Two-dimensional silicon-based optical phased array beam shaping method based on sparse aperiodic array

Abstract

The application relates to the field of optical phased array beam control technology and discloses a two-dimensional silicon-based optical phased array beam shaping method based on a sparse non-periodic array, which comprises the following steps: first, establishing an array element position model, generating an initial array element position set and a difference vector set, evaluating local periodicity according to a difference density distribution and adjusting the array element positions to obtain a sparse non-periodic array element position set; and then, constructing a target beam shape according to a target scanning direction, calculating a basic scanning phase, and jointly adjusting an amplitude weight and a phase correction amount to form a shaped beam. By constructing the difference vector set and generating the difference density distribution, the local periodicity is evaluated according to the difference vector gathering area, and the initial array element position set is adjusted in position, so that the positions of the array elements in the sparse non-periodic array element position set are distributed in a scattered manner, thereby reducing the off-axis energy gathering in a fixed direction and reducing the stray echo interference in a wind measurement radar.

Description

Technical Field

[0001] This invention relates to the field of optical phased array beam control technology, and in particular to a two-dimensional silicon-based optical phased array beam shaping method based on a sparse non-periodic array. Background Technology

[0002] Wind-measuring radar acquires wind speed and direction information by emitting lasers into the atmosphere and receiving backscattered echoes. To achieve rapid scanning in different directions, existing wind-measuring radars are increasingly adopting two-dimensional silicon-based optical phased arrays as the transmitting component. A two-dimensional silicon-based optical phased array typically consists of multiple optical radiation elements, each connected to a phase modulation unit. By controlling the output phase of each element, the emitted optical signals are coherently superimposed in the target direction, thus forming a scanning beam. In wind-measuring radar applications, when the emitted beam has high off-axis energy in a non-target direction, atmospheric scattering signals will enter the receiving channel from that direction, forming stray echoes.

[0003] However, in the process of realizing the technical solution of this application, the inventors of this application discovered that the existing two-dimensional silicon-based optical phased array design method lacks an evaluation and adjustment mechanism for the distribution of position differences between array elements, which makes it difficult to effectively disperse the repetitive position differences between array elements. As a result, the phenomenon of off-axis energy accumulation in a fixed direction still exists, which is prone to generating non-target direction stray echo interference during the transmission of wind measurement radar. Summary of the Invention

[0004] To overcome the above shortcomings, this invention provides a two-dimensional silicon-based optical phased array beam shaping method based on a sparse non-periodic array, aiming to improve the problem that existing technologies are prone to generating stray echo interference from non-target directions during the transmission of wind measurement radar.

[0005] This invention provides the following technical solution: a two-dimensional silicon-based optical phased array beam shaping method based on a sparse non-periodic array, comprising the following steps: S1. Obtain the number of array elements, chip deployment area, minimum array element spacing and target scanning direction of the two-dimensional silicon-based optical phased array, and establish a two-dimensional position model of each array element in the chip plane. S2. Generate an initial set of array element positions that satisfy the minimum spacing constraint of array elements within the deployable area of ​​the chip, and construct a set of difference vectors based on the position difference between any two array elements. S3. Generate a differential density distribution based on the differential vector set, identify differential vector clustering regions, and evaluate the local periodicity of the initial array element position set based on the differential vector clustering regions; S4. Adjust the position set of the initial array element positions according to the local periodicity, and perform array element minimum spacing constraint and chip deployable area constraint check during the position adjustment process to obtain a sparse non-periodic array element position set. S5. Construct the target beam shape according to the target scanning direction, and calculate the basic scanning phase of each element according to the sparse non-periodic element position set; S6. Under the condition that the positions of the sparse non-periodic array elements are fixed, the amplitude weight and phase correction of each array element are jointly adjusted according to the difference between the target beam shape and the actual far-field light intensity distribution, the off-axis energy distribution outside the main lobe region, the smoothness of the phase change between adjacent array elements, and the amplitude balance between each array element. The basic scanning phase and the phase correction are superimposed to obtain the final control phase, so as to form a shaped beam according to the amplitude weight and the final control phase.

[0006] Preferably, in step S2, the step of generating an initial set of array element positions that satisfies the minimum element spacing constraint within the deployable area of ​​the chip includes: Candidate deployment locations are determined according to a preset sparse occupancy ratio; Calculate the spacing between the candidate deployment positions and the positions of the already added array elements in sequence; When all the spacings are not less than the minimum spacing of the array elements, the candidate placement position is retained; When the number of array elements reaches the preset number, the initial array element position set is generated.

[0007] Preferably, in step S2, the step of constructing a set of difference vectors based on the positional difference between any two array elements includes: Select any two different array elements; Calculate the lateral and longitudinal position differences between two different array elements; The lateral position difference and the longitudinal position difference are combined into a difference vector; By traversing all different array element pairs, the set of difference vectors is obtained.

[0008] Preferably, in step S3, the step of evaluating the local periodicity of the initial array element position set based on the difference vector aggregation region includes: Multiple differential sampling positions are set within the differential plane; Calculate the degree of overlap of the difference vectors at each difference sampling position; Regions with an overlap exceeding a preset density threshold are defined as differential vector aggregation regions; Local periodic evaluation results are generated based on the number and concentration of the differential vector clustering regions.

[0009] Preferably, in step S4, the step of adjusting the position set of the initial array elements according to the local periodicity includes: Determine the target array elements of the corresponding difference vector clustering region; The perturbation is adjusted according to the degree of contribution of the target array element to the local periodicity; Regenerate the difference density distribution; When the differential density distribution meets the preset uniformity requirement, the sparse non-periodic array element position set is obtained.

[0010] Preferably, in step S4, the step of performing the minimum spacing constraint of array elements and the chip deployable area constraint check during the position adjustment process includes: Determine whether the array element after position adjustment is located within the deployable area of ​​the chip; Determine whether the spacing between the array element after position adjustment and other array elements is not less than the minimum spacing between array elements; When all of the above conditions are met, the positions of the array elements after the position adjustment are retained. Otherwise, rollback or re-disturbance will be performed.

[0011] Preferably, in step S5, the step of calculating the basic scanning phase of each array element based on the sparse aperiodic array element position set includes: Determine the center position of the target beam; The target beam shape is generated according to the preset main lobe shape parameters; The phase compensation relationship is determined based on the position of each array element; The basic scanning phase of each array element is calculated based on the phase compensation relationship.

[0012] Preferably, in step S6, the step of jointly adjusting the amplitude weights and phase corrections of each array element includes: Calculate the actual far-field light intensity distribution; divide the main lobe region and side lobe regions; Determine the sidelobe energy constraints, main lobe morphology errors, phase smoothing constraints, and amplitude equalization constraints; The amplitude weight and the phase correction amount are iteratively adjusted based on the main lobe morphology error, the side lobe energy constraint, the phase smoothing constraint, and the amplitude equalization constraint.

[0013] Preferably, the step of determining the sidelobe energy constraint includes: The angular region outside the main lobe region is divided into the target detection region, the transition region, and the non-target region; Set corresponding corner domain constraint weights for the target detection region, transition region, and non-target region respectively; Make the corner constraint weight of the non-target region greater than the corner constraint weight of the transition region, and make the corner constraint weight of the transition region greater than the corner constraint weight of the target detection region; Statistical analysis of off-axis energy distribution within each region; The sidelobe energy constraints are generated based on the off-axis energy distribution in each region and the corresponding angular domain constraint weights.

[0014] Preferably, in step S6, the step of forming a shaped beam based on the amplitude weight and the final control phase includes: The basic scanning phase of each array element is superimposed with the phase correction amount to obtain the final control phase; The amplitude weights and the final control phase are loaded into a two-dimensional silicon-based optical phased array; The shaping beam is formed by coherently superimposing the array elements.

[0015] The present invention has the following beneficial effects: 1. This invention constructs a set of differential vectors and generates a differential density distribution. It evaluates the local periodicity based on the aggregation region of the differential vectors and adjusts the position of the initial array element position set to disperse the position difference between array elements in the sparse non-periodic array element position set. This reduces off-axis energy accumulation in a fixed direction and reduces stray echo interference in the wind measurement radar.

[0016] 2. This invention constructs the target beam shape according to the target scanning direction, and adjusts the amplitude weight and phase correction of each array element according to the difference between the target beam shape and the actual far-field light intensity distribution, so that the actual far-field light intensity distribution matches the preset main lobe shape, thereby improving the beam energy concentration in the target detection direction of the wind measuring radar.

[0017] 3. This invention divides the angular domain outside the main lobe region into a target detection region, a transition region, and a non-target region, and sets different angular domain constraint weights to generate sidelobe energy constraints, thereby suppressing off-axis energy in non-target directions and improving the beam shape consistency of wind measuring radar under different scanning directions. Attached Figure Description

[0018] Figure 1 This is a flowchart of the two-dimensional silicon-based optical phased array beam shaping method based on a sparse non-periodic array proposed in this invention. Figure 2 This is a schematic diagram illustrating the element position optimization of the two-dimensional silicon-based optical phased array beam shaping method based on a sparse non-periodic array proposed in this invention. Figure 3 This is a schematic diagram of the beam shaping control of the two-dimensional silicon-based optical phased array beam shaping method based on a sparse non-periodic array proposed in this invention. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Reference Figure 1 This invention provides a two-dimensional silicon-based optical phased array beam shaping method based on a sparse non-periodic array, comprising the following steps: S1. Obtain the number of array elements, chip deployment area, minimum array element spacing and target scanning direction of the two-dimensional silicon-based optical phased array, and establish a two-dimensional position model of each array element in the chip plane. S2. Generate an initial set of array element positions that satisfy the minimum spacing constraint within the chip's deployable area, and construct a set of difference vectors based on the position difference between any two array elements. S3. Generate a differential density distribution based on the differential vector set, identify differential vector clustering regions, and evaluate the local periodicity of the initial array element position set based on the differential vector clustering regions. S4. Adjust the initial array element position set according to local periodicity, and perform array element minimum spacing constraint and chip deployable area constraint check during the position adjustment process to obtain a sparse non-periodic array element position set. S5. Construct the target beam shape according to the target scanning direction, and calculate the basic scanning phase of each element according to the sparse non-periodic element position set; S6. Under the condition that the positions of the sparse non-periodic array elements are fixed, the amplitude weight and phase correction of each array element are jointly adjusted according to the difference between the target beam shape and the actual far-field light intensity distribution, the off-axis energy distribution outside the main lobe region, the smoothness of the phase change between adjacent array elements, and the amplitude balance between each array element. The basic scanning phase and the phase correction are superimposed to obtain the final control phase, so as to form a shaped beam according to the amplitude weight and the final control phase.

[0021] Specifically, the number of elements, the deployable area of ​​the chip, the minimum element spacing, the operating wavelength, and the target scanning direction of the two-dimensional silicon-based optical phased array are first obtained. A two-dimensional coordinate system is then established on the chip surface to uniformly represent the position of each element within the chip plane. The deployable area of ​​the chip is used to limit the allowable deployment range of the elements, the minimum element spacing is used to limit the minimum physical interval between any two elements, and the target scanning direction is used to determine the pointing position of the shaping beam.

[0022] After modeling the array element positions, candidate placement positions are selected within the chip's deployable area according to a preset sparse duty cycle. The distance between each candidate placement position and the positions of already added array elements is then determined. When the distance between a candidate placement position and all already added array elements is not less than the minimum array element spacing, the candidate placement position is added to the initial array element position set. When the number of array elements in the initial array element position set reaches the preset number of array elements, the initial array element position set is generated.

[0023] After the initial set of array element positions is generated, iterate through any two different array elements in the set, calculate the position difference between the two elements in the horizontal and vertical directions, and combine the horizontal and vertical position differences to form a difference vector. Perform the above process on all different array element pairs to obtain the set of difference vectors. The set of difference vectors is used to represent the relative positional relationships between array elements.

[0024] After obtaining the set of difference vectors, multiple difference sampling locations are set in the difference plane, and the number of difference vectors or the degree of overlap of difference vectors near each difference sampling location are counted to generate a difference density distribution. Regions where the difference density exceeds a preset density threshold are identified as difference vector clustering regions, and local periodic evaluation results are generated based on the number, area, and concentration of difference vector clustering regions.

[0025] Based on the local periodicity evaluation results, target array elements corresponding to the differential vector aggregation regions are determined, and the order of position adjustment is determined according to the contribution of each target array element to the local periodicity. After performing position perturbation adjustments on the target array elements, the differential vector set and differential density distribution are regenerated, and the local periodicity evaluation results are recalculated.

[0026] During the position adjustment process, each adjusted array element position undergoes chip deployable area constraint checks and array element minimum spacing constraint checks. If the adjusted array element position is within the chip deployable area and the distance between it and other array elements is not less than the array element minimum spacing, the adjusted array element position is retained; otherwise, the adjustment is canceled, and the position perturbation process is re-executed. When the differential density distribution meets the preset uniformity requirements, the current array element position set is used as the sparse aperiodic array element position set.

[0027] After obtaining the set of sparse aperiodic array element positions, the target beam center position is determined according to the target scanning direction, and the target beam shape is generated based on preset main lobe morphology parameters. The target beam shape describes the two-dimensional angular domain energy distribution corresponding to the target scanning direction. Based on the positions of each element in the set of sparse aperiodic array element positions, the phase compensation relationship of each element in the target scanning direction is calculated, and the basic scanning phase of each element is generated accordingly. The basic scanning phase is used to ensure that the output optical signals of each element satisfy the coherent superposition condition in the target scanning direction.

[0028] Under the condition of a fixed set of sparse aperiodic array elements, the amplitude weight and phase correction of each element are used as parameters to be adjusted. The actual far-field light intensity distribution is calculated based on the element positions, amplitude weights, and phase control values, and the two-dimensional angular domain is divided into main lobe region and side lobe region.

[0029] The main lobe shape error is determined based on the difference between the target beam shape and the actual far-field intensity distribution within the main lobe region. The side lobe energy constraint is determined based on the off-axis energy distribution within the side lobe region. The phase smoothing constraint is determined based on the difference in phase correction between adjacent elements. The amplitude equalization constraint is determined based on the difference in amplitude weights among the elements.

[0030] When determining sidelobe energy constraints, the angular domain outside the main lobe region is divided into target detection region, transition region, and non-target region, and corresponding angular domain constraint weights are assigned to each. Specifically, the angular domain constraint weight for the non-target region is greater than that for the transition region, and the angular domain constraint weight for the transition region is greater than that for the target detection region. Sidelobe energy constraints are generated based on the off-axis energy distribution and corresponding angular domain constraint weights within each region.

[0031] A joint adjustment target is constructed based on main lobe morphology error, side lobe energy constraint, phase smoothing constraint, and amplitude equalization constraint. The amplitude weights and phase corrections of each array element are adjusted iteratively until the joint adjustment target meets the preset convergence condition. After adjusting the amplitude weights and phase corrections, the basic scanning phase of each array element is superimposed with the phase correction to obtain the final control phase of each element. Then, the amplitude weights and final control phases of each element are loaded into a two-dimensional silicon-based optical phased array to control the output light intensity and output phase of each element.

[0032] Each array element outputs an optical signal according to its corresponding amplitude weight and final control phase. The output optical signals of each array element are coherently superimposed in the angular domain corresponding to the target scanning direction to form a shaped beam. The shaped beam serves as the transmission beam of the wind-measuring radar, used to emit a detection optical signal in the target detection direction.

[0033] Reference Figure 2 Furthermore, in step S2, the step of generating an initial set of array element positions that satisfies the minimum spacing constraint within the deployable area of ​​the chip includes: Candidate deployment locations are determined according to a preset sparse occupancy ratio; Calculate the spacing between the candidate deployment positions and the positions of the already added array elements in sequence; When the spacing is not less than the minimum spacing of the array elements, the candidate placement position is retained; When the number of array elements reaches the preset number, the initial array element position set is generated.

[0034] In step S2, the step of constructing a set of difference vectors based on the positional difference between any two array elements includes: Select any two different array elements; Calculate the lateral and longitudinal position differences between two different array elements; Combine the lateral position difference and the longitudinal position difference into a difference vector; By traversing all different pairs of array elements, we obtain the set of difference vectors.

[0035] Specifically, firstly, based on the deployable area of ​​the chip... The geometric dimensions are used to establish candidate placement meshes. The chip's placement area... Preferably, the region is rectangular, and its horizontal length is denoted as . The longitudinal length is denoted as In this plan, The preferred diameter is 8mm to 20mm. The preferred size is 8mm to 20mm. The transverse and longitudinal step sizes of the candidate grid layout are denoted as follows: and The two are preferably set to the minimum spacing between array elements. The number of candidate deployment locations is 0.5 to 1 times that of the previous one, to ensure that the number of candidate deployment locations meets the requirements for subsequent screening.

[0036] Candidate deployment locations can be represented as: ; in, Indicates the first line, number The candidate deployment positions corresponding to the column; Indicates the horizontal grid step size; Indicates the vertical grid step size; and These represent the serial numbers of the candidate deployment positions in the horizontal and vertical directions, respectively.

[0037] The preset sparse duty cycle is denoted as This represents the ratio between the actual number of array elements selected and the total number of candidate deployment locations. Based on the number of array elements... and preset sparse duty cycle Determine the total number of candidate deployment locations. ,satisfy: ;in, Indicates the total number of candidate deployment locations; Indicates the number of array elements; This indicates the preset sparse duty cycle.

[0038] After the candidate placement positions are determined, they are added to the initial element position set in a preset order. The preset order can be sorted by horizontal and vertical coordinates from smallest to largest, or by expanding outwards from the chip center. When adding a candidate placement position, the Euclidean distance between that candidate placement position and the currently added element positions is calculated. ; in, Indicates the current candidate deployment position and the first The distance between the positions of the elements that have been added to the array; The coordinates of the current candidate deployment location; This represents the coordinates of the kth element that has been added to the array.

[0039] When the following conditions are met: , At that time, the candidate deployment location is retained. This indicates the number of elements currently added to the array; This represents the minimum spacing between array elements. The initial array element position set is generated when the number of array elements in the initial set reaches the preset number N. The initial array element position set is represented as: ; in, Represents the initial set of array element positions; Indicates the first The position vectors of each array element.

[0040] After generating the initial set of array element positions, construct a difference vector for any two distinct array elements in the set. Each array element and the first The difference vector between the array elements is represented as: ; in: ; .

[0041] By traversing all satisfied The pairs of array elements form a set of difference vectors: ; in, This represents the set of difference vectors. The array elements, and the difference vector set contains... An ordered difference vector.

[0042] Each difference vector in the difference vector set corresponds to a set of relative positional relationships of array elements. Subsequent steps involve statistically analyzing the distribution of differences at different positions based on the difference vector set to identify repetitive spacing patterns in the array element positions.

[0043] Through the above steps, an initial set of array element positions that satisfy the minimum spacing constraint of array elements is first formed in the chip's deployable area. Then, the relative positional relationship between array elements is converted into a set of differential vectors, providing input data for subsequent differential density distribution generation and local periodic evaluation, thereby providing a basis for adjusting the spatial distribution of the wind measurement radar's transmitted beam.

[0044] Furthermore, in step S3, the step of evaluating the local periodicity of the initial array element position set based on the difference vector aggregation region includes: Multiple differential sampling positions are set within the differential plane; Calculate the degree of overlap of the difference vectors at each difference sampling position; Regions with an overlap exceeding a preset density threshold are defined as differential vector aggregation regions; Local periodic evaluation results are generated based on the number and concentration of the difference vector cluster regions.

[0045] Specifically, the difference plane adopts a two-dimensional coordinate system consistent with the chip plane. Its horizontal axis represents the lateral positional difference of the difference vectors, and its vertical axis represents the vertical positional difference of the difference vectors. The range of values ​​for the difference plane is determined by the maximum lateral positional difference and the maximum vertical positional difference of all difference vectors.

[0046] Multiple differential sampling positions are set at fixed intervals within the differential plane. Each differential sampling position is represented as: ;in, Indicates the first One differential sampling position; Indicates the first The coordinate values ​​of each differential sampling position on the horizontal coordinate axis; Indicates the first The coordinate values ​​of each differential sampling position on the vertical coordinate axis; This indicates the total number of differential sampling locations.

[0047] For each differential sampling location, the distribution of the differential vector within its neighborhood is statistically analyzed. The neighborhood radius is denoted as... When the distance between a certain difference vector and the difference sampling position is no greater than At this time, the difference vector is included in the overlap of the corresponding difference sampling position. The difference density at the difference sampling position is expressed as: ; in, Indicates the first Differential density at each differential sampling location; This represents the total number of difference vectors; Indicates the first One difference vector; This represents the smoothing parameter.

[0048] In some implementations, the degree of overlap can also be determined by neighborhood counting, that is, by counting the radius of the neighborhood. The number of difference vectors within the sampled area is calculated, and this number is used as the difference density value. After calculating the difference density for all difference sampling locations, the difference density distribution is obtained. The maximum value in the difference density distribution is denoted as: ; in, This represents the maximum difference density value in the difference density distribution.

[0049] The preset density threshold is denoted as The preferred method is to determine the value using a proportional form of the maximum difference density value: ;in, This represents the threshold scaling factor. In this scheme, Preferably, it is 0.60 to 0.95. When the following conditions are met: When the corresponding differential sampling position is determined as the high-density sampling position, adjacent high-density sampling positions are merged into a differential vector aggregation region.

[0050] The area of ​​the region where the c-th difference vector clusters is denoted as . The average difference density within the region is denoted as ,in, , This represents the number of regions where the difference vectors cluster. The local periodicity evaluation value is expressed as: ; in, This represents a local periodic evaluation value; This represents the area of ​​the region where the c-th difference vector is clustered. Indicates the first The average difference density of the difference vector clustering regions; C represents the number of difference vector clustering regions.

[0051] When the local periodic evaluation value Greater than the preset local periodicity threshold When the current initial array element position set is determined to have obvious local periodicity; when the local periodicity evaluation value Not greater than the preset local periodicity threshold At that time, it is determined that the current initial set of array element positions meets the requirements for subsequent position adjustments. A preset local periodic threshold is used. The optimal value is determined based on historical design data, and the preferred value range is 0.8 to 1.2 times the average evaluation value of all candidate arrays. The center position of the differential vector aggregation region can also be obtained by weighted averaging of the differential sampling positions within the region. This center position is used to subsequently determine the corresponding target array element and the direction of position adjustment.

[0052] Through the above processing, the differential vector set is converted into a differential density distribution, and local periodic evaluation results are generated based on the number, area and average differential density of the differential vector clustering region. This quantifies the distribution of the repetitive position difference between array elements into evaluation parameters that can be used for subsequent position adjustment, providing a basis for reducing the fixed-direction off-axis energy accumulation in the wind measurement radar beam.

[0053] Furthermore, in step S4, the step of adjusting the position set of the initial array elements according to local periodicity includes: Determine the target array elements of the corresponding difference vector clustering region; The perturbation is adjusted according to the degree of contribution of the target array element to the local periodicity; Regenerate the difference density distribution; When the differential density distribution meets the preset uniformity requirement, a sparse non-periodic array element position set is obtained.

[0054] In step S4, the steps of performing minimum spacing constraints on array elements and chip deployable area constraints during the position adjustment process include: Determine whether the array elements after position adjustment are located within the chip's deployable area; Determine whether the spacing between the array elements after the position adjustment is not less than the minimum spacing between array elements; When all of the above conditions are met, the positions of the array elements after the position adjustment are retained. Otherwise, rollback or re-disturbance will be performed.

[0055] Specifically, after the difference vector clustering region is determined, the corresponding array element pairs are first determined by reverse engineering based on the difference vectors contained within the clustering region. Let the c-th difference vector clustering region be... When the difference vector Falling into the region of difference vector clustering At that time, the first Each array element and the first Each element is determined as the target element corresponding to the region where the difference vector clusters. The set of target elements is represented as: ; in, Represents the target array element set; Indicates the array element number; and Indicates the indices of the two distinct array elements that form the difference vector; Indicates the first Individual elements and the first The difference vector between each array element; Indicates the first A region where difference vectors cluster.

[0056] For the nth target element in the target element set, count the number of times the target element participates in forming the difference vector within the difference vector cluster region, and use this number as the contribution of the target element to the local periodicity. The contribution is expressed as: ; in, Indicates the first The degree of contribution of each target array element to local periodicity; This indicates the number of regions where the difference vectors cluster. Indicates the number of array elements; This indicates an indicator function that takes the value 1 when the condition within the parentheses is true, and 0 otherwise.

[0057] According to the degree of contribution The target array elements are sorted from largest to smallest, with priority given to perturbating and adjusting the elements that contribute the most. In this scheme, the target array elements with the highest contribution (top 10%–30%) are selected for position adjustment in each iteration.

[0058] The perturbation direction of the target array element's position is determined based on the center direction of the difference vector aggregation region in which the target array element participates. Let the target array element... The corresponding direction of the combined disturbance is The position of the target element is determined by the deviation direction between the center position of the region where the target element participates in the difference vector aggregation and the corresponding difference vector. ; in, Indicates the first During the nth iteration The position of each target array element; Indicates the position of the array element after the perturbation adjustment; Indicates the first The position perturbation step size for the next iteration; Indicates the direction of the combined disturbance For target array elements where the direction of the combined perturbation is difficult to determine, a candidate perturbation method is used to perform position adjustment. This involves setting multiple candidate perturbation positions around the current position of the target array element, calculating the change in the differential density distribution corresponding to each candidate perturbation position, and selecting the candidate perturbation position that reduces the local periodicity evaluation value as the adjusted position. After position adjustment, a chip deployment area constraint check is performed on the adjusted array element position. If the adjusted array element position satisfies: If so, it is determined that it is located within the chip's deployable area. This indicates the area where the chip can be deployed.

[0059] Simultaneously, the adjusted array element positions are checked for minimum element spacing constraints. If the adjusted array element positions satisfy: ; Then it is determined that it satisfies the minimum spacing constraint of the array elements. Among them, Indicates the first The array element in the first The position at the next iteration; This represents the minimum spacing between array elements.

[0060] If the adjusted element position satisfies both the chip's deployable area constraint and the minimum element spacing constraint, the adjusted element position is retained. If the adjusted element position does not satisfy either constraint, the current position adjustment is cancelled, and perturbation adjustment is re-executed according to the candidate perturbation positions. If all candidate perturbation positions do not satisfy the constraints, the element's original position in this iteration is maintained, and the process moves to the next target element's position adjustment.

[0061] After completing one round of target element position adjustments, the difference vector set is reconstructed, and the difference density distribution is regenerated. The regenerated difference density distribution is used to calculate the updated local periodicity evaluation value. Let the th... The local periodicity evaluation value corresponding to the next iteration is , No. The local periodicity evaluation value corresponding to the next iteration is When the following conditions are met: If the position is adjusted, retain the position adjustment result of this round; otherwise, restore the position to the position state before this round of adjustment, or reduce the position disturbance step size and re-execute the position adjustment.

[0062] When the differential density distribution meets the preset uniformity requirement, the current set of array element positions is taken as the set of sparse non-periodic array element positions, represented as: ; in, Represents the set of positions of sparse non-periodic array elements; This represents the position vector of the nth array element after position adjustment.

[0063] Through the above processing, the array element position adjustment uses the differential vector aggregation region as input and the contribution of the target array element to the local periodicity as the adjustment basis. After each adjustment, checks are performed on the chip deployable area constraint and the minimum array element spacing constraint, thereby forming a sparse aperiodic array element position set that meets the manufacturing and deployment conditions. When this sparse aperiodic array element position set is used for subsequent phase control and amplitude control, it can reduce the fixed-direction off-axis energy concentration caused by the repetitive array element spacing, and reduce the non-target direction energy output in the wind measurement radar's transmitted beam.

[0064] Reference Figure 3 Furthermore, in step S5, the step of calculating the basic scanning phase of each array element based on the sparse aperiodic array element position set includes: Determine the center position of the target beam; Generate the target beam shape based on the preset main lobe shape parameters; The phase compensation relationship is determined based on the position of each array element; The basic scanning phase of each array element is calculated based on the phase compensation relationship.

[0065] Specifically, the target scanning direction is determined by the pitch angle. and azimuth Indicated. Based on the target scanning direction and operating wavelength. This converts the target scanning direction into the spatial frequency component corresponding to the center position of the target beam. The center position of the target beam is represented as a coordinate point in a two-dimensional angular domain. The calculation formula is as follows: , ; in, The coordinates representing the center position of the target beam along the first spatial frequency direction; The coordinate value representing the center position of the target beam in the direction of the second spatial frequency; Indicates the operating wavelength; The pitch angle indicating the target scanning direction; The azimuth angle indicates the direction of target scanning.

[0066] After determining the center position of the target beam, the target beam shape is generated according to preset main lobe shape parameters. The preset main lobe shape parameters include the main lobe width parameter in the first direction. Second direction main lobe width parameters The target beam shape is represented as follows: ; in, Indicates the shape of the target beam; and Represents the spatial frequency coordinates in a two-dimensional angular domain; This represents the main lobe width parameter in the first direction; This represents the main lobe width parameter in the second direction. When... At that time, the target beam shape corresponds to a circular main lobe; when At that time, the target beam shape corresponds to an elliptical main lobe.

[0067] In the vertical detection mode of the wind-measuring radar, the preferred setting is... This ensures that the beam cross-section remains axially symmetrical in the target direction. In tilt scan mode, the angular resolution requirements in different directions can be set separately. and .

[0068] After the target beam shape is determined, the phase compensation relationship is calculated based on the positions of each element in the sparse aperiodic array element set. Let the position of the nth element be: ;in, Indicates the first The position vectors of each array element in the sparse nonperiodic array element position set; Indicates the horizontal coordinate value; yn This represents the longitudinal coordinate value. For the target beam center position... , No. The phase compensation required for each element is determined by the projection relationship between the element position and the target beam center position. The basic scanning phase is expressed as: ; in, Indicates the first The basic scanning phase of each array element; and These represent the spatial frequency coordinates of the target beam's center position; and These represent the position coordinates of the nth array element. The aforementioned basic scanning phase ensures that the phase difference between each array element at the center of the target beam cancels out the propagation path difference, thereby enabling the output optical signals of each array element to satisfy the coherent superposition condition in the target scanning direction.

[0069] Since the phase modulation unit typically employs a periodic control structure, the basic scanning phase can be limited to one phase period during actual loading. The normalized basic scanning phase is expressed as: ; in, This represents the normalized base scan phase. This indicates the modulo operation.

[0070] In multi-target scanning scenarios, different target scanning directions can be set sequentially according to a preset scanning sequence, and the corresponding basic scanning phase can be calculated for each. During the switching of each scanning direction, only the basic scanning phase is updated, while the array element positions remain unchanged. The target beam shape serves as a reference template for subsequent joint adjustment of amplitude weights and phase corrections, and the basic scanning phase serves as the initial value for phase control. Subsequent steps superimpose phase corrections on the basic scanning phase to further correct the main lobe shape and side lobe distribution.

[0071] Through the above processing, the target scanning direction is converted into the target beam center position, and the target beam shape is generated according to the preset main lobe shape parameters. Then, the basic scanning phase of each array element is calculated according to the sparse non-periodic array element position set, providing target distribution and initial phase data for the subsequent joint adjustment of amplitude weight and phase correction, so that the wind measurement radar emitted beam forms a preset main lobe energy distribution in the target detection direction.

[0072] Furthermore, in step S6, the step of jointly adjusting the amplitude weights and phase corrections of each array element includes: Calculate the actual far-field light intensity distribution; divide the main lobe region and side lobe regions; Determine the sidelobe energy constraints, main lobe morphology errors, phase smoothing constraints, and amplitude equalization constraints; The amplitude weight and phase correction are iteratively adjusted based on the main lobe morphology error, side lobe energy constraints, phase smoothing constraints, and amplitude equalization constraints.

[0073] The steps to determine the sidelobe energy constraint include: The angular region outside the main lobe region is divided into the target detection region, the transition region, and the non-target region; Set corresponding corner domain constraint weights for the target detection region, transition region, and non-target region respectively; Make the corner constraint weight of the non-target region greater than the corner constraint weight of the transition region, and make the corner constraint weight of the transition region greater than the corner constraint weight of the target detection region; Statistical analysis of off-axis energy distribution within each region; Sidelobe energy constraints are generated based on the off-axis energy distribution and corresponding angular domain constraint weights within each region.

[0074] In step S6, the step of forming a shaped beam based on the amplitude weight and the final control phase includes: The basic scanning phase of each array element is superimposed with the phase correction amount to obtain the final control phase; The amplitude weights and final control phase are loaded into a two-dimensional silicon-based optical phased array; Controlling the coherent superposition of each array element to form a shaped beam.

[0075] Specifically, after the set of sparse aperiodic array element positions is fixed, the amplitude weight and phase correction of each element are used as parameters to be adjusted. The amplitude weights of each array element are denoted as: The phase correction amount is denoted as Based on the sparse aperiodic array element location set, amplitude weights, and phase control parameters, the array factor in the two-dimensional angular domain is calculated: ; in, Represents coordinates in a two-dimensional angular domain Array factor at the location; Indicates the number of array elements; Indicates the first The amplitude weight of each array element; and They represent the first The horizontal and vertical coordinates of each array element in the sparse nonperiodic array element position set; Indicates the first The final control phase of each array element; It represents the imaginary unit.

[0076] The actual far-field light intensity distribution is calculated based on the array factor and then normalized. ; in, This represents the normalized actual far-field light intensity distribution; Represents the set of sampling points in a two-dimensional corner domain; It represents the maximum array factor intensity in the set of sampling points in the two-dimensional angular domain.

[0077] Based on the center position of the target beam Divide the lobe into main lobe and lateral lobe regions. The main lobe region is denoted as... It is composed of sampling points around the center of the target beam. The sidelobe region is denoted as... This refers to the region outside the main lobe region within the set of two-dimensional angular domain sampling points. The main lobe morphology error is determined based on the difference between the target beam shape and the actual far-field intensity distribution within the main lobe region. ; in, This indicates an error in the shape of the main lobe. Indicates the main lobe region; This represents the actual far-field light intensity distribution; Indicates the shape of the target beam.

[0078] The side lobe region is: ;in, Indicates the side lobe region; Represents the set of sampling points in a two-dimensional corner domain; This represents the main lobe region. When determining the sidelobe energy constraints, the sidelobe region is... Divided into target detection areas Transitional area Non-target areas Target detection area The angular region that is close to the main lobe region but still falls within the receiving field of view of the wind-measuring radar; the transition region. The angular region between the target detection area and the non-target area; the non-target area This refers to the angular domain outside the receiving field of view of the wind-measuring radar or corresponding to the preset suppression direction.

[0079] The target detection region, transition region, and non-target region correspond to the angular domain constraint weights, respectively. , and And satisfy: ;in, The corner domain constraint weights represent the target detection region; Indicates the corner domain constraint weights of the transition region; The corner domain constraint weights represent the non-target region. The sidelobe energy constraint is expressed as: ; in, This indicates sidelobe energy constraint; Indicates the target detection area; Indicates a transition region; Indicates a non-target area; This represents the actual far-field light intensity distribution.

[0080] Phase smoothing constraints are determined based on the difference in phase correction between adjacent array elements. The set of adjacent array element pairs is denoted as... This can be determined based on the physical distance between array elements. In this scheme, when the distance between two array elements is no greater than... When this occurs, they are identified as a pair of adjacent array elements. The phase smoothing constraint is expressed as: ; in, This indicates a phase smoothing constraint; Represents the set of adjacent array element pairs; and They represent the first Each array element and the first The phase correction amount for each array element. The amplitude equalization constraint is determined based on the deviation between the amplitude weight of each array element and the average amplitude weight. The average amplitude weight is expressed as: ;in, Indicates the average magnitude weight; Indicates the first The amplitude weight of each array element; Indicates the number of array elements.

[0081] The amplitude equalization constraint is expressed as: ;in, This represents the amplitude equalization constraint. A joint adjustment objective is constructed based on the main lobe morphology error, side lobe energy constraint, phase smoothing constraint, and amplitude equalization constraint: ; in, This indicates a joint adjustment of objectives; Indicates the weight of the main lobe morphology error; Indicates the sidelobe energy constraint weight; Indicates the phase smoothing constraint weights; This represents the magnitude balance constraint weight. In this scheme, Preferably 1 to 10, The preferred values ​​are 1 to 20. Preferably, it is 0.01 to 1. The preferred value is 0.01 to 1.

[0082] Amplitude weighting and phase correction When making iterative adjustments, reduce the joint adjustment target. To adjust the criteria, the actual far-field light intensity distribution, main lobe shape error, side lobe energy constraints, phase smoothing constraints, and amplitude equalization constraints are recalculated after each iteration.

[0083] In this scheme, the initial values ​​of the amplitude weights are preferably set to the same value, and the initial value of the phase correction is preferably set to 0. The change in amplitude weights in each iteration is preferably no greater than 0.05, and the change in phase correction in each iteration is preferably no greater than 0.1 rad. The number of iterations is preferably 50 to 500, or iteration is stopped when the change in the joint adjustment target is less than a preset convergence threshold in several consecutive iterations. The preset convergence threshold is preferably 0.1% to 1% of the initial joint adjustment target.

[0084] After completing the iterative adjustments, the base scan phase and the phase correction amount are superimposed to obtain the final control phase: ;in, Indicates the first The final control phase of each array element; Indicates the first The basic scanning phase of each array element; Indicates the first Phase correction of each array element.

[0085] Before being loaded onto a two-dimensional silicon-based optical phased array, the final control phase is subjected to phase period normalization: ;in, This represents the final control phase after normalization; This indicates the modulo operation.

[0086] The amplitude control unit of a two-dimensional silicon-based optical phased array is based on amplitude weights. Control the first The output light intensity of each array element is determined by the phase modulation unit based on the normalized final control phase. Control the first The output phase of each array element. The output optical signals of each array element are coherently superimposed in the angular domain corresponding to the target scanning direction to form a shaped beam.

[0087] Through the above processing, the target detection area, transition area and non-target area corresponding to the wind measurement radar are included in the sidelobe energy constraint. The main lobe shape error, sidelobe energy constraint, phase smoothing constraint and amplitude equalization constraint are used together to adjust the amplitude weight and phase correction amount. This makes the shaped beam meet the preset main lobe shape in the target scanning direction and reduces the off-axis energy output in the non-target area, thereby reducing the influence of stray echoes in the non-target direction during the wind measurement radar transmission process.

[0088] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for beam shaping of a two-dimensional silicon-based optical phased array based on a sparse non-periodic array, characterized in that, Includes the following steps: S1. Obtain the number of array elements, chip deployment area, minimum array element spacing and target scanning direction of the two-dimensional silicon-based optical phased array, and establish a two-dimensional position model of each array element in the chip plane. S2. Generate an initial set of array element positions that satisfy the minimum spacing constraint of array elements within the deployable area of ​​the chip, and construct a set of difference vectors based on the position difference between any two array elements. S3. Generate a differential density distribution based on the differential vector set, identify differential vector clustering regions, and evaluate the local periodicity of the initial array element position set based on the differential vector clustering regions; S4. Adjust the position set of the initial array element positions according to the local periodicity, and perform array element minimum spacing constraint and chip deployable area constraint check during the position adjustment process to obtain a sparse non-periodic array element position set. S5. Construct the target beam shape according to the target scanning direction, and calculate the basic scanning phase of each element according to the sparse non-periodic element position set; S6. Under the condition that the positions of the sparse non-periodic array elements are fixed, the amplitude weight and phase correction of each array element are jointly adjusted according to the difference between the target beam shape and the actual far-field light intensity distribution, the off-axis energy distribution outside the main lobe region, the smoothness of the phase change between adjacent array elements, and the amplitude balance between each array element. The basic scanning phase and the phase correction are superimposed to obtain the final control phase, so as to form a shaped beam according to the amplitude weight and the final control phase.

2. The beam shaping method for a two-dimensional silicon-based optical phased array based on a sparse non-periodic array according to claim 1, characterized in that, In step S2, the step of generating an initial set of array element positions that satisfies the minimum spacing constraint within the deployable area of ​​the chip includes: Candidate deployment locations are determined according to a preset sparse occupancy ratio; Calculate the spacing between the candidate deployment positions and the positions of the already added array elements in sequence; When all the spacings are not less than the minimum spacing of the array elements, the candidate placement position is retained; When the number of array elements reaches the preset number, the initial array element position set is generated.

3. The beam shaping method for a two-dimensional silicon-based optical phased array based on a sparse non-periodic array according to claim 1, characterized in that, In step S2, the step of constructing a set of difference vectors based on the positional difference between any two array elements includes: Select any two different array elements; Calculate the lateral and longitudinal position differences between two different array elements; The lateral position difference and the longitudinal position difference are combined into a difference vector; By traversing all different array element pairs, the set of difference vectors is obtained.

4. The beam shaping method for a two-dimensional silicon-based optical phased array based on a sparse non-periodic array according to claim 1, characterized in that, In step S3, the step of evaluating the local periodicity of the initial array element position set based on the difference vector aggregation region includes: Multiple differential sampling positions are set within the differential plane; Calculate the degree of overlap of the difference vectors at each difference sampling position; Regions with an overlap exceeding a preset density threshold are defined as differential vector aggregation regions; Local periodic evaluation results are generated based on the number and concentration of the differential vector clustering regions.

5. The beam shaping method for a two-dimensional silicon-based optical phased array based on a sparse non-periodic array according to claim 1, characterized in that, In step S4, the step of adjusting the position set of the initial array elements according to the local periodicity includes: Determine the target array elements of the corresponding difference vector clustering region; The perturbation is adjusted according to the degree of contribution of the target array element to the local periodicity; Regenerate the difference density distribution; When the differential density distribution meets the preset uniformity requirement, the sparse non-periodic array element position set is obtained.

6. The beam shaping method for a two-dimensional silicon-based optical phased array based on a sparse non-periodic array according to claim 1, characterized in that, In step S4, the step of performing minimum spacing constraints on array elements and chip deployable area constraints during the position adjustment process includes: Determine whether the array element after position adjustment is located within the deployable area of ​​the chip; Determine whether the spacing between the array element after position adjustment and other array elements is not less than the minimum spacing between array elements; When all of the above conditions are met, the positions of the array elements after the position adjustment are retained. Otherwise, rollback or re-disturbance will be performed.

7. The beam shaping method for a two-dimensional silicon-based optical phased array based on a sparse non-periodic array according to claim 1, characterized in that, In step S5, the step of calculating the basic scanning phase of each array element based on the sparse aperiodic array element position set includes: Determine the center position of the target beam; The target beam shape is generated according to the preset main lobe shape parameters; The phase compensation relationship is determined based on the position of each array element; The basic scanning phase of each array element is calculated based on the phase compensation relationship.

8. The beam shaping method for a two-dimensional silicon-based optical phased array based on a sparse non-periodic array according to claim 1, characterized in that, In step S6, the step of jointly adjusting the amplitude weights and phase corrections of each array element includes: Calculate the actual far-field light intensity distribution; divide the main lobe region and side lobe regions; Determine the sidelobe energy constraints, main lobe morphology errors, phase smoothing constraints, and amplitude equalization constraints; The amplitude weight and the phase correction amount are iteratively adjusted based on the main lobe morphology error, the side lobe energy constraint, the phase smoothing constraint, and the amplitude equalization constraint.

9. The beam shaping method for a two-dimensional silicon-based optical phased array based on a sparse non-periodic array according to claim 8, characterized in that, The steps for determining the sidelobe energy constraint include: The angular region outside the main lobe region is divided into the target detection region, the transition region, and the non-target region; Set corresponding corner domain constraint weights for the target detection region, transition region, and non-target region respectively; Make the corner constraint weight of the non-target region greater than the corner constraint weight of the transition region, and make the corner constraint weight of the transition region greater than the corner constraint weight of the target detection region; Statistical analysis of off-axis energy distribution within each region; The sidelobe energy constraints are generated based on the off-axis energy distribution in each region and the corresponding angular domain constraint weights.

10. The beam shaping method for a two-dimensional silicon-based optical phased array based on a sparse non-periodic array according to claim 1, characterized in that, In step S6, the step of forming a shaped beam based on the amplitude weight and the final control phase includes: The basic scanning phase of each array element is superimposed with the phase correction amount to obtain the final control phase; The amplitude weights and the final control phase are loaded into a two-dimensional silicon-based optical phased array; The shaping beam is formed by coherently superimposing the array elements.

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