A laser coherence regulation device and method for a multi-channel silicon-based optical phased array system

Abstract

The application discloses a laser coherence regulation device and method for a multi-channel silicon-based optical phased array system and relates to the field of coherent laser radars. Laser signal is modulated to meet a statistical model of laser phase noise sequence by an electro-optic modulator, a balanced photodetector output signal and a camera light spot are used to correct modulation parameters, a closed-loop control regulation result is adopted, and non-uniform interference fringes are effectively suppressed. In a two-channel silicon-based optical phased array system, the light spot uniformity can be improved by 25.5%. The application is specially designed for the multi-channel silicon-based optical phased array system and has the characteristics of high simulation accuracy, rapid response and low manufacturing cost.

Description

Technical Field

[0001] This invention relates to the field of coherent lidar, and more particularly to a laser coherence modulation device and method for multi-channel silicon-based optical phased array systems. Background Technology

[0002] Silicon-based optical phased arrays (OPA) are a novel beam control scheme based on silicon-based optoelectronic integration technology. Utilizing thermo-optic or electro-optic effects, the refractive index of each channel in the waveguide array is precisely controlled by an applied voltage, thereby altering the phase difference between beams. When the beams interfere and superimpose in the far field, constructive interference in a specific direction is achieved, forming a high-energy main lobe beam. Compared to traditional mechanical or microelectromechanical systems (MEMS) scanning schemes, silicon-based OPAs eliminate macroscopic moving parts, offering significant advantages such as small size, extremely high scanning speed (reaching MHz or even GHz levels), long lifespan, and strong resistance to vibration and shock. Crucially, when combined with coherent lidar technologies such as frequency-modulated continuous wave (FMCW), OPAs not only drastically reduce system size but also provide extremely high ranging and velocity sensitivity and strong resistance to ambient light interference. This represents a core technological route for the future low-cost, high-performance mass production of all-solid-state lidar.

[0003] In the evolution of silicon-based OPA systems, increasing the number of waveguide antenna array elements to improve the overall radar performance is an inevitable path. Increasing the number of channels significantly narrows the beam divergence angle and improves laser energy concentration, enabling longer detection ranges and higher spatial resolution. Secondly, the large number of channels provides ample freedom for complex beamforming, adapting to various complex application scenarios.

[0004] However, when using a narrow-linewidth laser as input to a multi-channel OPA, the close proximity of the center frequencies of the optical signals in each channel will create stable standing-wave interference fringes, leading to strong image speckle effects at the receiver and significantly degrading image quality and detection sensitivity. Secondly, in links requiring beam coupling into optical fibers or other waveguides, this mode mismatch causes severe coupling losses, drastically reducing the system's effective optical power budget. Furthermore, in scenarios requiring high-precision acquisition, pointing, and tracking (ATP), such as optical communication or space laser power transfer, fluctuations in the intensity of the interference spot can cause centroid drift, severely interfering with the readings of position-sensitive devices (such as four-quadrant detectors), leading to misjudgments of the spot position by the ATP system and significantly reducing locking accuracy and system alignment margin.

[0005] To address the aforementioned multi-channel beam interference problem, several mainstream suppression schemes have been attempted in the industry, but each has significant limitations in application. One approach is based on improvements to the hardware architecture. For example, the reference (Ma Pengfei, Yu Lei, Wang Zheng, Wang Pengfei, Zhang Yejin, Pan Jiaoqing. 128-channel optical phased array based on SiN planar waveguide grating [J]. Laser Technology, 2024, 48(6): 832-837.) employs a sparse array design or non-uniform waveguide spacing (such as waveguide superlattice structure) to disrupt the fixed phase correlation between channels and smooth the far-field beam. However, this approach often sacrifices the energy concentration of the main lobe and may even introduce grating lobes. Secondly, there is software algorithm compensation. For example, the reference (Wei Tianhao, Zhao Di, Yan Kun, et al. Optimization of optical phased array based on particle swarm optimization algorithm [J]. Optical Technology, 2025(3).) uses particle swarm optimization algorithm combined with closed-loop feedback system to dynamically fine-tune the driving voltage of each channel to find the optimal phase matching point. However, this requires high-precision far-field monitoring equipment, and the algorithm has a long convergence time, which cannot adapt to the high-speed dynamic change of the channel environment. In addition, the patent (CN103532620A) discloses a system and method for controlling the coherence effect in a narrow linewidth light source, but its control accuracy needs to be verified, and there are problems such as slow response speed and nonlinear disturbance. In addition, using independent laser drive will also greatly increase hardware cost and increase the difficulty of engineering integration.

[0006] In summary, existing technologies have failed to fundamentally solve the extreme sensitivity of multi-channel coherent systems to phase errors. There is an urgent need for an innovative device and method that can actively control coherent characteristics at the light source level, respond quickly, and without sacrificing the main lobe performance. Summary of the Invention

[0007] The purpose of this invention is to provide a laser coherence modulation device and method for multi-channel silicon-based optical phased array systems.

[0008] The objective of this invention can be achieved through the following technical solution: a laser coherence modulation device for a multi-channel silicon-based optical phased array system, the device comprising:

[0009] The first fiber beam splitter has its input end connected to the output end of the laser. The first fiber beam splitter has three output ends: the first output end is connected to the input end of the fiber coupler, the second output end is connected to the input end of the second silicon-based optical phased array, and the third output end is connected to the input end of the electro-optic modulator.

[0010] The second fiber beam splitter has an input end connected to the output end of an electro-optic modulator. The second fiber beam splitter has two output ends. The first output end outputs a laser signal through the first silicon-based optical phased array, which is combined with the laser signal output by the second silicon-based optical phased array on the target surface of the camera. The second output end is connected to the input end of a fiber coupler, and the output end of the fiber coupler is connected to the input end of a balanced photodetector.

[0011] The signal acquisition and processing module extracts the phase of the monitoring signal output by the balanced photodetector and the light spot acquired by the camera, and corrects the parameters in the signal modulation module.

[0012] The signal modulation module generates a laser phase noise sequence and modulates the laser signal using an electro-optic modulator.

[0013] Furthermore, the output terminal of the signal modulation module is connected to the input terminal of the electro-optic modulator; the input terminal of the signal acquisition and processing module is connected to the output terminal of the camera and the output terminal of the balanced photodetector, and the output terminal of the signal acquisition and processing module is connected to the input terminal of the signal modulation module.

[0014] Furthermore, the performance parameters of the first silicon-based optical phased array are consistent with those of the second silicon-based optical phased array.

[0015] Furthermore, the first fiber beam splitter splits the light into three beams; one beam is input to an electro-optic modulator to modulate the required phase noise for the first silicon-based optical phased array to control coherence; the second beam is input to the second silicon-based optical phased array, and the output beam serves as the reference light for the camera to monitor interference effects; the third beam is input to a fiber coupler as the local oscillator light for coherent detection.

[0016] Furthermore, the second fiber beam splitter inputs the signal light to the fiber coupler, where it is coherently mixed with the local oscillator and then received by a balanced photodetector to monitor the coherence modulation effect in real time.

[0017] On the other hand, the present invention also provides a method for controlling the laser coherence of a multi-channel silicon-based optical phased array system, the steps of which are as follows:

[0018] S1: The signal modulation module generates a laser phase noise sequence, which is then used to modulate the laser signal by the electro-optic modulator;

[0019] S2: The signal acquisition and processing module extracts the phase of the monitoring signal output by the balanced photodetector and corrects the parameters in the signal modulation module according to the error amount;

[0020] S3: The signal acquisition and processing module extracts the light spot acquired by the camera and corrects the parameters in the signal modulation module again based on the light spot uniformity error.

[0021] S4: When the uniformity of the light spot acquired by the camera meets the set value, the laser coherence modulation is completed, and the closed-loop control result of the output signal modulation module is output.

[0022] Furthermore, the signal modulation module is configured to perform the following steps:

[0023] (1) Generate a white noise time-domain sequence, and perform spectral filtering based on the phase noise power spectral index and phase noise intensity coefficient, and then convert it into a time-domain sequence;

[0024] (2) Set the initial value of the quadratic proportional coefficient, calculate the initial time-domain noise amplitude, and calculate the initial phase noise sequence;

[0025] (3) Perform power spectral density analysis on the initial phase noise sequence to determine the measured values ​​of the phase noise power spectral index and the phase noise intensity coefficient;

[0026] (4) If the error between the measured value of the phase noise power spectrum index and the target value is greater than the tolerance, the phase noise power spectrum index is dynamically adjusted within the preset search interval with the aim of reducing the error, and the spectrum filtering process of step (1) is executed again until the error is less than the tolerance or the number of iterations is sufficient.

[0027] (5) If the error between the measured value of the phase noise intensity coefficient and the target value is greater than the tolerance, then with the aim of reducing the error, the second proportional coefficient is dynamically adjusted within the preset search interval, and step (2) is executed again until the error is less than the tolerance or the number of iterations is sufficient.

[0028] (6) Output the final phase noise sequence generated after iterative optimization.

[0029] Furthermore, step (1) is as follows:

[0030] (1.1) Generate a white noise time-domain sequence, perform a discrete Fourier transform on it, and obtain a frequency-domain sequence;

[0031] (1.2) The phase noise power spectral index is obtained based on the phase noise power spectral density and the phase noise intensity coefficient, and the frequency domain sequence is spectral filtered based on the phase noise power spectral index;

[0032] (1.3) Perform discrete inverse Fourier transform on the frequency domain signal after spectral filtering to obtain the time domain sequence.

[0033] Furthermore, the signal acquisition and processing module is configured to perform the following steps:

[0034] 1) Extract the phase of the output signal of the balanced photodetector, calculate the measured values ​​of the phase noise power spectrum index and the phase noise intensity coefficient as correction values, repeat steps (4)-(6) of the signal modulation module, and output the iterative optimization results;

[0035] 2) Extract the light spot collected by the camera and calculate the light spot uniformity. Correct the phase noise power spectrum index and the second proportional coefficient again. Repeat steps (4) to (6) of the signal modulation module until the error of the light spot uniformity is less than the tolerance or the number of iterations is sufficient.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. High simulation accuracy and rapid response: By setting up a two-stage optimization process, the phase noise power spectral index and the quadratic proportional coefficient are corrected respectively; and by using the output signal of the balanced photodetector and the camera spot as correction values ​​in sequence, closed-loop control is performed on the signal modulation module, which significantly reduces simulation error and provides a rapid response.

[0038] 2. Controllable control precision and strong adaptability to different scenarios: Through multi-level parameter correction and closed-loop algorithm, the laser coherence control precision can be flexibly controlled to adapt to different channel characteristics and application scenario requirements.

[0039] 3. Significant performance improvement: The proposed device and method can suppress the interference effect of the output spot of a multi-channel silicon-based optical phased array system, improve the uniformity of the spot, enhance the system's performance advantages in tracking and positioning, beam coupling and detection imaging, and greatly expand the system's effective operating distance and applicable scenarios.

[0040] 4. High practicality: The device structure can be realized by adding a signal modulation module to the prototype. It has a simple structure, is easy to implement, and has good prospects for engineering applications. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 is a structural block diagram of the system device of the present invention;

[0043] Figure 2 is a flowchart of the implementation method of the present invention;

[0044] Figure 3 shows the simulation results of the two-sided power spectral density of the white noise sequence according to the preferred embodiment of the present invention;

[0045] Figure 4 shows the simulation results and fitting curves of the power spectral density of the white noise sequence according to the preferred embodiment of the present invention.

[0046] Figure 5 shows the phase noise figure of the method proposed according to a preferred embodiment of the present invention. Simulation accuracy analysis;

[0047] Figure 6 shows the simulation accuracy analysis of the phase noise index φ of the method proposed according to a preferred embodiment of the present invention;

[0048] Figure 7 shows the simulation results of the laser coherence modulation method for a multi-channel silicon-based optical phased array system according to a preferred embodiment of the present invention.

[0049] The components are: 1. Laser, 2. First fiber beam splitter, 3. Electro-optic modulator, 4. Second fiber beam splitter, 5. First silicon-based optical phased array, 6. Second silicon-based optical phased array, 7. Camera, 8. Signal acquisition and processing module, 9. Signal modulation module, 10. Fiber optic coupler, and 11. Balanced photodetector. Detailed Implementation

[0050] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0051] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0052] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "proximal," "distal," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Physical quantities in formulas, unless otherwise specified, should be understood as basic quantities in the International System of Units (SI), or derived quantities derived from basic quantities through mathematical operations such as multiplication, division, differentiation, or integration.

[0053] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0054] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0055] This invention provides a laser coherence modulation device for multi-channel silicon-based optical phased array systems, such as... Figure 1 As shown, it includes a laser 1, a first fiber beam splitter 2, an electro-optic modulator 3, a second fiber beam splitter 4, a first silicon-based optical phased array 5, a second silicon-based optical phased array 6, a camera 7, a signal acquisition and processing module 8, a signal modulation module 9, a fiber coupler 10, and a balanced photodetector 11.

[0056] The input end of the first fiber beam splitter 2 is connected to the output end of the laser 1. The first fiber beam splitter 2 has three output ends: the first output end is connected to the input end of the fiber coupler 10, the second output end is connected to the input end of the second silicon-based optical phased array 6, and the third output end is connected to the input end of the electro-optic modulator 3.

[0057] The input end of the second fiber beam splitter 4 is connected to the output end of the electro-optic modulator 3. The second fiber beam splitter 4 has two output ends. The first output end outputs a laser signal through the first silicon-based optical phased array 5, which is combined with the laser signal output by the second silicon-based optical phased array 6 on the target surface of the camera 7. The second output end is connected to the input end of the fiber coupler 10, and the output end of the fiber coupler 10 is connected to the input end of the balanced photodetector 11.

[0058] The input terminal of the signal acquisition and processing module 8 is connected to the output terminal of the camera 7 and the output terminal of the balanced photodetector 11, and the output terminal of the signal acquisition and processing module 8 is connected to the input terminal of the signal modulation module 9. The output terminal of the signal modulation module 9 is connected to the input terminal of the electro-optic modulator 3.

[0059] In the basic implementation of this laser coherence modulation device, laser 1 generates a single-frequency continuous-wave laser signal, which is then split into three beams by a first fiber beam splitter 2. One beam is input to an electro-optic modulator 3 to modulate the required phase noise for the first silicon-based optical phased array 5 to modulate coherence; the second beam is input to a second silicon-based optical phased array 6, and its output beam serves as the reference light for the camera 7 to monitor interference effects; the third beam is input to a fiber coupler 10 as the local oscillator light for coherence detection. Generally, for example, in this embodiment, the three beams split by the first fiber beam splitter 2 have the same power.

[0060] One beam from the second fiber optic beam splitter 4 is input as signal light to the fiber optic coupler 10. After coherent mixing with the local oscillator, it is received by the balanced photodetector 11 to monitor the coherence modulation effect in real time. Generally, the second fiber optic beam splitter 4 also splits the light in an even manner to ensure that the output power of the two paths is consistent.

[0061] On the other hand, the present invention also provides a laser coherence modulation method for multi-channel silicon-based optical phased array systems, which is implemented by the modulation device described above, and the flowchart is as follows. Figure 2 As shown. The specific steps are as follows:

[0062] ① The signal modulation module 9 generates a laser phase noise sequence, which is then modulated by the electro-optic modulator 3;

[0063] ② The signal acquisition and processing module 8 extracts the phase of the monitoring signal output by the balanced photodetector 11 and corrects the parameters in the signal modulation module 9 based on the error amount;

[0064] ③ The signal acquisition and processing module 8 extracts the light spot acquired by the camera 7, and corrects the parameters in the signal modulation module 9 again based on the light spot uniformity error.

[0065] ④ When the uniformity of the light spot acquired by camera 7 meets the set value, the system completes the laser coherence control and outputs the closed-loop control result.

[0066] The signal modulation module 9 is configured to perform the following steps:

[0067] ① Generate white noise time-domain sequence ,in For sampling point number ( Performing a Discrete Fourier Transform (DFT) on it yields the frequency domain sequence. ,in The index of the frequency domain component ( );

[0068] ② For frequency domain sequences Perform spectral filtering: ,in The phase noise power spectral index, i.e. ,in For phase noise power spectral density, Frequency (unit: Hz) Indicates the phase noise intensity coefficient;

[0069] ③ Perform a discrete inverse Fourier transform on the filtered frequency domain signal to obtain the time domain sequence. ,in The sampling interval;

[0070] ④ Parameter initialization. Set the quadratic scaling factor. The initial value is 1, and the initial time-domain noise amplitude is calculated. , recorded as The initial phase noise sequence is obtained as follows: ; The present invention aims to iteratively obtain the target parameters, but in practice, these parameters cannot be directly controlled. It is necessary to To regulate, that is, through the secondary proportional coefficient Correction;

[0071] ⑤ Perform power spectral density analysis on the phase noise sequence to determine the phase noise power spectral index. and phase noise intensity coefficient The measured values ​​are respectively and ;

[0072] ⑥ If the measured value With target value The error is greater than the tolerance. To reduce this error, the phase noise power spectrum index is dynamically adjusted within a preset search interval; specifically, based on the measured values... Relative to target value The deviation direction is used to select a new correction value within the search space above and below the initial value. Then, the spectral filtering and subsequent processes in step ② are re-executed until the error converges to within the tolerance range or the number of iterations is sufficient. In this embodiment, the preset initial search interval is centered on the initial value and has a width of ±20% of the initial value;

[0073] ⑦ If the measured value With target value The error is greater than the tolerance. To reduce this error, the quadratic proportional coefficient is dynamically adjusted within a preset search interval. Specifically, based on the measured values... Relative to target value The deviation direction is used to select a new correction value within the search space above and below the initial value. (That is, alternating between trying different values ​​within the range greater than and less than the initial value), and then re-execute step ④ to calculate the time-domain noise amplitude and construct the phase noise sequence until the error converges to within the tolerance range or the number of iterations is sufficient. In this embodiment, the preset initial search interval is centered on the initial value and has a width of ±20% of the initial value;

[0074] ⑧ Output iterative optimization results (i.e., the final generated phase noise sequence), its expression is: ,in This represents the final time-domain noise amplitude after iterative correction.

[0075] The signal acquisition and processing module 8 is configured to perform the following steps:

[0076] ① Extract the phase of the output signal from the balanced photodetector 11 and calculate the phase noise power spectral index. and phase noise intensity coefficient The measured value is used as the correction value. Repeat steps 6-8 of the signal modulation module 9 and output the iterative optimization result.

[0077] ② Extract the light spot collected by camera 7 and calculate the light spot uniformity. Correct the phase noise power spectrum index and the second proportional coefficient again. Repeat the execution steps ⑥-⑧ of signal modulation module 9 until the error of light spot uniformity is less than the tolerance or the number of iterations is sufficient.

[0078] To make the description of the embodiments of the present invention clearer, the following description and explanation are given in conjunction with preferred embodiments.

[0079] The preferred embodiment of the present invention aims to control the coherence between the output beams of different channels of a silicon-based optical phased array, suppress non-uniform interference fringes, and improve the uniformity of the light spot.

[0080] White noise ( Taking (e.g.) as an example, we will demonstrate the simulation effect of the signal modulation module. Figure 3 for The power spectrum analysis results of the generated phase noise sequence under the given conditions show that the measured curve (black solid line) and the theoretical curve (red solid line) are in good agreement, both being Lorentz lines.

[0081] To verify the accuracy of the phase noise figure fitting, white noise figures were set separately. for , , , , This covers the linewidth range of common lasers from 1 kHz to 10 MHz. The logarithmic coordinates of the one-sided power spectrum of the generated noise sequence are taken, as shown below. Figure 4 As shown in the figure. The simulation curves for each group were fitted, and the fitted curves are shown as the solid red lines. The results also indicate whether the values ​​meet the set parameters. The theoretical curve (green dashed line). For each white noise figure... Under the given settings, the simulation curve, the fitted curve, and the theoretical curve match very well.

[0082] To further compare the degree of agreement between the fitted values ​​and the theoretical values, Seventeen sampling points were set proportionally between the points. At each sampling point, 500 sets of laser phase noise sequences were generated using a spectral filtering method. The one-sided power spectrum of each sequence was calculated and fitted. The mean and variance of the fitted white noise coefficient values ​​were plotted against the setpoint curve on a logarithmic coordinate system, as shown below. Figure 5 As shown. The blue curve represents the coefficient terms in 500 sets of phase noise sequences. The mean of the fitted values ​​is shown in the figure. The green shading represents the variance of the fitted values ​​from 500 sets of data, and the pink squares represent the setpoints (the top left is a magnified view). The relative error between the mean of the fitted values ​​and the setpoints is calculated, as shown by the purple curve in the figure. Under each setpoint, the average relative error between the two is within 0.12.

[0083] The exponential term of white noise In the statistical analysis of 500 sets of data, the index item was... The mean and variance of the fitted values, and the setpoint curve are plotted on... Figure 6 In the logarithmic coordinate system, the setpoints (pink squares) and fitted values ​​(blue straight lines) match very well. At each setpoint, the relative error between the two (purple curve) is within [a certain range]. Within.

[0084] The preferred embodiment of the present invention provides simulation results of a laser coherence modulation method for multi-channel silicon-based optical phased array systems.

[0085] Optionally, laser 1 can be a narrow linewidth laser with a working wavelength of 1550 nm. A lithium niobate (LiNbO3) electro-optic frequency shifter with a dual parallel Mach-Zehnder structure is used for single-sideband I / Q modulation (In-Phase and Quadrature Modulator).

[0086] Optionally, the system includes two silicon-based optical phased array channels with identical parameters, and the element spacing is [missing information]. The number of array elements is 16, and the fast axis scanning range is... The slow axis direction provides Gaussian beam expansion output (without scanning function). Optionally, the channel spacing between the two silicon-based optical phased arrays is... The beams are all pointing in the same direction .

[0087] Optionally, the coefficient of variation (CV) and peak-to-valley ratio (PV) can be used as quantitative indicators of spot uniformity to evaluate the degree of uniformity of interference fringe intensity. The coefficient of variation is the standard deviation of the intensity within the spot region. With average strength The ratio, i.e. The peak-to-valley intensity ratio is the ratio of the maximum to the minimum intensity within the light spot area. For both indicators, the smaller the value, the more uniform the stripes.

[0088] Figure 7 In the diagram (a), the output spot of a single silicon-based optical phased array (OPA) channel exhibits a Gaussian intensity distribution. When the pointing angles of the output spots of a dual-channel OPA are the same, the fixed phase difference between the two beams, due to their identical center wavelengths, produces alternating bright and dark interference fringes, such as... Figure 7 As shown in (b) in the figure, it is not conducive to imaging and beam positioning.

[0089] Therefore, this invention innovatively employs a laser coherence modulation device and method based on an electro-optic modulator, generating an intensity-controllable phase noise sequence through the aforementioned spectral filtering method to dynamically control the beam coherence. Figure 7 As shown in (c), by adjusting the mean square value of the phase noise sequence to 3.5 rad, the interference effect between light spots was effectively suppressed.

[0090] Figure 7 Figure (d) shows the comparison results of the center intensity of the light spot under the above three conditions. It can be seen that before modulation, although the center intensity of the dual-channel light spot is four times that of the single-spot light spot (consistent with the theoretical value), its intensity distribution exhibits significant fluctuations along the fast axis, with an intensity variation coefficient (CV) of 3.493 and a peak-to-valley intensity ratio (PV) of 9.481, indicating a significant interference effect. After modulation, the CV value is optimized to 2.783 (the theoretical reference value is 2.782), and the PV value is optimized to 4.998 (the theoretical reference value is 2.289). It is evident that, although the published coherence modulation method sacrifices nearly 50% of the light intensity, the light spot uniformity is improved by approximately 25.5%, approaching the theoretical optimal value. The light spot distribution is relatively uniform, the outline is regular, and it is easy to apply subsequently, verifying the effectiveness of the device and method published in this invention.

[0091] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0092] The above embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A laser coherence modulation device for a multi-channel silicon-based optical phased array system, characterized in that, The device includes: The first fiber beam splitter (2) has its input end connected to the output end of the laser (1). The first fiber beam splitter (2) has three output ends: the first output end is connected to the input end of the fiber coupler (10), the second output end is connected to the input end of the second silicon-based optical phased array (6), and the third output end is connected to the input end of the electro-optic modulator (3). The second fiber beam splitter (4) has its input end connected to the output end of the electro-optic modulator (3). The second fiber beam splitter (4) has two output ends. The first output end outputs a laser signal through the first silicon-based optical phased array (5), which is combined with the laser signal output by the second silicon-based optical phased array (6) on the target surface of the camera (7). The second output end is connected to the input end of the fiber coupler (10), and the output end of the fiber coupler (10) is connected to the input end of the balanced photodetector (11). The signal acquisition and processing module (8) extracts the phase of the monitoring signal output by the balanced photodetector (11) and the light spot acquired by the camera (7), and corrects the parameters in the signal modulation module (9); The signal modulation module (9) generates a laser phase noise sequence and modulates the laser signal through the electro-optic modulator (3).

2. The laser coherence modulation device for a multi-channel silicon-based optical phased array system according to claim 1, characterized in that, The output of the signal modulation module (9) is connected to the input of the electro-optic modulator (3); the input of the signal acquisition and processing module (8) is connected to the output of the camera (7) and the output of the balanced photodetector (11), and the output of the signal acquisition and processing module (8) is connected to the input of the signal modulation module (9).

3. The laser coherence modulation device for a multi-channel silicon-based optical phased array system according to claim 1, characterized in that, The performance parameters of the first silicon-based optical phased array (5) are the same as those of the second silicon-based optical phased array (6).

4. The laser coherence modulation device for a multi-channel silicon-based optical phased array system according to claim 1, characterized in that, The first fiber beam splitter (2) splits the light into three beams; one beam is input to the electro-optic modulator (3) to modulate the required phase noise for the first silicon-based optical phased array (5) to control coherence; the second beam is input to the second silicon-based optical phased array (6) and the output beam is used as the reference light for the camera (7) to monitor the interference effect; the third beam is input to the fiber coupler (10) as the local oscillator light for coherent detection.

5. The laser coherence modulation device for a multi-channel silicon-based optical phased array system according to claim 1, characterized in that, The second fiber beam splitter (4) inputs the signal light to the fiber coupler (10), and after coherent mixing with the local oscillator, it is received by the balanced photodetector (11) to monitor the coherence modulation effect in real time.

6. A method for controlling the laser coherence of a multi-channel silicon-based optical phased array system based on the control device described in any one of claims 1-5, characterized in that, The steps of this method are as follows: S1: The signal modulation module (9) generates a laser phase noise sequence and modulates the laser signal through the electro-optic modulator (3); S2: The signal acquisition and processing module (8) extracts the phase of the monitoring signal output by the balanced photodetector (11) and corrects the parameters in the signal modulation module (9) according to the error amount; S3: The signal acquisition and processing module (8) extracts the light spot acquired by the camera (7) and corrects the parameters in the signal modulation module (9) again based on the light spot uniformity error. S4: When the uniformity of the light spot collected by the camera (7) meets the set value, the laser coherence modulation is completed and the closed-loop control result of the output signal modulation module (9) is output.

7. The laser coherence modulation method according to claim 6, characterized in that, The signal modulation module (9) is configured to perform the following steps: (1) Generate a white noise time-domain sequence, and perform spectral filtering based on the phase noise power spectral index and phase noise intensity coefficient, and then convert it into a time-domain sequence; (2) Set the initial value of the quadratic proportional coefficient, calculate the initial time-domain noise amplitude, and calculate the initial phase noise sequence; (3) Perform power spectral density analysis on the initial phase noise sequence to determine the measured values ​​of the phase noise power spectral index and the phase noise intensity coefficient; (4) If the error between the measured value of the phase noise power spectrum index and the target value is greater than the tolerance, the phase noise power spectrum index is dynamically adjusted within the preset search interval with the aim of reducing the error, and the spectrum filtering process of step (1) is executed again until the error is less than the tolerance or the number of iterations is sufficient. (5) If the error between the measured value of the phase noise intensity coefficient and the target value is greater than the tolerance, then with the aim of reducing the error, the second proportional coefficient is dynamically adjusted within the preset search interval, and step (2) is executed again until the error is less than the tolerance or the number of iterations is sufficient. (6) Output the final phase noise sequence generated after iterative optimization.

8. The laser coherence modulation method according to claim 7, characterized in that, Step (1) is as follows: (1.1) Generate a white noise time-domain sequence, perform a discrete Fourier transform on it, and obtain a frequency-domain sequence; (1.2) The phase noise power spectral index is obtained based on the phase noise power spectral density and the phase noise intensity coefficient, and the frequency domain sequence is spectral filtered based on the phase noise power spectral index; (1.3) Perform discrete inverse Fourier transform on the frequency domain signal after spectral filtering to obtain the time domain sequence.

9. The laser coherence modulation method according to claim 8, characterized in that, The signal acquisition and processing module (8) is configured to perform the following steps: 1) Extract the phase of the output signal of the balanced photodetector (11), calculate the measured values ​​of the phase noise power spectrum index and the phase noise intensity coefficient as correction values, repeat steps (4)-(6) of the signal modulation module (9), and output the iterative optimization results; 2) Extract the light spot collected by the camera (7) and calculate the light spot uniformity. Correct the phase noise power spectrum index and the second proportional coefficient again. Repeat steps (4) to (6) of the signal modulation module (9) until the error of the light spot uniformity is less than the tolerance or the number of iterations is sufficient.

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