One-to-many space laser communication transmitting system and method based on liquid crystal phase regulation and control device

Abstract

The invention relates to a laser communication transmitting system and a control method thereof, in particular to a one-to-many space laser communication transmitting system and method based on a liquid crystal phase regulation and control device. In order to overcome the defect that in the prior art, different data is difficult to send to different users through a one-to-many emission method of a liquid crystal phase regulation and control device in a partitioned mode. The one-to-many space laser communication transmitting system based on the liquid crystal phase regulation and control device comprises a laser, a polarization modulator unit, a polarization beam combiner, a communication transmitting unit, a fine tracking galvanometer, a polarization phase regulation and control unit, a 1 / 4 wave plate unit and a liquid crystal polarization grating unit. The polarization modulator unit loads different communication data to s-polarized light and p-polarized light output by the laser respectively, and then different communication data are sent to multiple different directions by using the phase modulation characteristics of the polarization phase regulation and control unit and the liquid crystal polarization grating unit. Meanwhile, the invention further provides a communication transmitting method based on the system.

Description

Technical Field

[0001] The present invention relates to a laser communication transmitting system and a control method thereof, and in particular to a one-to-many space laser communication transmitting system and method based on a liquid crystal phase control device. Background Art

[0002] Space laser communication offers advantages such as wide bandwidth, large information capacity, excellent confidentiality, strong anti-interference capabilities, no spectrum restrictions, compact size, light weight, and low power consumption. It can meet the growing data demands of exploration missions and space-based communication networks. In recent years, the United States, Europe, and China have repeatedly demonstrated and verified inter-satellite and inter-satellite-to-ground space laser communication technology in orbit. Space laser communication technology has been widely used in low-Earth orbit satellite constellations.

[0003] In space laser communication systems, the aiming, capture, and tracking subsystems are crucial components. Through coarse and fine tracking, they enable rapid capture of spatial light, ensuring the beam's stable and efficient delivery to the communication receiver in real time, enabling high-speed data transmission. Existing space laser communication systems often use a rotating mechanical turntable, which achieves coarse tracking and capture of the light beam through mechanical rotation. However, the optical antennas on these turntables are bulky, heavy, and power-hungry, accounting for over 70% of the space laser terminal's total volume, weight, and power consumption. Furthermore, they suffer from high inertia and difficulty scalable for simultaneous multi-user communication, limiting the development of space laser communication terminals towards miniaturization, lightweighting, and flexible networking.

[0004] Liquid crystal phase control devices use phase modulation to perform beamforming, enabling non-mechanical beam deflection. They are compact, lightweight, and low-power. They can also achieve one-to-many beam transmission through zoned control, promising a potential replacement for mechanical turntables in space laser communications. However, the current one-to-many transmission method using liquid crystal phase control devices based on zoned control can only achieve one-to-many transmission of the same data, making it difficult to meet the need to send different data to different users. Summary of the Invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art that the one-to-many transmission method of the liquid crystal phase control device with divided regions is difficult to send different data to different users, and to provide a one-to-many spatial laser communication transmission system and method based on the liquid crystal phase control device.

[0006] To achieve the above objectives, the present invention provides the following technical solutions:

[0007] A one-to-many space laser communication transmission system based on a liquid crystal phase control device is special in that it includes a laser, a polarization modulator unit, a polarization beam combiner and a communication transmission unit connected in sequence to the laser output end, and a precision tracking galvanometer, a polarization phase control unit, a 1 / 4 wave plate unit and a liquid crystal polarization grating unit arranged in sequence along the transmission light path of the communication transmission unit; the laser is used to generate carrier linear polarization light and divide it into s-polarized light and p-polarized light output; the polarization modulator unit is used to load different communication data onto the s-polarized light and p-polarized light respectively; the polarization beam combiner is used to The invention is used to combine s-polarized light and p-polarized light into an optical signal output; the communication transmitting unit is used to receive and transmit the combined optical signal; the precision tracking galvanometer is used to adjust the angle of the combined optical signal and reflect it to the polarization phase control unit; the polarization phase control unit is used to change the modulation phase distribution to achieve continuous angular deflection of the optical signal; the 1 / 4 wave plate unit is used to convert s-polarized light and p-polarized light into left-handed circularly polarized light and right-handed circularly polarized light respectively; the liquid crystal polarization grating unit is used to perform discrete angular deflection on the left-handed circularly polarized light and the right-handed circularly polarized light, and transmit them to the corresponding receiving users.

[0008] Furthermore, the polarization phase control unit includes X polarization phase control components located in the same plane perpendicular to the optical signal transmission direction, where X≥1;

[0009] The quarter wave plate unit includes X quarter wave plates arranged in one-to-one correspondence with the X polarization phase control components;

[0010] The liquid crystal polarization grating unit includes X liquid crystal polarization grating modules arranged in a one-to-one correspondence with the X polarization phase control components.

[0011] Furthermore, the polarization phase control component includes a first liquid crystal optical phased array and a second liquid crystal optical phased array whose polarization directions are perpendicular to each other and are coaxially arranged;

[0012] The first liquid crystal optical phased array is used to modulate s-polarized light to deflect it;

[0013] The second liquid crystal optical phased array is used to modulate p-polarized light to deflect it.

[0014] Furthermore, the liquid crystal polarization grating module includes a first liquid crystal polarization grating component and a second liquid crystal polarization grating component, whose polarization directions are perpendicular to each other and coaxially stacked, and are used to diffract left-handed circularly polarized light and right-handed circularly polarized light respectively;

[0015] The first liquid crystal polarization grating component and the second liquid crystal polarization grating component each include multiple layers of liquid crystal polarization gratings coaxially stacked.

[0016] Furthermore, a transmitting mirror group is further provided at the output end of the communication transmitting unit for collimating the optical signal transmitted by the communication transmitting unit;

[0017] The polarization modulator unit is connected to the laser and the polarization beam combiner respectively through optical fibers;

[0018] The polarization beam combiner is connected to the communication transmitting unit via an optical fiber. The communication transmitting unit transmits the optical signal through free space to the transmitting mirror group, which collimates the optical signal and then transmits it to the precision tracking galvanometer.

[0019] An aperture expansion unit for expanding the optical signal is also provided between the fine tracking galvanometer and the polarization phase control unit.

[0020] Furthermore, the polarization modulator unit includes a first modulator and a second modulator for loading different communication data onto the s-polarized light and the p-polarized light, respectively;

[0021] The beam expansion unit is configured as a Maksutov catadioptric system.

[0022] Furthermore, the polarization phase control component includes two liquid crystal on silicon phased arrays with polarization directions perpendicular to each other and coaxially arranged, or the polarization phase control component includes two MEMS phased arrays with polarization directions perpendicular to each other and coaxially arranged.

[0023] At the same time, the present invention also provides a one-to-many space laser communication transmission method based on a liquid crystal phase control device. The one-to-many space laser communication transmission system based on the liquid crystal phase control device is special in that it includes the following steps:

[0024] S1. Analyze the initial deflection angle of the corresponding receiving user based on the initial position information of the receiving user and the initial position information of the one-to-many space laser communication transmission system, and decompose the initial deflection angle into the deflection angle of the corresponding polarization phase control unit and the deflection angle of the corresponding liquid crystal polarization grating unit;

[0025] S2. The laser emits laser light and splits it into s-polarized light and p-polarized light. The polarization modulator loads different communication data onto the s-polarized light and p-polarized light, respectively. The polarization beam combiner then combines the light into one optical signal, which is then transmitted by the communication transmitter.

[0026] S3. Precision tracking galvanometer deflects the light signal;

[0027] S4. The deflection angle of the polarization phase control unit corresponding to step S1 is converted into voltage control information, loaded into the polarization phase control unit, and controls the s-polarized light and p-polarized light in one optical signal to deflect to corresponding angles respectively;

[0028] The S5.1 / 4 wave plate unit converts s-polarized light and p-polarized light into left-handed circularly polarized light and right-handed circularly polarized light;

[0029] S6. The liquid crystal polarization grating unit deflects the left-handed circularly polarized light and the right-handed circularly polarized light in opposite directions at discrete angles and transmits them to the corresponding receiving users, completing one-to-many transmission of different communication data.

[0030] Furthermore, in step S1, the number of receiving users is 2X, where X≥1, and the initial deflection angles of the corresponding receiving users are recorded as θ1, θ2…, θ 2X The polarization phase control unit includes X polarization phase control components located in the same plane, and the polarization phase control components include a first liquid crystal optical phased array and a second liquid crystal optical phased array whose polarization directions are perpendicular to each other and are coaxially arranged; the initial deflection angle is decomposed according to the following formula:

[0031] θ1=θ 1″ +θ 1'

[0032] θ2=θ 2″ -θ 1' ...

[0034] θ 2X-1 =θ (2X-1)″ +θ X'

[0035] θ 2X =θ 2X″ -θ X'

[0036] Among them, θ 1″ ,...,θ (2X-1)″ is the deflection angle of the first liquid crystal optical phased array corresponding to the 1st, ..., 2X-1th receiving users, θ 2″ ,...,θ 2X″ is the deflection angle of the second liquid crystal optical phased array corresponding to the 2nd, ..., 2Xth receiving users, θ 1' ,...,θ x' is the deflection angle of the liquid crystal polarization grating unit.

[0037] Furthermore, step S4 is specifically as follows: converting the deflection angle of the polarization phase control unit corresponding to step S1 into voltage control information, and loading it onto the first liquid crystal optical phased array and the second liquid crystal optical phased array of the X regions in the polarization phase control unit, respectively. The first liquid crystal optical phased array of the X regions controls the s-polarized light to deflect θ 1″ ,...,θ (2X-1)″ , the second liquid crystal optical phased array controls the p-polarized light to deflect θ 2″,...,θ 2X″ .

[0038] Beneficial effects of the present invention:

[0039] 1. The present invention is based on a one-to-many space laser communication transmission system of a liquid crystal phase control device. By cooperating with a laser and a polarization modulator unit, different communication data are loaded simultaneously. Then, the phase modulation characteristics of the polarization phase control unit and the liquid crystal polarization grating unit are utilized to break through the limitation of traditional mechanical turntable optical antennas that cannot achieve one-to-many communication. Different communication data can be sent in multiple different directions respectively, thereby improving the flexibility and adaptability of the laser communication system and adapting to the application requirements of flexible networking of space laser communications.

[0040] 2. The one-to-many space laser communication transmission system based on the liquid crystal phase control device of the present invention realizes one-to-many transmission through a regional and polarization-divided manner. Compared with a single regional division method, the utilization rate of the light aperture is greatly improved, and it can adapt to the application requirements of large-aperture space laser communications.

[0041] 3. The present invention is based on a one-to-many spatial laser communication transmission system of a liquid crystal phase control device, in which the polarization phase control unit and the liquid crystal polarization grating unit are set up and used in corresponding areas, solving the adaptation problem of the liquid crystal optical phased array and the liquid crystal polarization grating during one-to-many transmission, and realizing one-to-many arbitrary-angle light beam deflection within a large angle range.

[0042] 4. The one-to-many spatial laser communication transmission method based on the liquid crystal phase control device of the present invention deflects s-polarized light and p-polarized light respectively through the polarization phase control unit and the liquid crystal polarization grating unit to achieve one-to-many transmission of different communication data. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural diagram of the second embodiment of the one-to-many space laser communication transmission system based on the liquid crystal phase control device of the present invention.

[0044] Description of reference numerals:

[0045] 1-Laser, 2-First modulator, 3-Second modulator, 4-Polarization beam combiner, 5-Communication transmitting unit, 6-Transmitting mirror group, 7-Precision tracking galvanometer, 8-Beam expansion unit, 9-First liquid crystal optical phased array, 10-Second liquid crystal optical phased array, 11-1 / 4 wave plate unit, 12-Liquid crystal polarization grating unit. DETAILED DESCRIPTION

[0046] Example 1

[0047] The one-to-many spatial laser communication transmission system based on the liquid crystal phase control device of the present invention is used to realize one-to-many transmission of laser communication of different communication data, and has the characteristics of large aperture and flexible communication.

[0048] The one-to-many spatial laser communication transmission system of this embodiment includes a laser 1, a polarization modulator unit, a polarization beam combiner 4, and a communication transmission unit 5, which are connected in sequence. Furthermore, a transmitting mirror group 6, a precision tracking galvanometer 7, a beam expander 8, a first liquid crystal optical phased array 9, a second liquid crystal optical phased array 10, a quarter-wave plate unit 11, and a liquid crystal polarization grating unit 12 are sequentially arranged along the transmission optical path of the communication transmission unit 5. The polarization modulator unit includes a first modulator 2 and a second modulator 3. The first modulator 2 is configured as an s-polarization modulator, and the second modulator 3 is configured as a p-polarization modulator.

[0049] The two output ends of the laser 1 are connected to the input ends of the first modulator 2 and the second modulator 3 through optical fibers, respectively, for generating carrier linearly polarized light, and dividing it into s-polarized light (vertically polarized light) and p-polarized light (parallel polarized light) and outputting them to the first modulator 2 and the second modulator 3 respectively.

[0050] The first modulator 2 and the second modulator 3 are used to modulate the communication data of different receiving users. In this embodiment, the first modulator 2 modulates the communication data of one receiving user and loads it onto s-polarized light, and the second modulator 3 modulates the communication data of another receiving user and loads it onto p-polarized light.

[0051] The input end of the polarization beam combiner 4 is connected to the output ends of the first modulator 2 and the second modulator 3 respectively through optical fibers. The output end of the polarization beam combiner 4 is further connected to the input end of the communication transmission unit 5 through optical fibers. The polarization beam combiner 4 combines the s-polarized light and the p-polarized light into a single beam and transmits it to the communication transmission unit 5. The communication transmission unit 5 transmits the optical signal through free space to the transmitting mirror group 6.

[0052] Transmitting mirror assembly 6 is used to collimate the optical signal emitted by communication transmitting unit 5. Fine tracking galvanometer 7 receives and reflects the collimated optical signal, controlling its angle via voltage to achieve high-precision, small-angle pointing of the optical signal. In this embodiment, the central axes of the incident and reflected light from fine tracking galvanometer 7 are perpendicular to each other.

[0053] Beam expander 8 is configured as a Maksutov catadioptric system, where the lenses and reflectors are all spherical, and the eyepiece consists of three elements, used to amplify the aperture of the incident light beam. Beam expander 8 has an expansion ratio of N. The apertures of the first liquid crystal optical phased array 9, the second liquid crystal optical phased array 10, the quarter-wave plate unit 11, and the liquid crystal polarization grating unit 12 are N times greater than those of the optical components preceding beam expander 8. Other beam expansion systems may also be used in other embodiments of the present invention.

[0054] The first liquid crystal optical phased array 9 utilizes an s-polarized liquid crystal optical phased array, while the second liquid crystal optical phased array 10 utilizes a p-polarized liquid crystal optical phased array. The two are coaxially arranged to form a polarization phase control component. The operating principle of the liquid crystal optical phased array is as follows: when an external voltage is applied to the liquid crystal optical phased array, linearly polarized light parallel to the optical axis of the liquid crystal optical phased array will experience an angular deflection relative to its original propagation direction, while linearly polarized light perpendicular to the optical axis will maintain its original propagation direction. Applying different voltage values will cause the transmitted laser beam to deflect at different angles. Therefore, by using two liquid crystal optical phased arrays with polarization directions perpendicular to each other, s-polarized light and p-polarized light can be deflected and modulated to different directions, achieving a small range of continuous angle deflection.

[0055] In this embodiment, the optical axis direction of the first liquid crystal optical phased array 9 is the s-polarization direction, and the s-polarized light is modulated and deflected, while the p-polarized light has no modulation effect and is still transmitted in the original direction. The optical axis direction of the second liquid crystal optical phased array 10 is the p-polarization direction, and the p-polarized light is modulated and deflected, while the s-polarized light has no modulation effect and is still transmitted in the original direction.

[0056] In other embodiments of the present invention, the positions and optical axis polarization directions of the first liquid crystal optical phased array 9 and the second liquid crystal optical phased array 10 can be interchanged. The first liquid crystal optical phased array 9 and the second liquid crystal optical phased array 10 can also be replaced with other polarization-dependent phase control devices, such as liquid crystal on silicon phased arrays, MEMS phased arrays, etc.

[0057] The quarter wave plate unit 11 is used to convert s-polarized light and p-polarized light into left-handed circularly polarized light and right-handed circularly polarized light required by the liquid crystal polarization grating unit 12. In this embodiment, the quarter wave plate unit 11 includes a quarter wave plate.

[0058] The liquid crystal polarization grating unit 12 is used for deflection over a wide range of discrete angles. It switches between normal operation and inactivity under the influence of a control voltage, and the diffraction order switches between zero and plus or minus one. When discrete angle deflection is not required, the diffraction order is zero. The liquid crystal polarization grating unit 12 includes a liquid crystal polarization grating module. To achieve deflection along two axes, the liquid crystal polarization grating module includes a first liquid crystal polarization grating component and a second liquid crystal polarization grating component coaxially stacked with mutually perpendicular polarization directions. These components, when stacked, deflect polarized light in two directions. The first and second liquid crystal polarization grating components each include coaxially stacked layers of liquid crystal polarization gratings to increase the deflection angle range.

[0059] The operating principle of a liquid crystal polarization grating is as follows: Under no voltage control, left-handed or right-handed circularly polarized light passing through the liquid crystal polarization grating undergoes diffraction at the -1st or +1st order, switching to the opposite polarization state. This results in a negative or positive angular deflection in the far field. Under a certain voltage control, the liquid crystal polarization grating loses its diffraction effect, resulting in no angular deflection in the far field. The deflection angle of the liquid crystal polarization grating is determined by its phase period. By varying the phase period, liquid crystal polarization gratings with different deflection angles can be obtained.

[0060] In this embodiment, the liquid crystal polarization grating unit 12 diffracts left-handed circularly polarized light and right-handed circularly polarized light to the -1st and +1st orders, respectively. The left-handed circularly polarized light and right-handed circularly polarized light modulated with different received user communication data are deflected in opposite directions by the first and second liquid crystal polarization grating assemblies, respectively, achieving a one-to-two deflection across a wide range of discrete angles.

[0061] Based on the above-mentioned one-to-many space laser communication transmission system based on the liquid crystal phase control device, this embodiment uses it to transmit one-to-two space laser communication, and the method includes the following steps:

[0062] (1) According to the initial position information of the two receiving users and the initial position information of the one-to-many space laser communication transmission system, the initial deflection angles θ1 and θ2 corresponding to the two receiving users are analyzed, and the initial deflection angles are decomposed according to the following formula:

[0063] θ1=θ3+θ0

[0064] θ2=θ4-θ0

[0065] θ3 and θ4 are the deflection angles of the first liquid crystal optical phased array 9 and the second liquid crystal optical phased array 10 , respectively, and θ0 is the deflection angle of the liquid crystal polarization grating unit 12 .

[0066] (2) Laser 1 emits laser light and divides it into two paths: s-polarized light and p-polarized light. The first modulator 2 and the second modulator 3 modulate the communication data of different receiving users respectively. The two signals are combined into one optical signal by the polarization combiner 4 and transmitted into free space through the communication transmitting unit 5 and the transmitting mirror group 6.

[0067] (3) The fine tracking galvanometer 7 deflects the combined optical signal with high precision and enters the beam expansion unit 8 to complete the beam expansion.

[0068] (4) The angle information obtained in (1) is converted into voltage control information and loaded onto the first liquid crystal optical phased array 9 and the second liquid crystal optical phased array 10, respectively, to deflect the s-polarized light and p-polarized light in one optical signal by θ3 and θ4, respectively.

[0069] (5) The quarter-wave plate unit 11 converts the s-polarized light and the p-polarized light into left-handed circularly polarized light and right-handed circularly polarized light, which then enter the liquid crystal polarization grating unit 12 .

[0070] (6) The liquid crystal polarization grating unit 12 deflects the left-handed circularly polarized light and the right-handed circularly polarized light in opposite directions by discrete angles, and the deflection angle is θ0. At this time, the total deflection angle of the left-handed circularly polarized light is θ3+θ0, and the total deflection angle of the right-handed circularly polarized light is θ4-θ0, which are transmitted to the corresponding receiving users to complete the one-to-two transmission of communication data.

[0071] Example 2

[0072] The difference between this embodiment and the first embodiment is that:

[0073] The polarization phase control unit is formed by splicing X polarization phase control components located in the same plane perpendicular to the optical signal transmission direction, where X≥2. The polarization phase control components include a first liquid crystal optical phased array 9 and a second liquid crystal optical phased array 10 whose polarization directions are perpendicular to each other and coaxially arranged. Figure 1 As shown, the 1 / 4 wave plate unit 11 is formed by splicing X 1 / 4 wave plates located in the same plane. The liquid crystal polarization grating unit 12 is formed by splicing X liquid crystal polarization grating modules located in the same plane, and is used to realize one-to-many transmission by region and wavelength. That is, when the number of receiving users of each communication data increases to X, the polarization phase control unit, the 1 / 4 wave plate unit 11 and the liquid crystal polarization grating unit 12 are respectively divided into X regions, and each region corresponds to the deflection angle of a receiving user, so that each communication data is transmitted to X different receiving users, so that the present invention can meet the one-to-many transmission of no more than 2X receiving users. In this embodiment, the steps of transmitting communication data to 2X receiving users for one-to-many space laser communication transmission are as follows:

[0074] (1) According to the initial position information of 2X receiving users and the initial position information of the one-to-many space laser communication transmission system, the initial deflection angles θ1, θ2…, θ corresponding to the 2X receiving users are analyzed. 2X , decompose the initial deflection angle according to the following formula:

[0075] θ1=θ 1″ +θ 1'

[0076] θ2=θ 2″ -θ 1' ...

[0078] θ 2X-1 =θ (2X-1)″ +θ X'

[0079] θ2X =θ 2X″ -θ X'

[0080] Among them, θ 1″ ,...,θ (2X-1)″ is the deflection angle of the first liquid crystal optical phased array 9 corresponding to the 1st, ..., 2X-1th receiving users, θ 2″ ,...,θ 2X″ is the deflection angle of the second liquid crystal optical phased array 10 corresponding to the 2nd, ..., 2Xth receiving users, θ 1' ,...,θ x' is the deflection angle of the liquid crystal polarization barrier unit 12 .

[0081] (2) Laser 1 emits laser light and divides it into two paths: s-polarized light and p-polarized light. The first modulator 2 and the second modulator 3 modulate the communication data of different receiving users respectively. The two signals are combined into one optical signal by the polarization combiner 4 and transmitted into free space by the communication transmitting unit 5 and the transmitting mirror group 6.

[0082] (3) The fine tracking galvanometer 7 deflects the combined optical signal with high precision and enters the beam expansion unit 8 to complete the beam expansion.

[0083] (4) The angle information obtained in (1) is converted into voltage control information and loaded onto the first liquid crystal optical phased array 9 and the second liquid crystal optical phased array 10 of the X regions in the polarization phase control unit. The first liquid crystal optical phased array 9 of the X regions controls the s-polarized light to deflect θ 1″ ,...,θ (2X-1)″ , the second liquid crystal optical phased array 10 controls the p-polarized light to deflect θ 2″ ,...,θ 2X″ ;

[0084] (5) The quarter-wave plate unit 11 converts the s-polarized light and the p-polarized light into left-handed circularly polarized light and right-handed circularly polarized light, which then enter the liquid crystal polarization grating unit 12;

[0085] (6) The liquid crystal polarization grating unit 12 deflects the left-handed circularly polarized light and the right-handed circularly polarized light in opposite directions by θ 1' ,...,θ x' , at this time the total deflection angle of the left circularly polarized light is θ1, ..., θ 2X-1 , the total deflection angle of right circularly polarized light is θ2…,θ 2X , transmitted to the corresponding receiving users, completing one-to-many transmission of different communication data.

[0086] It can be seen from this that the one-to-many space laser communication transmission system based on the liquid crystal phase control device of the present invention can omit the traditional mechanical turntable and transmit different communication data one-to-many to different receiving users, thus solving the limitation that the communication system based on the liquid crystal optical phased array and the liquid crystal polarization grating can only transmit the same communication data to different receiving users. At the same time, the one-to-many transmission is achieved by polarization and region division, which greatly improves the utilization rate of the light aperture compared with the single region division method. In addition, the present invention combines the liquid crystal polarization grating and the liquid crystal optical phased array, and utilizes its phase modulation characteristics to solve the adaptation problem of the liquid crystal optical phased array and the liquid crystal polarization grating during one-to-many transmission, and realizes one-to-many arbitrary angle beam deflection within a large angle range, meeting the application requirements of space laser communication.

Claims

1. A one-to-many spatial laser communication transmission system based on a liquid crystal phase control device, characterized by: The invention comprises a laser (1), a polarization modulator unit, a polarization beam combiner (4), and a communication transmitting unit (5) connected in sequence to the output end of the laser (1), and a precision tracking galvanometer (7), a polarization phase control unit, a quarter wave plate unit (11), and a liquid crystal polarization grating unit (12) arranged in sequence along the transmission light path of the communication transmitting unit (5); The laser (1) is used to generate carrier linear polarized light and divide it into s-polarized light and p-polarized light output; The polarization modulator unit is used to load different communication data onto s-polarized light and p-polarized light respectively; The polarization beam combiner (4) is used to combine s-polarized light and p-polarized light into one optical signal output; The communication transmitting unit (5) is used to receive and transmit the combined optical signal; The fine tracking galvanometer (7) is used to adjust the angle of the combined optical signal and reflect it to the polarization phase control unit; The polarization phase control unit is used to change the modulation phase distribution to achieve continuous angular deflection of the optical signal; The quarter wave plate unit (11) is used to convert s-polarized light and p-polarized light into left-handed circularly polarized light and right-handed circularly polarized light respectively; The liquid crystal polarization grating unit (12) is used for performing discrete angle deflection on left-handed circularly polarized light and right-handed circularly polarized light, and transmitting the light to corresponding receiving users.

2. The one-to-many spatial laser communication transmission system based on a liquid crystal phase control device according to claim 1, characterized in that: The polarization phase control unit includes X polarization phase control components located in the same plane perpendicular to the optical signal transmission direction, where X≥1; The quarter wave plate unit (11) comprises X quarter wave plates arranged in one-to-one correspondence with the X polarization phase control components; The liquid crystal polarization grating unit (12) comprises X liquid crystal polarization grating modules arranged in a one-to-one correspondence with the X polarization phase regulating components.

3. The one-to-many spatial laser communication transmission system based on a liquid crystal phase control device according to claim 2, characterized in that: The polarization phase control component comprises a first liquid crystal optical phased array (9) and a second liquid crystal optical phased array (10) whose polarization directions are perpendicular to each other and are coaxially arranged; The first liquid crystal optical phased array (9) is used to modulate s-polarized light to deflect it; The second liquid crystal optical phased array (10) is used to modulate p-polarized light to deflect it.

4. The one-to-many spatial laser communication transmission system based on a liquid crystal phase control device according to claim 3 is characterized in that: The liquid crystal polarization grating module includes a first liquid crystal polarization grating component and a second liquid crystal polarization grating component, whose polarization directions are perpendicular to each other and coaxially stacked, and are used to diffract left-handed circularly polarized light and right-handed circularly polarized light respectively; The first liquid crystal polarization grating component and the second liquid crystal polarization grating component each include multiple layers of liquid crystal polarization gratings coaxially stacked.

5. The one-to-many spatial laser communication transmission system based on a liquid crystal phase control device according to claim 4 is characterized in that: The output end of the communication transmitting unit (5) is further provided with a transmitting mirror group (6) for collimating the optical signal emitted by the communication transmitting unit (5); The polarization modulator unit is connected to the laser (1) and the polarization beam combiner (4) respectively via optical fibers; The polarization beam combiner (4) and the communication transmitting unit (5) are connected via an optical fiber. The communication transmitting unit (5) transmits the optical signal through free space to the transmitting mirror group (6), which collimates the optical signal and then transmits it to the precision tracking galvanometer (7). An aperture beam expansion unit (8) for expanding the optical signal is also provided between the fine tracking galvanometer (7) and the polarization phase control unit.

6. The one-to-many spatial laser communication transmission system based on a liquid crystal phase control device according to claim 5, characterized in that: The polarization modulator unit comprises a first modulator (2) and a second modulator (3), which are used to load different communication data onto s-polarized light and p-polarized light respectively; The beam expansion unit (8) is configured as a Maksutov catadioptric system.

7. The one-to-many spatial laser communication transmission system based on a liquid crystal phase control device according to claim 2, characterized in that: The polarization phase control component includes two liquid crystal on silicon phased arrays with polarization directions perpendicular to each other and coaxially arranged, or the polarization phase control component includes two MEMS phased arrays with polarization directions perpendicular to each other and coaxially arranged.

8. A one-to-many space laser communication transmission method based on a liquid crystal phase control device, based on the one-to-many space laser communication transmission system based on a liquid crystal phase control device according to any one of claims 1-7, characterized in that: The following steps are involved: S1. According to the initial position information of the receiving user and the initial position information of the one-to-many space laser communication transmission system, the initial deflection angle of the corresponding receiving user is analyzed, and the initial deflection angle is decomposed into the deflection angle of the corresponding polarization phase control unit and the deflection angle of the corresponding liquid crystal polarization grating unit (12); S2. The laser (1) emits laser light and separates it into s-polarized light and p-polarized light. The polarization modulator unit loads different communication data onto the s-polarized light and p-polarized light, respectively. The light is then combined into one optical signal by the polarization combiner (4) and transmitted by the communication transmitting unit (5). S3. Fine tracking galvanometer (7) deflects the light signal; S4. The deflection angle of the polarization phase control unit corresponding to step S1 is converted into voltage control information, loaded into the polarization phase control unit, and controls the s-polarized light and p-polarized light in one optical signal to deflect to corresponding angles respectively; The S5.1 / 4 wave plate unit (11) converts s-polarized light and p-polarized light into left-handed circularly polarized light and right-handed circularly polarized light; S6. The liquid crystal polarization grating unit (12) deflects the left-handed circularly polarized light and the right-handed circularly polarized light in opposite directions at discrete angles and transmits them to corresponding receiving users, thereby completing one-to-many transmission of different communication data.

9. The one-to-many spatial laser communication transmission method based on a liquid crystal phase control device according to claim 8, characterized in that: In step S1, the number of receiving users is 2X, where X≥1, and the initial deflection angles of the corresponding receiving users are recorded as θ1, θ2…, θ 2X The polarization phase control unit includes X polarization phase control components located in the same plane, and the polarization phase control components include a first liquid crystal optical phased array (9) and a second liquid crystal optical phased array (10) whose polarization directions are perpendicular to each other and coaxially arranged; the initial deflection angle is decomposed according to the following formula: θ1=θ 1" +θ 1' θ2=θ 2" -θ 1' ... i 2X-1 =θ (2X-1)" +θ X' i 2X =θ 2X" -θ X' Among them, θ 1" ,...,θ (2X-1)" is the deflection angle of the first liquid crystal optical phased array (9) corresponding to the 1st, ..., 2X-1th receiving users, θ 2" ,...,θ 2X" is the deflection angle of the second liquid crystal optical phased array (10) corresponding to the 2nd, ..., 2Xth receiving users, θ 1' ,...,θ x' is the deflection angle of the liquid crystal polarization grating unit (12).

10. The one-to-many spatial laser communication transmission method based on a liquid crystal phase control device according to claim 8, characterized in that: Step S4 is specifically as follows: converting the deflection angle of the polarization phase control unit corresponding to step S1 into voltage control information, and loading it onto the first liquid crystal optical phased array (9) and the second liquid crystal optical phased array (10) of the X regions in the polarization phase control unit, respectively. The first liquid crystal optical phased array (9) of the X regions controls the s-polarized light to deflect θ 1" ,...,θ (2X-1)" , the second liquid crystal optical phased array (10) controls the p-polarized light to deflect θ 2" ,...,θ 2X" .

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