A method and system for optimizing diffraction efficiency of liquid crystal optical phased arrays

Abstract

This invention discloses a method and system for optimizing the diffraction efficiency of liquid crystal optical phased arrays (LCDs). Its purpose is to address the problem of low diffraction efficiency in existing LCDs under large-angle incident conditions. This invention adjusts the incident polarization of the LCD to find the optimal incident polarization for different incident angles, achieving diffraction efficiency comparable to that under normal incident conditions even at large-angle incident scenarios. This invention uses a linearly polarized laser beam expander system, a polarization modulation module, and a signal generator to control the polarization state of the light incident on the LCD. It monitors the emitted light energy using a photodetector and utilizes a computer for incident polarization control, emitted light power analysis, and optimization program implementation. This invention can automatically find the optimal incident polarization of the LCD, thereby significantly improving its diffraction efficiency under large-angle incident conditions.

Description

Technical Field

[0001] This invention belongs to the field of all-solid-state liquid crystal beam scanning, specifically relating to a method and system for optimizing the diffraction efficiency of liquid crystal optical phased arrays. Background Technology

[0002] Liquid crystal spatial light modulators (LCoS-SLMs) combine efficient liquid crystal modulation materials with mature complementary metal-oxide-semiconductor (CMOS) silicon backplane technology. They exhibit significant advantages in spatial resolution (exceeding native 4K), fill factor (greater than 90%), phase modulation levels (more than 256 levels), reliability, and operational flexibility. As a result, they are widely used in beam deflection fields such as optical tweezers, wavelength selective switches (WSS), and lidar detection and ranging (LiDAR).

[0003] Existing LCoS-SLMs are mostly used with a normal incident beam. To separate the incident and diffracted beams, a beam splitter (BS) is typically placed in front of the LCoS-SLM, but this introduces higher insertion loss and increases the complexity of the optical path system. In contrast, using an oblique incident beam simplifies the optical path, improves light utilization efficiency, and expands the beam control range. However, the diffraction efficiency of LCoS-SLMs decreases significantly with increasing incident angle. Therefore, most commercial LCoS-SLMs are typically recommended to operate at incident angles less than 10°. These characteristics greatly limit the application of LCoS-SLMs in high-efficiency and large-angle beam control systems.

[0004] Literature (C. Sun, B. Zhang, S. Zha, Z. Yuan and J. Lu, "High-EfficiencyBeam Steering LCOS for Wavelength Selective Switch," in IEEE Photonics Technology Letters (vol. 30, no. 19, pp. 1683-1686, 1 Oct. 1, 2018) designed a high birefringence... Large dielectric constant ( The liquid crystal mixture, at a relatively low operating voltage of 5.5V, achieved a wavelength greater than 4 at 1550 nm. With its high phase retardation, the LCoS-SLM designed based on this achieves a high diffraction efficiency of over 56.6% at a deflection angle of 4.5°.

[0005] The literature (S.-J. Son, TS Meetei, B. Park, et al., “Wide optical beamsteering lcos device for solid-state lidar applications,” IEEE PhotonicsTechnol. Lett. 36, 35–38 (2023).) designed a device with a pixel size of 3.6 Liquid crystal birefringence ( The LCoS-SLM, under a fixed large-angle oblique incidence of 45°, can achieve a maximum beam steering angle of ±15.6°. However, at the maximum beam steering angle, the first-order diffraction efficiency of the device is only 2.28%. Therefore, although the beam steering angle range of the LCoS-SLM can be further expanded under large-angle incidence, there is still a mutual constraint between its diffraction efficiency and the maximum beam steering angle.

[0006] Patent (CN116088244A) proposes a cascaded phased array optical scanning system, in which a liquid crystal optical phased array serves as the second-stage beam scanning device to perform secondary phase modulation on the scanning beam emitted from the first-stage silicon waveguide antenna at different angles. In this system, because the incident polarization of the liquid crystal optical phased array is affected by the outgoing polarization characteristics of the first-stage silicon waveguide antenna, the diffraction efficiency of the liquid crystal optical phased array may decrease significantly during large-angle scanning.

[0007] In summary, current liquid crystal optical phased array devices are all used in scenarios with relatively small incident angles, and cannot achieve a larger deflection angle field of view or higher diffraction efficiency. Furthermore, in applications with larger incident angles, the incident polarization is generally set to linear polarization parallel to the optical axis of the liquid crystal optical phased array device. This is a major reason why liquid crystal optical phased array devices have low diffraction efficiency at large incident angles. Summary of the Invention

[0008] To address the problems existing in the prior art, the present invention aims to provide a method and system for optimizing the diffraction efficiency of liquid crystal optical phased arrays. The present invention improves the diffraction efficiency of liquid crystal optical phased array devices in different incident angle scenarios by actively modulating the incident polarization of the liquid crystal optical phased array device to achieve polarization matching between the incident light and the liquid crystal optical phased array device.

[0009] The technical solution of this invention is as follows: On one hand, this invention provides a method for optimizing the diffraction efficiency of a liquid crystal optical phased array, the method comprising: For a specific incident angle, the polarization state of the incident light is adjusted to compensate for the attenuation of the projection component of the electric field vector in the e-ray direction of the liquid crystal molecule caused by the oblique incidence of the beam, thereby achieving polarization matching between the incident polarized light and the liquid crystal optical phased array device. By systematically changing the incident polarization and finding the optimal incident polarization corresponding to different incident angles, this polarization matching can maximize the phase modulation capability of the liquid crystal layer on the incident light, thereby enabling the diffraction efficiency of the liquid crystal optical phased array device to reach the optimal level at the specific incident angle.

[0010] Furthermore, to achieve the best optimization effect, when implementing the diffraction efficiency optimization method, the incident plane of the incident beam must be perpendicular to the main cross-section of the liquid crystal optical phased array device; wherein, the main cross-section is the plane containing the optical axis of the liquid crystal molecules and the surface normal of the liquid crystal optical phased array device.

[0011] Furthermore, the criterion for finding the optimal incident polarization of a liquid crystal optical phased array device at different incident angles is that the diffraction efficiency of the diffracted beam generated by loading a blazed grating phase diagram of arbitrary period onto the liquid crystal optical phased array reaches its maximum at the set incident angle.

[0012] Furthermore, the diffraction efficiency of a liquid crystal optical phased array device can be considered as the incident angle. and incident polarization azimuth angle Ellipticity function ,in At different incident angles You can find a set below. This improves the diffraction efficiency of liquid crystal optical phased array devices. Reach the maximum.

[0013] Furthermore, at different incident angles When the diffraction efficiency of a liquid crystal optical phased array device reaches its maximum, the optimal incident polarization satisfies the following relationship: a) Azimuth angle of optimal incident polarization With the angle of incidence The increase of is monotonically changing; b) Numerically, the azimuth angle It can be approximated as the angle of incidence. .

[0014] Furthermore, the principle of the diffraction efficiency optimization method of the present invention is to compensate for the attenuation of the projection component of the electric field vector on the e-light direction of the liquid crystal molecule caused by the oblique incidence of the light beam, thereby maximizing the phase modulation capability of the liquid crystal layer on the incident light, and thus enabling the diffraction efficiency of the liquid crystal optical phased array device to reach the optimal at the corresponding incident angle.

[0015] Existing diffraction efficiency improvement methods based on phase distribution optimization are generally based on compensating for crosstalk effects between liquid crystal pixels and in the fly-scan area, and correcting phase profile distortion caused by edge field effects in order to achieve accurate compensation for edge field effects.

[0016] Therefore, the two methods described above optimize the diffraction efficiency of liquid crystal optical phased arrays from two different dimensions: polarization control and phase distribution control. These two methods are not contradictory in principle. Thus, when the method provided by this invention is used in conjunction with other phase distribution optimization algorithms, their optimization effects can be superimposed and enhanced, thereby further improving the overall diffraction efficiency of the liquid crystal optical phased array.

[0017] On the other hand, the present invention also provides a diffraction efficiency optimization system for liquid crystal optical phased arrays, the system comprising: Linearly polarized laser beam expander systems are used to generate linearly polarized beams with a specific polarization direction. The polarization modulation module is used to actively polarize the incident light of the liquid crystal optical phased array. Liquid crystal optical phased arrays generate blazed phase gratings through electronic modulation, thereby producing constructive interference on the wavefront of incident light at a certain order, achieving directional deflection of the beam. Photodetector, used to quantitatively measure the intensity of diffracted beams from liquid crystal optical phased arrays; A signal generator is used to generate voltage signals to drive the polarization modulation module; The computer is used to process the data collected by the photodetector in real time and output corresponding drive commands to the signal generator based on the feedback signal.

[0018] Furthermore, the linearly polarized laser beam expander system comprises an infrared laser source that generates near-infrared light, a beam expander lens, an aperture, and polarizers and half-wave plates for adjusting the polarization of the light source's output. The fiber optic emitting end of the laser source is located at the front focal point of the beam expander lens, and the focal length of the beam expander lens must be matched with the divergence angle of the light source's output.

[0019] Furthermore, the output polarization of the linearly polarized laser beam expander system can be adjusted by changing the transmission direction of the polarizer and the fast axis direction of the half-wave plate, which can maximize the energy utilization of the laser source and ensure a high degree of linear polarization of the output light.

[0020] Furthermore, the polarization modulation module needs to be placed in front of the liquid crystal optical phased array; the polarization modulation module consists of two liquid crystal variable phase delayers LCVR1 and LCVR2, wherein the liquid crystal optical axis direction of LCVR1 is 45° and the liquid crystal optical axis direction of LCVR2 is 0°.

[0021] Furthermore, the phase modulation of the two liquid crystal variable phase delayers LCVR1 and LCVR2 is controlled by the drive signal of the signal generator.

[0022] Furthermore, the incident plane of the liquid crystal optical phased array must be perpendicular to the main cross-section (the plane containing the optical axis of the liquid crystal molecules and the surface normal of the liquid crystal optical phased array device).

[0023] Furthermore, the driving signal of the signal generator is an AC square wave voltage with adjustable amplitude and frequency.

[0024] Furthermore, the computer needs to process the diffraction intensity data of the liquid crystal optical phased array collected by the photodetector in real time, and independently adjust the loading voltage of the two liquid crystal variable phase delayers based on the feedback.

[0025] The beneficial effects of this invention are as follows: 1) This invention effectively compensates for phase modulation attenuation caused by oblique incidence of the beam simply by adjusting the polarization state of the incident light, thereby significantly improving the diffraction efficiency of the liquid crystal optical phased array in large-angle incidence scenarios. This method is simple to operate and effectively broadens the application potential of oblique incidence architectures in all-solid-state beam control systems.

[0026] 2) By optimizing polarization matching, this invention can further expand the angle control range of liquid crystal optical phased arrays, reduce their sensitivity and limitations to the angle of incident beams, and enhance the adaptability and stability of the device in complex optical paths.

[0027] 3) The optimized system described in this invention has a simple optical path structure. The optimal incident polarization found for a specific incident angle can be applied to beam control at all exit angles under the incident condition, thereby improving the versatility and operational efficiency of the system. Attached Figure Description

[0028] 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.

[0029] Figure 1 The diagram shown is a flowchart illustrating the principle of a diffraction efficiency optimization method for liquid crystal optical phased arrays according to the present invention.

[0030] Figure 2 The diagram shows a light propagation schematic for beam scanning using a reflective liquid crystal optical phased array under both normal and large-angle incident conditions.

[0031] Figure 3The diagram shown is a block diagram of a diffraction efficiency optimization system for liquid crystal optical phased arrays according to the present invention.

[0032] Figure 4 The diagram shows a schematic of the optical path structure of a diffraction efficiency optimization system for a liquid crystal optical phased array according to the present invention.

[0033] Figure 5 The diagram shown is a schematic representation of the structure of the dual-layer liquid crystal phase-variable delayer in the polarization modulation module of the present invention.

[0034] Figure 6 The figure shows the diffraction efficiency curve of a reflective liquid crystal spatial light modulator (LCoS) under 51.5° incident light as a function of angle. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, preferred embodiments of the invention are given below with reference to the accompanying drawings to illustrate the technical solutions in detail. It should be understood that the specific implementation examples described herein are merely illustrative and not intended to limit the scope of the invention.

[0036] like Figure 1 As shown, this invention discloses a method for optimizing the diffraction efficiency of liquid crystal optical phased arrays, the specific steps of which are as follows: 1) A beam of linearly polarized light is used as the incident light and is irradiated onto the liquid crystal optical phased array at a specific incident angle; 2) The electric field vector of the incident light can be decomposed into an e-ray component parallel to the optical axis of the liquid crystal and an o-ray component perpendicular to the optical axis of the liquid crystal. Among them, the e-ray is phase-modulated by the blazed grating, diffracts and is deflected to the +1 order, and becomes the outgoing diffracted light; while the o-ray is not phase-modulated, propagates along the original direction, and remains as the zero-order light energy.

[0037] 3) Monitor the energy of diffracted light using a photodetector device; 4) When the incident polarization state is adjusted, the ratio of the e-light component and the o-light component will change accordingly, which will affect the power of the outgoing diffracted light. 5) When the power of the outgoing diffracted light reaches its maximum, it can be considered that the e-light component corresponding to the incident polarization state has the highest proportion. The incident light and the liquid crystal optical phased array achieve polarization matching, the phase modulation capability of the liquid crystal layer on the incident light reaches its maximum, and the diffraction efficiency at this incident angle reaches its optimal level. 6) Output the optimal incident polarization of the liquid crystal optical phased array at this incident angle.

[0038] like Figure 2The diagram illustrates light propagation for beam scanning using a reflective liquid crystal optical phased array under both normal and large-angle incident conditions. The incident plane is perpendicular to the main cross-section of the liquid crystal optical phased array. The incident plane is defined as the plane formed by the wave normal of the incident light and the surface normal of the liquid crystal optical phased array. The main cross-section is the plane formed by the optical axis of the liquid crystal and the surface normal of the liquid crystal optical phased array. The transverse plane is perpendicular to the light propagation direction. Large-angle incident refers to an oblique incident situation with a large incident angle sufficient to significantly reduce the phase modulation capability of the liquid crystal layer, typically corresponding to the angle range within which the polarization state of the incident light needs to be compensated and adjusted according to the method described in claim 1.

[0039] When light is incident perpendicularly on a liquid crystal optical phased array, as the liquid crystal molecules rotate within the main cross section, their e-ray and o-ray directions remain unchanged and always parallel to the direction of the liquid crystal optical axis. Therefore, under normal incidence, the diffraction efficiency is highest when the polarization direction of the incident light is kept parallel to the direction of the liquid crystal optical axis. When light is incident on the liquid crystal optical phased array at a large angle, as the liquid crystal molecules rotate within the main cross section, their e-ray and o-ray directions change with the incident angle and the direction of the liquid crystal molecule's director. Therefore, under large-angle incidence, the diffraction efficiency is no longer highest when the polarization direction of the incident light is kept parallel to the direction of the liquid crystal optical axis. It is necessary to adjust the polarization of the incident light to achieve polarization matching, thereby maximizing the phase modulation capability of the liquid crystal layer on the incident light so that the diffraction efficiency reaches the highest level again.

[0040] like Figure 3 As shown, the present invention provides a diffraction efficiency optimization system for liquid crystal optical phased arrays. The system includes a linearly polarized laser beam expander 1, a polarization modulation module 2, a liquid crystal optical phased array 3, a photodetector 4, a signal generator 5, and a computer 6.

[0041] The linearly polarized laser beam expander 1 is used to generate a linearly polarized infrared rectangular spot with a specific polarization direction and output it to the polarization modulation module 2 in a normal incidence manner.

[0042] The computer 6 is connected to the signal generator 5 and is used to send drive commands to the signal generator 5; The signal generator 5 is connected to the polarization modulation module 2 and is used to output a corresponding voltage driving signal to the polarization modulation module 2 according to the driving command.

[0043] The computer 6 is also connected to the liquid crystal optical phased array 3 to generate a blazed grating phase diagram with a specified period and convert it into a corresponding voltage control signal sequence, which is then input to the liquid crystal optical phased array 3.

[0044] The polarization modulation module 2 is disposed on the output optical path of the linearly polarized laser beam expander system 1 and is used to actively polarize the incident linearly polarized light according to the voltage driving signal; the modulated light is output to the liquid crystal optical phased array 3.

[0045] The liquid crystal optical phased array 3 spatially modulates the wavefront of the incident light based on the loaded blazed grating phase map, causing the light to diffract to a specific order.

[0046] The photodetector 4 is placed in the optical path of the specific diffraction order to receive diffracted light energy and perform photoelectric conversion, and then feeds back the converted electrical signal to the computer 6.

[0047] Computer 6 adjusts the drive command sent to signal generator 5 in real time based on the light intensity data fed back by photodetector 4. Signal generator 5 outputs an updated voltage drive signal to polarization modulation module 2 based on the drive command to adjust the polarization state of the light incident on liquid crystal optical phased array 3, thereby dynamically optimizing the diffraction efficiency of liquid crystal optical phased array 3.

[0048] The system of the present invention continues to operate through the above closed-loop control process until the diffracted light energy detected by the photodetector 4 reaches its maximum value. At this time, the system determines that the diffraction efficiency optimization target has been achieved and terminates the closed-loop control process.

[0049] One embodiment of the present invention for a diffraction efficiency optimization system for liquid crystal optical phased arrays is as follows: Figure 4As shown, the system comprises a linearly polarized laser beam expander 1, an LCVR component 21, a square aperture 22, a reflective liquid crystal spatial light modulator 31, an angle rotation stage 32, a Fourier lens 33, an optical power meter 41, an aperture 42, and a horizontal displacement stage 43. The linearly polarized laser beam expander 1 consists of a 1550nm light source 11, an optical fiber flange 12, a 200mm lens 13, a half-wave plate 14, and a polarizer 15. The 200mm lens 13 collimates the light spot emitted from the 1550nm light source 11 from the optical fiber flange 12, the half-wave plate 14 changes the linear polarization direction of the emitted light, and the polarizer 15 increases the degree of linear polarization of the emitted light. The LCVR component 21 polarizes the output light from the linearly polarized laser beam expander 1. The light spot is then adjusted by a square aperture 22 to the same size as the aperture of the reflective liquid crystal spatial light modulator 31, and incident on the modulator at a specific angle. This incident angle can be adjusted by the angle rotation stage 32 below the modulator. After being spatially modulated by the blazed grating in the reflective liquid crystal spatial light modulator 31, the incident light is deflected at a certain angle and incident on the Fourier lens 33. The front focal point of the Fourier lens 33 must coincide with that of the reflective liquid crystal spatial light modulator 31. Light emitted from the modulator at different angles from the modulator becomes a parallel beam after passing through the lens. The aperture 42 is positioned at the rear focal point of the Fourier lens 33, minimizing the light spot size on the plane containing the aperture 42. The horizontal displacement stage 43 controls the position of the optical power meter 41, ensuring accurate and complete collection of the diffracted beam's energy. The optical power meter 41 is connected to a computer, transmitting the intensity data of the diffracted beam to the computer for processing. Based on the intensity data fed back by the optical power meter 41, the computer updates the drive commands sent to the signal generator in real time. The signal generator outputs an adjusted voltage drive signal to the polarization modulation module, realizing dynamic adjustment of the diffraction efficiency of the reflective liquid crystal spatial light modulator 41. This closed-loop adjustment process is repeated. When the diffracted light intensity detected by the optical power meter 41 no longer increases, the system determines that the diffraction efficiency optimization is complete and automatically stops the adjustment.

[0050] One embodiment of the polarization modulation module 2 of the present invention for a diffraction efficiency optimization system of a liquid crystal optical phased array is as follows: Figure 5 As shown, it consists of two liquid crystal variable phase retarders, LCVR1 and LCVR2. The optical axis of LCVR1 is at 45°, and the optical axis of LCVR2 is at 0°. The phase modulation of both LCVR1 and LCVR2 is controlled by the drive signal from the signal generator.

[0051] If the output polarization of the linearly polarized laser beam expander system 1 is set to the horizontal direction (0°), the phase delay of LCVR2 can be adjusted by actively controlling the loading voltage of LCVR2. Set as At this point, the applied voltage of LCVR1 is actively adjusted using a signal generator, so that the phase delay of LCVR1 is... By continuously changing the azimuth angle, the incident polarization of the liquid crystal optical phased array 3 can always be linearly polarized. Phase delay with LCVR1 The following relationship must be satisfied: At this time From 0 to 2 azimuth It can cover all linear polarization directions by varying from 0° to 180°.

[0052] When the azimuth angle of the incident polarization of the liquid crystal optical phased array 3 Once set up, the applied voltages of LCVR1 and LCVR2 can be adjusted simultaneously to control the phase delay of LCVR1 and LCVR2. and The following relationship must be satisfied: At this time, the ellipticity of the incident polarization of the liquid crystal optical phased array 3 It allows for individual adjustment without affecting the azimuth angle of the incident polarization. Ellipticity of incident polarization Phase delay of LCVR1 and LCVR2 and The following relationship must be satisfied: like Figure 6 As shown, the diffraction efficiency of a reflective liquid crystal optical phased array (LCoS) was tested at different beam scanning angles under an incident angle of 51.5°. The tests were conducted for three scenarios: unoptimized state, state using only the phase distribution optimization method, and state using phase distribution optimization combined with the polarization modulation optimization method of this invention. The scanning angle range was... to .

[0053] Experimental results show that, compared with using only the phase distribution optimization method, combining phase distribution optimization with the polarization modulation optimization of this invention significantly improves the diffraction efficiency of LCoS. Taking an 8° deflection angle as an example, its diffraction efficiency can be increased to approximately 45% to 50%.

[0054] The LCoS device used in this experiment has a pixel pitch of 3.74. The operating band is 1550. .

[0055] Matters not covered in this invention are common knowledge.

[0056] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for optimizing the diffraction efficiency of a liquid crystal optical phased array, characterized in that, The method includes the following steps: The polarization state of the incident light is adjusted to compensate for the attenuation of the projection component of the electric field vector in the e-ray direction of the liquid crystal molecules caused by the oblique incident angle of the beam, thereby achieving polarization matching between the incident polarized light and the liquid crystal optical phased array. At this incident angle, the phase modulation capability of the liquid crystal layer on the incident light can be maximized through the above polarization matching, thereby making the diffraction efficiency of the liquid crystal optical phased array optimal at this incident angle.

2. The method for optimizing diffraction efficiency of liquid crystal optical phased arrays according to claim 1, characterized in that, The optimization method is compatible with other liquid crystal optical phased array phase distribution optimization algorithms, and when used in conjunction with other optimization algorithms, it can produce a superimposed and enhanced diffraction efficiency optimization effect.

3. The method for optimizing diffraction efficiency of liquid crystal optical phased arrays according to claim 1, characterized in that, The method for adjusting the polarization state of the incident light is to introduce a polarization modulation module in front of the liquid crystal optical phased array, and adjust the incident polarization of the liquid crystal optical phased array by changing the driving signal of the polarization modulation module.

4. The method for optimizing diffraction efficiency of liquid crystal optical phased arrays according to claim 3, characterized in that, The polarization modulation module includes any of the following implementation methods: a) An optical polarization device assembly consisting of a polarizer, a half-wave plate, and a quarter-wave plate; b) Active polarization modulation devices are used to achieve dynamically programmable polarization control.

5. The method for optimizing diffraction efficiency for liquid crystal optical phased arrays according to claim 1, characterized in that, To achieve polarization matching by adjusting the polarization state of the incident light, a photoelectric detection device needs to be introduced. The photoelectric detection device collects the light intensity data of the diffracted beam generated by the liquid crystal optical phased array with a phase diagram of an arbitrary period of blazed grating loaded at a set incident angle. The incident polarization corresponding to the highest diffraction efficiency of the liquid crystal optical phased array is the optimal incident polarization.

6. The method for optimizing diffraction efficiency for liquid crystal optical phased arrays according to claim 1, characterized in that, The polarization matching relationship between the incident light and the liquid crystal optical phased array varies with the incident angle, and different incident angles correspond to different optimal polarization states.

7. A diffraction efficiency optimization system for liquid crystal optical phased arrays for implementing the optimization method as described in any one of claims 1-6, characterized in that, The system includes: Linearly polarized laser beam expander systems are used to generate linearly polarized beams with a specific polarization direction. The polarization modulation module is used to actively polarize the incident light of the liquid crystal optical phased array. Liquid crystal optical phased arrays generate blazed phase gratings through electronic modulation, thereby producing constructive interference on the wavefront of incident light at a certain order, achieving directional deflection of the beam. Photodetector, used to quantitatively measure the intensity of diffracted beams from liquid crystal optical phased arrays; A signal generator is used to generate voltage signals to drive the polarization modulation module; The computer is used to process the data collected by the photodetector in real time and output corresponding drive commands to the signal generator based on the feedback signal.

8. The diffraction efficiency optimization system for liquid crystal optical phased arrays according to claim 7, characterized in that, The linearly polarized laser beam expander system consists of an infrared laser source that generates near-infrared light, a beam expander lens, an aperture, and a polarizer and a half-wave plate for adjusting the polarization of the light source output.

9. The diffraction efficiency optimization system for liquid crystal optical phased arrays according to claim 7, characterized in that, The polarization modulation module consists of two liquid crystal variable phase delayers, LCVR1 and LCVR2, wherein the liquid crystal optical axis of LCVR1 is 45° and the liquid crystal optical axis of LCVR2 is 0°; the phase modulation amount of the two liquid crystal variable phase delayers, LCVR1 and LCVR2, is controlled by the driving signal of the signal generator.

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