycle is 0.476, providing an upward radiation efficiency higher than 50%. The overall size of the L-shaped grating structure 41 is 10.7 μm × 6 μm, its 1 dB bandwidth exceeds 100 nm and the 3 dB envelope is 21.4° × 18.7°.

[0076] As Figure 3 shown, this uniform circular aperture architecture with symmetric characteristics can achieve scanning ability through annular phase compensation. For a circular optical phased array structure composed of m concentric rings (the number of array elements N m in the m-th concentric ring, and the corresponding ring radius R m ), all radiation units (two-dimensional grating antennas 41) are set as isotropic point sources. Under this condition, when the main beam points to the direction of (u0, v0), the expression of the array factor F(u, v, u0, v0) is: F(u, v, u0, v0)=∑ M m=1 ∑ Nm N=1 E m,n e^[jkr m ((cosφ m,n (u - u0)+sinφ m,n (v - v0)] In the formula, (u0, v0) represents the main lobe direction after phase calibration, (u, v) represents the main lobe direction before phase calibration; E m,n represents the electric field strength of the n-th two-dimensional grating antenna 41 in the m-th ring, M represents the number of two-dimensional antenna circular arrays, N m represents the total number of two-dimensional grating antennas 41 in the m-th ring, j represents the imaginary unit, k represents the free space wave number, r m represents the radius of the m-th ring, that is, the distance from the array center to the m-th ring, φ m,n represents the azimuth angle of the n-th two-dimensional grating antenna in the m-th ring.

[0077] In this embodiment, a dynamic optimization scheme based on the genetic algorithm is used. Through multi-parameter joint regulation (sidelobe suppression ratio, number of rings, radial spacing, and element spacing) and multi-objective collaborative optimization (far-field beam sidelobe suppression ratio and thermal uniformity), that is, using the genetic algorithm to dynamically optimize the array structure, and setting forced constraints with the process limitations of the minimum element spacing and the maximum aperture size, the beam performance and robustness under high-power continuous wave are significantly improved.

[0078] In this embodiment, the fitness function includes the far-field beam sidelobe suppression ratio determined by the array factor formula and the thermal distribution uniformity determined by the number of rings, the radial spacing, and the element spacing. The initial population size is set to 100, the crossover probability is 0.6, and the mutation rate is 0.002. 64 units are selected in combination with random heuristic individuals to balance the diversity of the search space and the early convergence efficiency. The fitness evaluation is performed for each generation through the fitness function.

[0079] For the individuals in each generation population, the fitness is calculated through the following process: The radiation pattern is obtained according to the array factor and the far-field distribution of a single antenna, and the far-field beam sidelobe suppression ratio is extracted from the radiation pattern according to the following formula: SLSR = 10log 10 (I main / I side ) In the formula, I main represents the main lobe peak power, and I side represents the maximum sidelobe peak power.

[0080] The fitness is calculated according to the fitness function: f = SLSR - αp1 - βp2 - γp3 In the formula, f represents the fitness, SLSR represents the far-field beam sidelobe suppression ratio, p1 represents the penalty amount of the outer ring aperture, p2 represents the penalty amount of the element spacing, p3 represents the penalty amount of the radial spacing between rings, α represents the first weight coefficient, β represents the second weight coefficient, and γ represents the third weight coefficient; in this embodiment, the three weight coefficients are respectively set to 5, 3, and 2.

[0081] The three penalty amounts are respectively set according to the following formulas: p1 = max[0, ∑(A m - A max ) / A max ) p2 = max[0, (d min - d e ) / d min ) p3 = max[0, (1.2A m - A m+1 ) / A m ) In the formula, max[ ] represents the maximum value function, A m represents the aperture of the m-th ring, A max represents the maximum outer ring aperture limit, d e represents the minimum element spacing limit, and d min represents the minimum spacing between any two elements.

[0082] Among them, the maximum outer ring aperture is set according to the total width of the phase shifter array in the x direction, which is set to 1100 μm in this embodiment. The minimum element spacing is set according to the crosstalk simulation between elements, which is set to 30 μm in this embodiment. The expansion rule between rings in this embodiment is set as follows: the radial spacing of the outer ring increases by more than 1.2 times the inner ring aperture, that is, N k+1 ≥1.2N k , ensuring uniform distribution of the multi-ring power density and preventing heat accumulation caused by too small spacing between multi-rings.

[0083] The optimization results are as Figure 5 shown. In the double-ring two-dimensional antenna ring array module 42, the outer ring antenna array 421 has an aperture of 720 μm, the inner ring antenna array 422 has an aperture of 500 μm, the radial spacing between them is 110 μm, and the minimum element spacing within the ring is 49 μm, providing good element uniformity, and thus providing good thermal management performance and simple output waveguide routing complexity.

[0084] Perform high-precision far-field beam simulation on the parameter combination corresponding to the optimal individual, and the results are as Figure 6 shown. The far-field spot at the center point has a sidelobe suppression ratio greater than 10.2 dB. This index reflects that this array effectively reduces the radiation interference in the non-main beam direction, provides the high directivity and low signal interference ability of the outgoing beam system, and meets the beam detection requirements of application scenarios such as lidar.

[0085] High-power broadening waveguide 6. In this embodiment, the high-power broadening waveguide 6 is based on a 500-nm-thick silicon layer and uses waveguide broadening design to effectively expand the mode field area, reduce the power density per unit area, thereby significantly reducing the nonlinear loss, and having a higher power transmission upper limit compared with a single-mode waveguide.

[0086] It is worth explaining that in the characteristics of high-power scenarios, the two main nonlinear losses suffered by silicon materials include two-photon absorption (TPA) and free carrier absorption effect (FCA). Both will greatly limit the average power level that the silicon waveguide can stably transmit, and the losses increase with the high power of the light intensity per unit area. After the input power exceeds a certain threshold, it will cause the nonlinear loss in the waveguide to rise and cause serious thermal effects or device damage. At the same time, the broadening waveguide based on the traditional 220-nm-thick silicon layer platform will cause a significant increase in the size of the device structure and deterioration of performance. The waveguide structure design of the present invention comprehensively optimizes aspects such as nonlinear loss, device size, coupling efficiency, and manufacturing process.

[0087] In the continuous-wave light propagation process in the silicon waveguide, the light intensity I is affected by linear loss, two-photon absorption, and free carrier absorption at the same time. The total loss equation can be expressed as: dI / dz = -αI - β TPA I 2 -β FCA I 3 In the formula, I represents the distribution of the optical power along the waveguide propagation direction z on the cross-section, and the specific value is I = P / A eff , where P is the input continuous-wave optical power, and A eff is the mode area of the waveguide, α is the linear propagation loss coefficient, and β TPA and β FCA are the nonlinear coefficients corresponding to the two-photon absorption and free-carrier absorption effects, respectively.

[0088] It can be seen from the total loss equation that the generation of the two nonlinear effects of TPA and FCA is due to the high local optical intensity of the waveguide cross-section. In the case of high-power continuous-wave light input, both of them will significantly limit the optical power that can be stably transmitted in the silicon waveguide. Since the thick silicon waveguide and waveguide broadening design can reduce the optical power density per unit area, it is possible to reduce the nonlinear effects including TPA and FCA, and reduce the optical loss and signal distortion. Therefore, in high-power and long-distance transmission, the high-power broadened waveguide 6 in the present invention can ensure the stable transmission of high-power continuous-wave light while maintaining a high transmission efficiency. However, directly increasing the thickness of the silicon layer or broadening the waveguide on a traditional design platform will lead to a decrease in the device integration density, and thus deteriorate the integration area of the on-chip system. The silicon waveguide for high-power applications needs to be comprehensively designed and the performance verified through specific experiments.

[0089] Based on this, in this embodiment, a 500-nm-thick silicon layer is used as the chip design platform, and the waveguide widths are 800 nm and 1300 nm respectively. By introducing a non-traditional thick silicon layer platform and waveguide broadening strategy, the waveguide mode area is expanded to ~2.67 or ~4.33 times that of the single-mode waveguide reference design, respectively, to balance the requirements of high-power transmission and integration density.

[0090] For the Euler bent waveguide 5, in this embodiment, a compact Euler bent waveguide is used, that is, a bent waveguide optimized by Euler bending. The bent parts between all devices are connected by a bent waveguide optimized by Euler bending, providing low-loss and high-order mode suppression characteristics. In this embodiment, the maximum curvature radius R max is 500 μm for the thick silicon bent waveguide optimized by the Euler curve, and its equivalent bending radius is 12 μm. In the 50-nm bandwidth range at the central wavelength of 1550 nm, the insertion loss is less than 0.01 dB.

[0091] In this embodiment, the device fabrication includes two electron beam lithographies and inductively coupled plasma etching. The first exposure and etching are used to form the main structure with an etching depth of 500 nm. The second exposure and etching are used to form the coupled grating module 1 and the L-shaped grating structure in the two-dimensional grating antenna 41 with an etching depth of 130 nm. By selecting the optimized etching depth of 130 nm for overlay in this embodiment, high coupling efficiency and upward radiation efficiency of the antenna elements are achieved.

[0092] Embodiment 2 In this embodiment, the power improvement effect of the high-power broadened waveguide 6 is verified through experiments.

[0093] The specific experimental process is as follows: The experimental setup system adopts a cascaded structure of a tunable laser (TL) and an erbium-doped fiber amplifier (EDFA). The continuous wave output power is stably adjusted from 0 to the order of 1.1 W through a precision power control module. The polarization control is used to ensure the coupling efficiency of the grating in the experiment, and a power meter is used to synchronously monitor the input / output power to accurately evaluate the total insertion loss.

[0094] In this embodiment, the lengths of the three groups of test waveguides are fixed at 1 mm. The test waveguides are fabricated based on the standard CMOS process, including two electron beam lithographies and inductively coupled plasma etching. The first exposure and etching are used to define the waveguide structure, and the second exposure and etching are used to form the input coupling grating structure. The system uses an optical power meter to quantify the input and output optical powers and calculates the total insertion loss; the waveguide transmission power is the power transmission value inside the waveguide after compensating for the insertion loss of the unilateral coupling grating; the width of the single-mode waveguide fabricated based on the thick silicon platform is 300 nm, and its mode field area is similar to that of the existing 220-nm silicon layer. Moreover, the three groups of waveguides adopt exactly the same coupling grating and are integrated on the same chip; the instruments and parameter settings used in the experiments on the three groups of waveguides are kept consistent, demonstrating the significance of this comparative experiment.

[0095] The experimental results are as Figure 7 and Figure 8 shown. It can be seen that the overall insertion loss and growth rate of the single-mode waveguide are greater than those of the broadened waveguide. When the input power reaches more than 800 mW, the single-mode waveguide can no longer maintain high-power continuous light transmission, quantifying the limitation of its restricted cross-sectional area on the power-carrying capacity. At the same time, the total insertion loss growth trend of the two groups of broadened waveguides is slower. Since the light intensity per unit area decreases under the same input power, the nonlinear effect is weakened, which is consistent with the theory.

[0096] No structural damage was observed in the 800 nm and 1300 nm broadened waveguides at a continuous wave optical input power of 1.1 W, corresponding to a higher power upper limit threshold; no structural damage was observed in the coupling grating at a continuous wave optical input power of 1.1 W, also corresponding to a higher power upper limit threshold.

[0097] Overall, the broadened waveguides of the two groups of 500 nm silicon layers have significant applicability in high-power scenarios. The 1300 nm broadened waveguide has a higher power transmission threshold, but the combined mode mismatch losses caused by the propagation loss and sidewall roughness introduced during the manufacturing process result in an increase in losses in the input power range of 0.2 W - 0.8 W. In contrast, the 800 nm broadened waveguide has more stable loss characteristics and is preferably used in the high-power applicable two-dimensional optical phased array chip in Example 1.

[0098] In summary, in the present invention, the design of the annular array breaks the uniform spacing and strict periodicity rules of the traditional array by introducing annular symmetry, and solves the problems of the traditional rectangular array. Since the array elements are evenly distributed in physical space, more units need to be connected in the central area of the array, making the waveguide paths complex, resulting in crosstalk between waveguides, affecting the beam quality, and the complexity of the dense waveguides in the central area of the high-integration array will bring corresponding heat accumulation and other problems. Its key advantages are reflected in the following aspects: The array units of the annular array are not concentrated in the center but are distributed on different ring layers. The distance between the array units on each ring layer is more evenly distributed. Compared with the traditional array, the array units will not be densely stacked in the central area, thus providing excellent thermal uniformity in the case of high-power continuous wave; at the same time, by allowing more rings to be added or increasing the number of units on the ring, the annular array can effectively expand the array scale without sacrificing system performance. Compared with the traditional equally spaced array layout, the annular array can avoid the problem of dense and overlapping wiring, thus reducing the wiring complexity and signal interference. The characteristic of its evenly distributed array units makes the wiring simple and efficient, meeting the requirements of high power and large-scale integration.

[0099] Above, the present invention has been introduced in detail, and the specific embodiments and corresponding principles applied in the present invention have been elaborated in detail. The above embodiments are only used to facilitate the understanding of the present invention and its core features. It should be noted that for those skilled in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can still be made to the present invention, and these improvements and modifications are also included in the protection scope of the claims of the present invention.

Claims

1. A ring array silicon-based optical phased array chip applicable to high power, characterized in that Comprising: A coupled grating module (1) for receiving an incident light beam; A cascaded beam splitting module (2) for splitting the incident light beam into multiple unmodulated detection light beams; A phase modulation module (3) for performing phase modulation on each unmodulated light beam to generate a phase-modulated detection light beam; A two-dimensional antenna ring array module (4) for emitting all the phase-modulated detection light beams outside the chip; adopting an axisymmetric structure, mainly composed of at least one concentric two-dimensional antenna ring array arranged at intervals from the inside to the outside along the radial direction, and each two-dimensional antenna ring array is mainly composed of a plurality of two-dimensional grating antennas (41) arranged uniformly along the circumference; A high-power broadening waveguide (6) for serving as an optical channel.

2. The annular array silicon-based optical phased array chip applicable to high power according to claim 1, wherein: The cascaded beam splitting module (2) includes a first-stage beam splitter and two beam splitting cascade networks, the two beam splitting cascade networks are symmetrically arranged on both sides of the two-dimensional antenna ring array module (4), the input end of the first-stage beam splitter is connected to the output end of the coupled grating module (1), the two output ends of the first-stage beam splitter are respectively connected to the input ends of the two beam splitting cascade networks, and the output end of each beam splitting cascade network is connected to the two-dimensional antenna ring array module (4) on the same side; The phase modulation module (3) includes two phase shifter arrays, and the two phase shifter arrays are respectively arranged above the output ends of the two beam splitting cascade networks; For the beam splitting cascade network, the phase shifter array and the two-dimensional antenna ring array module (4) on the same side, the number of the branch output waveguides, the phase shifters and the two-dimensional grating antennas (41) is the same and they correspond one by one. A phase shifter is arranged corresponding and aligned above the branch output waveguide, and the branch output waveguide is connected to the corresponding two-dimensional grating antenna (41) through the high-power broadening waveguide (6) in the form of Manhattan routing.

3. The ring array silicon-based optical phased array chip applicable to high power according to claim 2, wherein: The two-dimensional grating antenna (41) is mainly composed of three L-shaped grating structures (412) and two grating structure gaps (411); the horizontal projection shapes of the L-shaped grating structures (412) and the grating structure gaps (411) are both arc-shaped, the vertical projection shape of the L-shaped grating structure (412) is L-shaped, the three L-shaped grating structures (412) are arranged in sequence along the radial direction within the same fan-shaped area, and two adjacent L-shaped grating structures (412) are connected by a grating structure gap (411); the L-shaped grating structure (412) located inside is connected to the high-power broadening waveguide (6) through a transition waveguide, and the horizontal projection shape of the transition waveguide is a truncated fan-shaped; for two two-dimensional grating antennas (41) that are symmetrical in the same two-dimensional antenna ring array, the connecting line of the centers of the two fan-shaped areas is perpendicular to the symmetry axis of the two-dimensional antenna ring array module (4).

4. The annular array silicon-based optical phased array chip according to claim 1, wherein: The annular array silicon-based optical phased array chip is mainly composed of a silicon substrate layer, a buried layer, a thick silicon layer, a cladding layer, and a phase modulation layer arranged in a stacked manner from bottom to top; the coupling grating module (1), the cascaded beam splitting module (2), the two-dimensional antenna annular array module (4), and the high-power broadening waveguide (6) are formed on the top surface of the thick silicon layer through etching treatment. The high-power broadening waveguide (6) is formed through full etching treatment, and the waveguide width of the high-power broadening waveguide (6) is selected from 800 nm to 1300 nm; the phase modulation layer includes a phase modulation module (3) deposited on the top surface of the cladding layer, and the phase shifter is deposited above the corresponding branch output waveguide; the incident light beam includes continuous light in the infrared band with a power reaching the watt level.

5. The annular array silicon-based optical phased array chip according to claim 4, characterized in that: The annular array silicon-based optical phased array chip satisfies at least one of the following characteristics: The beam splitting cascaded network is mainly composed of cascaded multi-stage Y-branch beam splitters or 3dB multimode interference couplers, and the number of cascades is adapted to the number of two-dimensional grating antennas (41) in the two-dimensional antenna annular array module (4); The bent part of the optical channel on the annular array silicon-based optical phased array chip adopts an Euler bent waveguide (5); the Euler bent waveguide (5) is formed on the top surface of the thick silicon layer through etching treatment; The phase shifter adopts a silicon-based thermo-optic phase shifter; The coupling grating module (1) adopts a two-dimensional annular coupling grating; Each two-dimensional antenna annular array includes the same number of two-dimensional grating antennas (41).

6. The annular array silicon-based optical phased array chip according to claim 4, wherein: The number of the two-dimensional antenna annular arrays, the radial spacing between rings, and the element spacing of each two-dimensional antenna annular array can be optimized by a genetic algorithm according to the far-field beam sidelobe suppression ratio and the thermal distribution uniformity.

7. The annular array silicon-based optical phased array chip according to claim 6, wherein: The wavelength of the incident light beam is 1550 nm, the thickness of the thick silicon layer is 500 nm, the width of the high-power broadening waveguide (6) is 800 nm, the etching depth of the grating structure gap (411) is 500 nm, and the etching depth of the L-shaped grating structure (412) is 130 nm; N is 32, the number of two-dimensional antenna annular arrays is two, the two-dimensional grating antennas (41) in the two two-dimensional antenna annular arrays are the same, the outer ring aperture is 720 μm, and the inner ring aperture is 500 μm.

8. An optimization method for the annular array silicon-based optical phased array chip as described in any one of claims 1 to 7, characterized in that, It includes the following steps: Using a genetic algorithm, a fitness function is established according to the far-field beam sidelobe suppression ratio and the thermal distribution uniformity. Each individual includes the number of two-dimensional antenna annular arrays, the radial spacing between rings, and the element spacing of each two-dimensional antenna annular array. After multiple generations of selection, crossover, and mutation operations, when the termination condition is met, the optimal individual is obtained, and the annular array silicon-based optical phased array chip is manufactured and obtained according to the number of two-dimensional antenna annular arrays, the radial spacing between rings, and the element spacing of each two-dimensional antenna annular array in the optimal individual.

9. The optimization method of the annular array silicon-based optical phased array chip according to claim 8, characterized in that: The fitness function is set according to the following formula: f = SLSR - αp1 - βp2 - γp3 In the formula, f represents the fitness, SLSR represents the far-field beam sidelobe suppression ratio, p1 represents the penalty of the outer ring aperture, p2 represents the penalty of the element spacing, p3 represents the penalty of the radial spacing between rings, α represents the first weight coefficient, β represents the second weight coefficient, and γ represents the third weight coefficient; the ranges of the three weight coefficients are 5 to 10, 2 to 5, and 1 to 3 respectively; The three penalties are set according to the following formulas respectively: p1 = max[0, ∑(A m -A max ) / A max ​ p2 = max[0, (d min -d e ) / d min )] p3 = max[0, (1.2A m -A m+1 ) / A m ) where max[ ] represents the maximum value function, A m represents the aperture of the m-th ring, A max represents the maximum outer ring aperture limit, d e represents the minimum element spacing limit, d min represents the minimum spacing between any two elements; The far-field beam sidelobe suppression ratio is obtained through the following process: obtain the radiation pattern according to the array factor and the single-antenna far-field distribution, and extract the far-field beam sidelobe suppression ratio from the radiation pattern according to the following formula: SLSR = 10log 10 (I main / I side ) where I main represents the main lobe peak power, and I side represents the maximum sidelobe peak power.

10. The optimization method of the ring array silicon-based optical phased array chip according to claim 9, characterized in that, It also includes the following steps: In each phase shifter array, the phase shifters are arranged at equal intervals along the symmetry axis direction. The spacing between adjacent phase shifters is obtained through the simulation method. The total width of the phase shifter array in the symmetry axis direction is calculated according to the number and spacing of the phase shifters, and the maximum outer ring aperture limit is set according to the total width of the phase shifter array in the symmetry axis direction.

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