Optical polarization state synchronization device, terminal, access point device and space optical communication system

Abstract

The present application provides an optical polarization state synchronization device, a terminal, an access point device, and a space optical communication system. The optical polarization state synchronization device includes: an optical path conversion component, a first polarization controller, a second polarization controller, and a first photodetector. The optical path conversion component transmits the first polarization light and the second polarization light to the first polarization controller; the first polarization controller is used to adjust itself under the control of an electrical signal when receiving only the first polarization light, so that the optical power of the first polarization light detected by the first photodetector meets the optical polarization state synchronization condition; the second polarization controller is used to adjust itself under the control of an electrical signal when the first polarization controller only receives the second polarization light, so that the optical power of the second polarization light detected by the first photodetector meets the optical polarization state synchronization condition. By controlling the polarization state synchronization of the first polarization light and the second polarization light, the time delay of the polarization control process is reduced, and the complexity of the space optical communication system is reduced.

Description

Technical Field

[0001] The present application relates to the field of space optical communication technology, and in particular to an optical polarization state synchronization device, a terminal, an access point device, and a space optical communication system. Background Art

[0002] Space optical communication technology is a new communication technology that simultaneously shares the high bandwidth of optical fiber and wireless mobility. It is an important method for real-time access in indoor areas, offices, and campuses. Compared to space optical communication systems that use mechanical beam deflection controllers, systems that use non-mechanical beam deflection controllers such as liquid crystal on silicon (LCoS), liquid crystal polarization gratings (LCPG), and liquid crystal wedges offer multiple advantages, including miniaturization, ease of integration, and the ability to multiplex user communications. However, non-mechanical beam deflection controllers such as LCoS, LCPG, and LC wedges are polarization-sensitive devices, meaning they limit the polarization state of the light that can operate on them. Therefore, to minimize light loss when passing through these non-mechanical beam deflection controllers and optimize the performance of space optical communication systems, polarization control of the light passing through these non-mechanical beam deflection controllers is necessary.

[0003] A spatial optical communication system can include an access point device and a terminal. Information exchange between the access point and the terminal is achieved by sending downlink light from the access point device to the terminal, and from the terminal to the access point device. The access point device typically includes a non-mechanical beam deflection controller. To minimize light loss when passing through the non-mechanical beam deflection controller, polarization control of the uplink and downlink light is required. In related technologies, this requires separate polarization control for both uplink and downlink light, which results in significant latency, impacting the response speed of information exchange. Summary of the Invention

[0004] Embodiments of the present application provide an optical polarization state synchronization device, a terminal, an access point device, and a spatial optical communication system to reduce the time delay of a polarization control process.

[0005] In a first aspect, an embodiment of the present application provides an optical polarization state synchronization device, which may include: an optical path conversion component, a first polarization controller located on the light-emitting side of the optical path conversion component, a second polarization controller located on the light-incoming side of the optical path conversion component, and a first photodetector located on the light-emitting side of the first polarization controller; wherein the optical path conversion component is used to receive first polarized light and second polarized light, and transmit the received first polarized light and second polarized light to the first polarization controller; when the first polarization controller only receives the first polarized light, it adjusts itself under the control of an electrical signal so that the optical power of the first polarized light detected by the first photodetector meets the optical polarization state synchronization condition; when the first polarization controller only receives the second polarized light, the second polarization controller is used to adjust itself under the control of an electrical signal so that the optical power of the second polarized light detected by the first photodetector meets the optical polarization state synchronization condition.

[0006] In an embodiment of the present application, an optical path conversion component, a first polarization controller, a second polarization controller, and a first photodetector are provided in the optical polarization state synchronization device. The first polarization controller performs polarization control on the first polarized light, and the second polarization controller performs polarization control on the second polarized light. This allows the polarization states of the first polarized light and the second polarized light to be synchronized without detecting the polarization states of the first polarized light and the second polarized light. In this way, when polarization control is performed on the first polarized light and the second polarized light, only one of the first polarized light and the second polarized light needs to be polarized to achieve polarization control of the first polarized light and the second polarized light, so that the first polarized light and the second polarized light can operate in an optimal state when passing through the beam deflection controller in the space optical communication system. Furthermore, the polarization control process can be simplified, the time delay of the polarization control process can be effectively reduced, and the response speed of information exchange can be improved. In addition, the structure of the space optical communication system can be simplified, and the system complexity can be reduced.

[0007] In one possible implementation of the present application, the optical polarization state synchronization device may further include: an optical path selection component located on the light-entry side of the first polarization controller; the optical path selection component is configured to block the second polarized light and transmit the first polarized light, so that the first polarization controller receives only the first polarized light; or the optical path selection component is configured to block the first polarized light and transmit the second polarized light, so that the first polarization controller receives only the second polarized light. During synchronization of the first polarized light and the second polarized light, the optical path selection component may be used to control the light received by the first polarization controller.

[0008] In a possible implementation of the present application, the above-mentioned optical path conversion component may include: a first beam splitter, a second beam splitter located between the first beam splitter and the first polarization controller, and a reflection component; the first beam splitter is used to receive the first polarized light, split the received first polarized light into a first sub-polarized light and a second sub-polarized light, reflect the first sub-polarized light to the second beam splitter, and transmit the second sub-polarized light; the second beam splitter is used to transmit the received first sub-polarized light to the first polarization controller; the first beam splitter is also used to receive the second polarized light, split the received second polarized light into a third sub-polarized light and a fourth sub-polarized light, reflect the third sub-polarized light to the reflection component, and transmit the fourth sub-polarized light; the reflection component is used to reflect the received third sub-polarized light to the second beam splitter; the second beam splitter is also used to reflect the received third sub-polarized light to the first polarization controller.

[0009] In an embodiment of the present application, by setting a first spectroscope, the first polarized light can be split into two beams of light, one of which can continue to be transmitted to the optical transceiver, and the other beam of light can be used in the polarization control process of the first polarized light. In addition, the first spectroscope can also split the second polarized light into two beams of light, one of which can continue to be transmitted to the access point device, and the other beam of light can be used in the polarization control process of the second polarized light. In an embodiment of the present application, by setting a first spectroscope to split the first polarized light and the second polarized light, the optical path of the optical polarization state synchronization device can be made more compact and the complexity of the optical path can be reduced. Of course, when specifically setting the optical path of the optical polarization state synchronization device, two spectroscopes can also be set to split the first polarized light and the second polarized light respectively, or other optical components can be used to split the first polarized light and the second polarized light. The specific setting of the optical path is not limited here. By setting a second beam splitter, the first sub-polarized light and the third sub-polarized light can be transmitted to the first polarization controller, and the optical path of the optical polarization state synchronization device can be made more compact, reducing the complexity of the optical path. Of course, two optical components can also be used to transmit the first sub-polarized light and the third sub-polarized light to the first polarization control respectively. The specific setting of the optical path is not limited here.

[0010] Optionally, in an embodiment of the present application, the above-mentioned reflective component may include: a first reflector located on the optical path of the first reflector, a second reflector located on the optical path of the first reflector, and a third reflector located on the optical path of the second reflector; the first reflector is located on a side of the first reflector away from the first polarization controller in the first direction, and is used to receive the third sub-polarized light reflected by the first reflector and reflect the received third sub-polarized light to the second reflector; the first direction is the direction in which the first polarization controller points to the first reflector; the second reflector is located on a side of the first reflector in the second direction, and is used to reflect the received third sub-polarized light to the third reflector; the second direction is a direction perpendicular to the first direction; the second reflector and the third reflector are located on both sides of the first reflector in the first direction, and the second reflector and the third reflector are located on the same side of the first reflector in the second direction; the third reflector is used to reflect the received third sub-polarized light to the second reflector. In practical applications, the reflective component can also be implemented in other ways. For example, the reflective component can be a free-form surface mirror. The specific implementation method of the reflective component is not limited here.

[0011] In one possible implementation of the present application, the optical path selection component may include: a first optical switch and a second optical switch, wherein the first optical switch is located between the first beam splitter and the second beam splitter, and the second optical switch is located between the third reflector and the second beam splitter. Because the third sub-polarized light and the first sub-polarized light emitted by the first beam splitter are transmitted to the second beam splitter via different paths, the first optical switch is located on the optical path that transmits the first sub-polarized light. When the first optical switch is turned on, the first sub-polarized light can pass through the first optical switch and the second beam splitter and be emitted to the first polarization controller. When the first optical switch is turned off, the first sub-polarized light cannot be emitted to the first polarization controller. The second optical switch is located on the optical path that transmits the third sub-polarized light. When the second optical switch is turned on, the third sub-polarized light can pass through the second optical switch and the second beam splitter and be emitted to the first polarization controller. When the second optical switch is turned off, the third sub-polarized light cannot be emitted to the first polarization controller. Furthermore, the second optical switch may be located elsewhere, for example, between the second reflector and the third reflector. Any optical switch located on the optical path that transmits only the third sub-polarized light is not limited here.

[0012] In one possible implementation of the present application, the first polarization controller may be an electrically controlled polarizer, which is used to rotate the direction of its optical axis under the control of an electrical signal. Furthermore, the first polarization controller may also be other optical components. For example, the first polarization controller may include an electrically controlled quarter-wave plate and an electrically controlled half-wave plate; or the first polarization controller may include a first electrically controlled quarter-wave plate, a second electrically controlled quarter-wave plate, and an electrically controlled half-wave plate, with the electrically controlled half-wave plate positioned between the first and second electrically controlled quarter-wave plates. The specific implementation of the first polarization controller is not limited herein.

[0013] In one embodiment of the present application, the above-mentioned second polarization controller may include: an electrically controlled quarter-wave plate, and an electrically controlled half-wave plate located on the optical path of the electrically controlled quarter-wave plate, wherein the electrically controlled quarter-wave plate is used to rotate the direction of its own optical axis under the control of an electrical signal, and the electrically controlled half-wave plate is used to rotate the direction of its own optical axis under the control of an electrical signal.

[0014] In another embodiment of the present application, the above-mentioned second polarization controller may include: a first electrically controlled quarter wave plate, a second electrically controlled quarter wave plate, and an electrically controlled half wave plate; the electrically controlled half wave plate is located between the first electrically controlled quarter wave plate and the second electrically controlled quarter wave plate, the first electrically controlled quarter wave plate is used to rotate the direction of its own optical axis under the control of an electrical signal, the second electrically controlled quarter wave plate is used to rotate the direction of its own optical axis under the control of an electrical signal, and the electrically controlled half wave plate is used to rotate the direction of its own optical axis under the control of an electrical signal.

[0015] In specific implementation, the specific structure of the second polarization controller in the embodiment of the present application can also be realized by other means. For example, the second polarization controller can also adopt an electrically controlled polarizer. The specific structure of the second polarization controller is not limited here.

[0016] In one possible implementation of the present application, the optical polarization state synchronization device may further include a first lens located between the first polarization controller and the first photodetector. The first lens may converge light emitted by the first polarization controller, thereby making the optical power of the light detected by the first photodetector more accurate.

[0017] In practical applications, to control the various optical components in the terminal, the optical polarization state synchronization device in the embodiments of the present application may further include: a processor electrically connected to the first polarization controller, the second polarization controller, and the first photodetector. The processor is configured to, when the first polarization controller receives only the first polarization light, control the first polarization controller via an electrical signal to adjust itself so that the optical power of the first polarization light detected by the first photodetector meets the optical polarization state synchronization condition; and, when the first polarization controller receives only the second polarization light, control the second polarization controller via an electrical signal to adjust itself so that the optical power of the second polarization light detected by the first photodetector meets the optical polarization state synchronization condition. In other words, the processor can control the first polarization controller and the second polarization controller via electrical signals to polarize the first and second polarization lights, thereby achieving polarization state synchronization between the first and second polarization lights.

[0018] In a second aspect, an embodiment of the present application further provides a terminal of a space optical communication system, which may include: any of the above-mentioned optical polarization state synchronization devices, an optical transceiver, and a fiber collimator located on the optical path of the optical transceiver.

[0019] The optical transceiver is used to receive the second sub-polarized light transmitted by the first beam splitter in the optical polarization state synchronization device. The second sub-polarized light is obtained by the first beam splitter splitting the first polarized light emitted by the access point device. In other words, a portion of the first polarized light emitted by the access point device (i.e., the second sub-polarized light) is ultimately emitted to the optical transceiver of the terminal, thereby enabling the access point device to transmit optical communication information to the terminal.

[0020] The optical transceiver can also be used to emit a second polarized light. The fiber collimator can be used to collimate the second polarized light emitted by the optical transceiver and transmit the collimated second polarized light to the optical polarization state synchronization device. After the second polarized light is split by the first beamsplitter in the optical polarization state synchronization device, the resulting fourth polarized light can be emitted to the access point device after transmitting several meters in free space. After passing through the reflective silicon-based liquid crystal, polarization controller, and fiber collimator in the access point device, it is emitted to the optical transceiver. In other words, a portion of the second polarized light emitted by the terminal (i.e., the fourth polarized light) is ultimately emitted to the optical transceiver in the access point device, enabling the transmission of optical communication information from the terminal to the access point device.

[0021] In an embodiment of the present application, by providing an optical polarization state synchronization device in the terminal, the first polarized light and the second polarized light can be synchronized on the terminal side. When performing polarization control on the first polarized light and the second polarized light, only one of the first polarized light and the second polarized light needs to be polarized to achieve polarization control of the first polarized light and the second polarized light, so that the first polarized light and the second polarized light can operate in an optimal state when passing through the beam deflection controller in the spatial optical communication system. Furthermore, the polarization control process can be simplified, the time delay of the polarization control process can be effectively reduced, and the response speed of information exchange can be improved.

[0022] In one possible implementation of the present application, the terminal may further include a two-dimensional rotating platform. The two-dimensional rotating platform is used to support optical components in the terminal, such as an optical path conversion assembly, a first polarization controller, a second polarization controller, a first photodetector, an optical transceiver, and a fiber collimator. The two-dimensional rotating platform is used to adjust the direction of the fourth sub-polarized light transmitted by the first beam splitter so that the second polarized light (i.e., the fourth sub-polarized light) ultimately emitted by the terminal is directed toward the access point device, thereby enabling optical communication between the terminal and the access point device.

[0023] In another embodiment of the present application, the optical polarization state synchronization device may further include a galvanometer located in the optical path of the optical path conversion component. The galvanometer is configured to receive the fourth sub-polarized light transmitted by the first beam splitter and adjust itself under the control of an electrical signal to change the emission direction of the fourth sub-polarized light.

[0024] In another embodiment of the present application, the above-mentioned optical polarization state synchronization device may further include: a third beam splitter, a reflective silicon-based liquid crystal, a third polarization controller, and a second photodetector, wherein the reflective silicon-based liquid crystal is used to receive the second polarized light emitted by the optical transceiver and reflect the received second polarized light to the third beam splitter; the third beam splitter is used to receive the second polarized light and reflect part of the second polarized light to the second photodetector, and the other part of the second polarized light is transmitted to the optical path conversion component in the optical polarization state synchronization device; the third polarization controller is located on the light incident side of the second photodetector, and is used to adjust itself under the control of an electrical signal according to the optical power of the second polarized light detected by the second photodetector, so that the optical power of the second polarized light detected by the second photodetector meets the set conditions.

[0025] By providing a third beam splitter, the second polarized light can be split into two beams, one of which is transmitted to the access point device, while the other can be used for polarization control of the second polarized light. By providing a third polarization controller and a second photodetector, polarization control of the second polarized light can be performed on the terminal side, increasing the number of polarization controls on the second polarized light and improving the accuracy of polarization control of the first polarized light and the second polarized light in the optical communication system, allowing the first polarized light and the second polarized light to operate in an optimal state at the beam deflection controller. Of course, since the terminal can perform polarization control on the second polarized light, and the polarization states of the first polarized light and the second polarized light can be synchronized in the terminal, the optical components in the access point device that perform polarization control on the first polarized light can be omitted. For example, optical components such as the polarization controller, beam splitter, and photodetector in the access point device can be omitted.

[0026] Furthermore, reflective silicon-based liquid crystals can reflect second polarized light and deflect the incident second polarized light at any angle. During operation, the reflective silicon-based liquid crystals can control the deflection of the liquid crystal molecules to adjust the reflection angle of the second polarized light within a range of 0 to 90 degrees. By adjusting the reflection angle of the second polarized light through the reflective silicon-based liquid crystals, the second polarized light emitted by the terminal can be directed toward the corresponding access point device, thereby enabling optical communication between the terminal and the access point device.

[0027] In another embodiment of the present application, the above-mentioned optical polarization state synchronization device may further include: a fourth beam splitter, a liquid crystal polarization grating, a fourth polarization controller, and a third photodetector, wherein the liquid crystal polarization grating is used to receive the second polarized light emitted by the optical transceiver and transmit the received second polarized light to the fourth beam splitter; the fourth beam splitter is used to receive the second polarized light and reflect part of the second polarized light to the third photodetector, and transmit the other part of the second polarized light to the optical path conversion component in the optical polarization state synchronization device; the fourth polarization controller is located on the light incident side of the third photodetector, and is used to adjust itself under the control of an electrical signal according to the optical power of the second polarized light detected by the third photodetector, so that the optical power of the second polarized light detected by the third photodetector meets the set conditions.

[0028] The liquid crystal polarization grating transmits the second polarized light and deflects the incident second polarized light at any angle. When the liquid crystal polarization grating is in operation, the deflection of the liquid crystal molecules can be controlled to adjust the output angle of the second polarized light within a range of 0 to 90 degrees. By adjusting the output angle of the second polarized light through the liquid crystal polarization grating, the second polarized light emitted by the terminal is directed toward the corresponding access point device, thereby enabling optical communication between the terminal and the access point device.

[0029] In a third aspect, an embodiment of the present application further provides an access point device in a space optical communication system, the access point device comprising: any one of the above-mentioned optical polarization state synchronization devices.

[0030] In a fourth aspect, embodiments of the present application further provide a spatial optical communication system, comprising: a terminal and an access point device. The terminal may include any of the aforementioned optical polarization state synchronization devices; and / or the access point device may include any of the aforementioned optical polarization state synchronization devices.

[0031] In another embodiment of the present application, the terminal may be any terminal in the second aspect described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram for comparison of several polarization states;

[0033] Figure 2 Schematic diagram of the relationship between polarized light and beam deflection controller;

[0034] Figure 3 Schematic diagram of the structure of a space optical communication system in the related art;

[0035] Figure 4 This is a schematic structural diagram of the optical polarization state synchronization device in an embodiment of the present application;

[0036] Figure 5 A schematic diagram of the structure of a spatial optical communication system provided in an embodiment of the present application;

[0037] Figure 6 Another structural diagram of the spatial optical communication system provided in an embodiment of the present application;

[0038] Figure 7 Another structural diagram of the spatial optical communication system provided in an embodiment of the present application;

[0039] Figure 8 Another structural diagram of the spatial optical communication system provided in an embodiment of the present application;

[0040] Figure 9 This is another structural diagram of the spatial optical communication system provided in an embodiment of the present application.

[0041] Reference numerals:

[0042] 200 - Optical polarization state synchronization device; 20 - Terminal; 21 - Optical path conversion component; 211 - First beam splitter; 212 - Second beam splitter; 213a - First reflector; 213b - Second reflector; 213c - Third reflector; 22 - First polarization controller; 23 - Second polarization controller; 24 - First photodetector; 25 - Optical path selection component; 251 - First optical switch; 252 - Second optical switch; 26 - First lens; 27 - Optical transceiver in the terminal; 28 - Fiber collimator in the terminal; 29 - Two-dimensional rotating platform; 210 - Galvanometer; 30 - Access point device; 31 -Optical transceiver in the access point device; 32-Fiber optic collimator in the access point device; 33-Polarization controller in the access point device; 34-Reflective silicon-based liquid crystal in the access point device; 35-Photodetector in the access point device; 36-Lens in the access point device; 37-Beam splitter in the access point device; 401-Third beam splitter; 402-Reflective silicon-based liquid crystal; 403-Third polarization controller; 404-Second photodetector; 405-Second lens; 406-Fourth beam splitter; 407-Liquid crystal polarization grating; 408-Fourth polarization controller; 409-Third photodetector. DETAILED DESCRIPTION

[0043] In order to more clearly illustrate the embodiments of the present application, several polarization states of light are first introduced. Figure 1 is a schematic diagram for the comparison of several polarization states, such as Figure 1 As shown, the polarization state of light can be divided into linearly polarized light, elliptically polarized light and circularly polarized light. In the figure, Ex is the slow axis direction, Ey is the fast axis direction, and z is the propagation direction of light. Polarized light can be divided into fast light and slow light along the fast axis Ey direction and the slow axis Ex direction. For linearly polarized light, if the phase difference △ between fast light and slow light is 0° or 180°, then the light synthesized by fast light and slow light is linearly polarized, and thus is called linearly polarized light. For circularly polarized light, if the phase difference △ between fast light and slow light is ±90°, then the light synthesized by fast light and slow light is circularly polarized, and thus is called circularly polarized light. For elliptically polarized light, if the phase difference △ between fast light and slow light is not 0°, ±90° and 180°, then the light synthesized by fast light and slow light is elliptically polarized, and thus is called elliptically polarized light.

[0044] Figure 2 is a schematic diagram of the relationship between polarized light and the beam deflection controller, as shown in Figure 2As shown in the figure, the first polarizer and the second polarizer are beam deflection controllers, wherein the double-headed arrow in the first polarizer indicates the transmission axis direction of the first polarizer. In the figure, the transmission axis direction of the first polarizer is taken as the vertical direction as an example. The double-headed arrow in the second polarizer indicates the transmission axis direction of the second polarizer. In the figure, the transmission axis direction of the second polarizer is taken as the horizontal direction as an example. That is to say, the transmission axis direction of the first polarizer and the transmission axis direction of the second polarizer are perpendicular to each other. When omnidirectional polarized light passes through the first polarizer, only polarized light with the same vibration direction as the transmission axis direction of the first polarized light can pass through, thereby obtaining linearly polarized light with a vertical vibration direction. Since the vibration direction of the linearly polarized light is perpendicular to the transmission axis direction of the second polarizer, the linearly polarized light cannot pass through the second polarizer. Therefore, in order for the linearly polarized light output by the first polarizer to pass through the second polarizer without loss, the polarization of the linearly polarized light needs to be controlled.

[0045] Similarly, spatial optical communication systems have many beam deflection controllers, such as phase-type silicon-based liquid crystal, liquid crystal phased array, liquid crystal polarization grating, liquid crystal wedge, etc. These beam deflection controllers are polarization-sensitive devices. In order to minimize the loss of light when passing through these beam deflection controllers, it is necessary to set up polarization controllers in the spatial optical communication system to control the polarization of light.

[0046] Figure 3 It is a structural diagram of a space optical communication system in related technology, such as Figure 3 As shown, in related art, a spatial optical communication system may include an access point device 11 and a terminal 12. Information exchange between the access point device 11 and the terminal 12 can be achieved by the access point device 11 sending downlink light m to the terminal 12, and the terminal 12 sending uplink light n to the access point device 11. The access point device 11 may include an optical transceiver 111, a fiber collimator 112, a reflective liquid crystal on silicon 113, a polarization controller 114, photodetectors PD1 and PD2, lenses L1 and L2, a beam splitter T1, and a beam splitter T2. The terminal 12 may include an optical transceiver 121, a fiber collimator 122, and a polarization controller 123.

[0047] In the related art, the polarization of uplink light and downlink light is controlled by using the access point device 11 and the terminal 12 to jointly control the polarization. Figure 3The downlink light emitted by the optical transceiver 111 of the access point device 11 is collimated by the fiber collimator 112, passes through the polarization controller 114 and the beam splitter T2, and then is emitted to the reflective silicon liquid crystal 113. The reflective silicon liquid crystal 113 reflects the received downlink light to the beam splitter T1, which splits the downlink light into two parts. One part of the downlink light is transmitted through the beam splitter T1 and emitted to the terminal 12. The other part of the downlink light is reflected by the beam splitter T1 and transmitted through the lens L1 before being emitted to the photodetector PD1. The photodetector PD1 detects the optical power of the received downlink light. The access point device 11 determines the current polarization state of the downlink light based on the difference in optical power between two consecutive detections. Based on the current polarization state of the downlink light, the polarization controller 114 is controlled to adjust itself to change the polarization state of the downlink light, ensuring that the downlink light operates in the optimal state.

[0048] The uplink light emitted by the optical transceiver 121 of terminal 12 is collimated by the fiber collimator 122 and then passes through the polarization controller 123. After traveling several meters in free space, it is emitted to the access point 11. In the access point 11, the uplink light is transmitted through the beam splitter T1 and reflected by the reflective liquid crystal on silicon 113 before being emitted to the beam splitter T2. Beam splitter T2 splits the uplink light into two parts. One part of the uplink light is transmitted through the beam splitter T2, passes through the polarization controller 114 and the fiber collimator 112, and then is emitted to the optical transceiver 111. The other part of the uplink light is reflected by the beam splitter T2 and transmitted through the lens L2 before being emitted to the photodetector PD2. The photodetector PD2 detects the optical power of the received uplink light. However, during the regulation of the polarization state of the uplink light, it is necessary to feed back the optical power to the terminal 12 via a polarization state information feedback link between the access point device 11 and the terminal 12. The terminal 12 can then determine the current polarization state of the uplink light based on the difference in optical power obtained from two adjacent detections. The terminal 12 controls the polarization controller 123 to adjust itself based on the current polarization state of the uplink light, thereby changing the polarization state of the uplink light so that the uplink light can operate in an optimal state.

[0049] In other words, during the process of adjusting the polarization state of the uplink light, an additional polarization state information feedback link must be established between the access point device 11 and the terminal 12. This polarization state information feedback link can be an optical link, a wireless link, or other link. Furthermore, each time the terminal 12 adjusts the polarization controller 123, the access point device 11 must detect the optical power of the uplink light and feed it back to the terminal 12 via the feedback link. This adjustment process incurs a significant delay, affecting the response speed of information exchange and, in turn, limiting the mobility of the terminal 12 in the spatial optical communication system.

[0050] Based on this, in order to reduce the delay of the polarization control process in the space optical communication system, the embodiments of the present application provide an optical polarization state synchronization device, a terminal, an access point device and a space optical communication system.

[0051] In order to make the objectives, technical solutions and advantages of this application more clear, the present application will be further described in detail below with reference to the accompanying drawings. It should be noted that in this specification, similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. In addition, it should be noted that in the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0052] The spatial optical communication system provided in the embodiments of the present application can be applied to the field of high-bandwidth spatial optical communication. The spatial optical communication system can be applied to various communication networks, such as point-to-point networks, point-to-multipoint networks, and peer-to-peer networks. The embodiments of the present application illustrate the application of the spatial optical communication system to a point-to-multipoint network as an example. Specifically, the spatial optical communication system can include: an access point device and a terminal. The access point device can serve as a wireless router, and the terminal can be a mobile phone, computer, intelligent robot, or other intelligent device. Furthermore, the spatial optical communication system can be applied to various scenarios, such as offices and high-bandwidth all-optical home access.

[0053] Figure 4 FIG. 1 is a schematic diagram of the structure of the optical polarization state synchronization device in an embodiment of the present application. Figure 4 As shown, the optical polarization state synchronization device 200 in the embodiment of the present application may include: an optical path conversion component 21, a first polarization controller 22 located on the light-outgoing side of the optical path conversion component 21, a second polarization controller 23 located on the light-incoming side of the optical path conversion component 21, and a first photodetector 24 located on the light-outgoing side of the first polarization controller 22;

[0054] The optical path conversion component 21 is configured to receive the first polarized light a and the second polarized light b, and transmit the received first polarized light a and the second polarized light b to the first polarization controller 22. For example, in a space optical communication system, the first polarized light a may be downlink light emitted from an access point device to a terminal, and the second polarized light b may be uplink light emitted from the terminal to the access point device.

[0055] The first polarization controller 22 is configured to adjust itself under the control of an electrical signal when receiving only the first polarized light a, so that the optical power of the first polarized light a detected by the first photodetector 24 satisfies a light polarization state synchronization condition. In a specific implementation, the light polarization state synchronization condition may be when the light detected by the first photodetector 24 reaches a maximum value. Of course, the light polarization state synchronization condition may also be other conditions, which are not limited here.

[0056] The second polarization controller 23 is used to adjust itself under the control of the electrical signal when the first polarization controller 22 receives only the second polarized light b, so that the optical power of the second polarized light b detected by the first photodetector 24 meets the optical polarization state synchronization condition.

[0057] In an embodiment of the present application, an optical path conversion component, a first polarization controller, a second polarization controller, and a first photodetector are provided in the optical polarization state synchronization device. The first polarization controller performs polarization control on the first polarized light, and the second polarization controller performs polarization control on the second polarized light. This allows the polarization states of the first polarized light and the second polarized light to be synchronized without detecting the polarization states of the first polarized light and the second polarized light. In this way, when polarization control is performed on the first polarized light and the second polarized light, only one of the first polarized light and the second polarized light needs to be polarized to achieve polarization control of the first polarized light and the second polarized light, so that the first polarized light and the second polarized light can operate in an optimal state when passing through the beam deflection controller in the space optical communication system. Furthermore, the polarization control process can be simplified, the time delay of the polarization control process can be effectively reduced, and the response speed of information exchange can be improved. In addition, the structure of the space optical communication system can be simplified, and the system complexity can be reduced.

[0058] Figure 5 This is a schematic diagram of the structure of the spatial optical communication system provided in the embodiment of the present application, such as Figure 5 As shown, the spatial optical communication system may include: an access point device 30 and a terminal 20. The access point device 30 sends a first polarized light to the terminal 20, and the terminal 20 sends a second polarized light to the access point device 30, so that information interaction can be achieved between the access point device 30 and the terminal 20. Optionally, the first polarized light and the second polarized light can be non-visible light, such as infrared light.

[0059] Continue to refer to Figure 5 In an embodiment of the present application, the above-mentioned optical polarization state synchronization device 200 can be set in the terminal 20 of the spatial optical communication system, that is, the terminal 20 can include: an optical path conversion component 21, a first polarization controller 22, a second polarization controller 23 and a first photodetector 24 and other optical components.

[0060] The access point device 30 may include an optical transceiver 31, a fiber collimator 32, a polarization controller 33, a reflective liquid crystal on silicon (LCS) 34, a photodetector 35, a lens 36, and a beam splitter 37. The first polarized light emitted by the optical transceiver 31 is collimated by the fiber collimator 32, passes through the polarization controller 33, and then is emitted toward the reflective LCS 34. The reflective LCS 34 reflects the received first polarized light toward the beam splitter 37. The beam splitter 37 splits the first polarized light into two parts. One part of the first polarized light is transmitted through the beam splitter 37 and emitted toward the terminal 20. The other part of the first polarized light is reflected by the beam splitter 37 and transmitted through the lens 36 before being emitted toward the photodetector 35. The lens 36 can converge the first polarized light, making the detection results of the photodetector 35 more accurate. The photodetector 35 can detect the optical power of the received first polarized light. The access point device 30 can determine the current polarization state of the first polarized light based on the difference in optical power obtained from two adjacent detections. The polarization controller 33 is controlled to adjust itself based on the current polarization state of the first polarized light to change the polarization state of the first polarized light so that the first polarized light can operate in an optimal state when passing through the reflective silicon-based liquid crystal 34.

[0061] Optionally, each access point device 30 can exchange information with at least one terminal 20. The reflective silicon liquid crystal 34 can reflect the first polarized light and deflect the incident first polarized light at any angle. For example, if the incident angle of the first polarized light received by the reflective silicon liquid crystal 34 is 30°, when the reflective silicon liquid crystal 34 is not operating, the reflection angle of the first polarized light emitted by the reflective silicon liquid crystal 34 is 30°. When the reflective silicon liquid crystal 34 is operating, the reflection angle of the first polarized light can be adjusted within a range of 0 to 90° by controlling the deflection of the liquid crystal molecules. Thus, by adjusting the reflection angle of the first polarized light through the reflective silicon liquid crystal 34, the access point device 30 can direct the first polarized light toward the corresponding terminal 20. Here, the beam deflection controller in the space optical communication system is a reflective silicon-based liquid crystal in the access point device 30 as an example for explanation. In actual applications, other beam deflection controllers can also be used in the space optical communication system, and the beam deflection controller can be located in the access electrical device, or the beam deflection controller can also be located in the terminal, which is not limited here.

[0062] According to the time reversal principle, the polarization state change of the first polarized light emitted by the access point device's beam deflection controller toward the terminal is the inverse of the polarization state change of the second polarized light emitted by the terminal toward the access point device's beam deflection controller. In embodiments of the present application, the polarization states of the first polarized light and the second polarized light are synchronized in the terminal, and the polarization control of the first polarized light is performed in the access point device. This ensures that the polarization states of the first polarized light and the second polarized light are consistent at the access point device's beam deflection controller, and ensures that the first polarized light and the second polarized light operate in an optimal state when passing through the access point device's beam deflection controller. In other words, by controlling the synchronization of the first polarized light and the second polarized light in the terminal, the polarization state of the second polarized light in the access point device can be remotely controlled. Therefore, compared to the related art in which the polarization of the first polarized light and the second polarized light is controlled by the joint polarization control of the access point device and the terminal, in the embodiment of the present application, the polarization control of the second polarized light can be completed completely independently in the terminal, without the need to establish a polarization state information feedback link between the access point device and the terminal. This can significantly reduce the delay of the polarization control process in the space optical communication system, thereby not limiting the mobility of the terminals in the space optical communication system. Furthermore, the space optical communication system can also be applied to point-to-multipoint topology (P2MP) scenarios under the passive optical network (PON) architecture.

[0063] In practical applications, during an adjustment process before a terminal and an access point device communicate, the polarizations of the first polarized light and the second polarized light can be synchronized so that the first polarized light and the second polarized light can operate in an optimal state when passing through a beam deflection controller of the access point device, thereby improving subsequent information interaction between the terminal and the access point device.

[0064] exist Figure 5 In the spatial optical communication system shown, polarization control of the first polarized light in the access point device is used as an example for explanation. In actual applications, other methods can also be used to polarize the first polarized light or the second polarized light. For example, polarization control of the second polarized light can also be performed in the terminal. The specific setting method of the polarization control is not limited here.

[0065] Optionally, combined Figure 4 and Figure 5The optical polarization state synchronization device 200 in the embodiment of the present application may further include: an optical path selection component 25 located on the light incident side of the first polarization controller 22. The optical path selection component 25 can be used to block the second polarized light and transmit the first polarized light, so that the first polarization controller 22 only receives the first polarized light; or, the optical path selection component 25 can be used to block the first polarized light and transmit the second polarized light, so that the first polarization controller 22 only receives the second polarized light. During the synchronization process of the first polarized light and the second polarized light, the optical path selection component 25 can be controlled to block the second polarized light and transmit the first polarized light, so that the first polarization controller 22 only receives the first polarized light. At this time, the first polarization controller 22 is controlled by an electrical signal to adjust itself so that the optical power of the first polarized light detected by the first photodetector 24 meets the optical polarization state synchronization condition. Then, the optical path selection component 25 is controlled to block the first polarized light and transmit the second polarized light, so that the first polarization controller 22 only receives the second polarized light. At this time, the second polarization controller 23 is controlled by an electrical signal to adjust itself so that the optical power of the second polarized light detected by the first photodetector 24 meets the optical polarization state synchronization condition, thereby achieving polarization state synchronization between the first polarized light and the second polarized light in the terminal. Optionally, the second polarization controller 23 can adjust itself based on the optical power of the second polarized light fed back by the first photodetector 24, thereby making the adjustment process of the second polarization controller 23 faster.

[0066] In the examples of this application, continue to refer to Figure 4 and Figure 5 , the optical polarization state synchronization device 200 may further include: a first lens 26 located between the first polarization controller 22 and the first photodetector 24. The first lens 26 can converge the light emitted by the first polarization controller 22, so that the optical power of the light detected by the first photodetector 24 is more accurate. In practical applications, the terminal may further include: an optical transceiver 27, and a fiber collimator 28 located on the optical path of the optical transceiver 27. The optical transceiver 27 can be used to receive the first polarized light transmitted by the optical polarization state synchronization device 200 or emit the second polarized light, and the fiber collimator 28 can be used to collimate the second polarized light emitted by the optical transceiver 27 and transmit the collimated second polarized light to the optical polarization state synchronization device 200.

[0067] In specific implementation, Figure 4 and Figure 5As shown, in some embodiments of the present application, the optical path conversion component 21 may include: a first beam splitter 211, a second beam splitter 212 located between the first beam splitter 211 and the first polarization controller 22, and a reflection component. The first beam splitter 211 may be configured to receive the first polarized light a, split the received first polarized light a into a first sub-polarized light a1 and a second sub-polarized light a2, reflect the first sub-polarized light a1 to the second beam splitter 212, and transmit the second sub-polarized light a2. The second beam splitter 212 may be configured to transmit the received first sub-polarized light a1 to the first polarization controller 22. The second sub-polarized light a2 transmitted by the first beam splitter 211 passes through the fiber collimator 28 and is then emitted to the optical transceiver 27. In other words, a portion of the first polarized light emitted by the access point device 30 (i.e., the second sub-polarized light a2) is ultimately emitted to the optical transceiver 27 of the terminal 20, enabling the access point device 30 to transmit optical communication information to the terminal 20.

[0068] In addition, the first beam splitter 211 can also be used to receive the second polarized light b, split the received second polarized light b into a third sub-polarized light b1 and a fourth sub-polarized light b2, reflect the third sub-polarized light b1 to the reflective assembly, and transmit the fourth sub-polarized light b2. The reflective assembly can be used to reflect the received third sub-polarized light b1 to the second beam splitter 212, and the second beam splitter 212 can also be used to reflect the received third sub-polarized light b1 to the first polarization controller 22. The fourth sub-polarized light b2 transmitted by the first beam splitter 211 can then be emitted to the access point device 30 after transmitting several meters in free space. After passing through the reflective silicon liquid crystal 34, polarization controller 33, and fiber collimator 32 in the access point device 30, it is emitted to the optical transceiver 31. In other words, a portion of the second polarized light emitted by the terminal 20 (i.e., the fourth sub-polarized light b2) is ultimately emitted to the optical transceiver 31 in the access point device 30, enabling the transmission of optical communication information from the terminal 20 to the access point device 30.

[0069] Continue to refer to Figure 4 and Figure 5 In the embodiments of the present application, by synchronizing the first polarized light and the second polarized light and performing polarization control on either the first polarized light or the second polarized light, the first polarized light and the second polarized light can be optimized when passing through the beam deflection controller in the spatial optical communication system (for example, when passing through the reflective liquid crystal on silicon 34 in the access device 30). Furthermore, the optical loss of the second sub-polarized light a2 ultimately emitted by the access point device 30 to the optical transceiver 27 in the terminal 20, and the fourth sub-polarized light b2 ultimately emitted by the terminal 20 to the optical transceiver 31 in the access point device 30, can be minimized. This increases the optical signal strength between the access point device 30 and the terminal 20, resulting in enhanced optical communication interaction.

[0070] In the embodiment of the present application, by setting the first beam splitter 211, the first polarized light a can be split into two beams of light, one of which can continue to be transmitted to the optical transceiver 27, and the other beam of light can be used in the polarization control process of the first polarized light. In addition, the first beam splitter 211 can also split the second polarized light b into two beams of light, one of which can continue to be transmitted to the access point device 30, and the other beam of light can be used in the polarization control process of the second polarized light. In the embodiment of the present application, by setting the first beam splitter 211 to split the first polarized light and the second polarized light, the optical path of the optical polarization state synchronization device can be made more compact and the complexity of the optical path can be reduced. Of course, when specifically setting the optical path of the optical polarization state synchronization device, two beam splitters can also be set to split the first polarized light and the second polarized light respectively, or other optical components can be used to split the first polarized light and the second polarized light. The specific setting of the optical path is not limited here. By setting the second beam splitter 212, the first sub-polarized light a1 and the third sub-polarized light b1 can be transmitted to the first polarization controller 22, and the optical path of the optical polarization state synchronization device can be made more compact, reducing the complexity of the optical path. Of course, two optical components can also be used to transmit the first sub-polarized light a1 and the third sub-polarized light b1 to the first polarization controller 22 respectively. The specific setting of the optical path is not limited here.

[0071] Optionally, continue with reference to Figure 4 and Figure 5 The reflective assembly may include a first reflector 213a located on the optical path of the first beam splitter 211, a second reflector 213b located on the optical path of the first reflector 213a, and a third reflector 213c located on the optical path of the second reflector 213b. The first reflector 213a may be configured to receive the third sub-polarized light b1 reflected by the first beam splitter 211 and reflect the received third sub-polarized light b1 to the second reflector 213b. The second reflector 213b may be configured to reflect the received third sub-polarized light b1 to the third reflector 213c. The third reflector 213c may be configured to reflect the received third sub-polarized light b1 to the second beam splitter 212. That is to say, by setting the first reflector 213a, the second reflector 213b and the third reflector 213c, the third sub-polarized light b1 emitted by the first beam splitter 211 can be transmitted to the second beam splitter 212, and the third sub-polarized light b1 and the first sub-polarized light a1 emitted by the first beam splitter 211 are transmitted to the second beam splitter 212 through different paths, so that the optical path selection component 25 blocks the first polarized light and the second polarized light respectively, so that the first polarization controller 22 can only receive the second polarized light or only receive the first polarized light.

[0072] The first reflector 213a is located on a side of the first beam splitter 211 away from the first polarization controller 22 in a first direction F1, where the first direction F1 may be the direction from the first polarization controller 22 to the first beam splitter 211. The second reflector 213b is located on a side of the first reflector 213a in a second direction F2, where the second direction F2 may be a direction perpendicular to the first direction F1. The second reflector 213b and the third reflector 213c are located on either side of the first beam splitter 211 in the first direction F1, and are located on the same side of the first beam splitter 211 in the second direction F2.

[0073] In practical applications, the reflective component may also be implemented in other ways. For example, the reflective component may be a free-form surface mirror. The specific implementation method of the reflective component is not limited here.

[0074] In the embodiments of this application, Figure 4 and Figure 5 As shown, the optical path selection component 25 may include a first optical switch 251 and a second optical switch 252. The first optical switch 251 is located between the first beam splitter 211 and the second beam splitter 212 and is configured to be opened or closed under the control of an electrical signal. The second optical switch 252 is located between the third reflector 213c and the second beam splitter 212 and is configured to be opened or closed under the control of an electrical signal. Because the first sub-polarized light a1 and the third sub-polarized light b1 emitted by the first beam splitter 211 are transmitted to the second beam splitter 212 via different paths, the first optical switch 251 is located on the optical path for transmitting the first sub-polarized light a1. When the first optical switch 251 is turned on, the first sub-polarized light a1 can pass through the first optical switch 251 and the second beam splitter 212 and be emitted toward the first polarization controller 22. When the first optical switch 251 is turned off, the first sub-polarized light a1 cannot be emitted toward the first polarization controller 22. The second optical switch 252 is located on the optical path that transmits the third sub-polarized light b1. When the second optical switch 252 is on, the third sub-polarized light b1 can pass through the second optical switch 252 and the second beam splitter 212 and be emitted to the first polarization controller 22. When the second optical switch 252 is off, the third sub-polarized light b1 cannot be emitted to the first polarization controller 22. Furthermore, the second optical switch 252 can be located at other locations, for example, between the second reflector 213b and the third reflector 213c. Any location on the optical path that transmits only the third sub-polarized light b1 is acceptable, and this is not a limitation herein.

[0075] During the synchronization process of the first polarized light and the second polarized light, the first optical switch 251 can be controlled to open, and the second optical switch 252 can be controlled to close, so that the first polarization controller 22 receives only the first polarized light (i.e., the first sub-polarized light a1). At this time, the first polarization controller 22 is controlled by an electrical signal to adjust itself so that the optical power of the first polarized light detected by the first photodetector 24 meets the optical polarization state synchronization condition. Then, the first optical switch 251 is controlled to close, and the second optical switch 252 is controlled to open, so that the first polarization controller 22 receives only the second polarized light (i.e., the third sub-polarized light b1). At this time, the second polarization controller 23 is controlled by an electrical signal to adjust itself so that the optical power of the second polarized light b detected by the first photodetector 24 meets the optical polarization state synchronization condition, thereby achieving polarization state synchronization between the first polarized light and the second polarized light.

[0076] Optionally, in the embodiment of the present application, Figure 5 As shown, the first polarization controller 22 may be an electrically controlled polarizer, which can be used to rotate its own optical axis direction under the control of an electrical signal. During synchronization control of the first polarized light and the second polarized light, the first optical switch 251 is controlled to be open, and the second optical switch 252 is controlled to be closed, so that the first polarization controller 22 receives only the first polarized light. At this time, the electrically controlled polarizer is controlled by the electrical signal to rotate its own optical axis direction so that the optical power of the first polarized light detected by the first photodetector 24 meets the optical polarization state synchronization condition. For example, the optical polarization state synchronization condition may be that the light detected by the first photodetector 24 reaches a maximum value. At this time, the optical axis direction of the electrically controlled polarizer is consistent with the polarization direction of the first polarized light emitted by the electrically controlled polarizer, and the electrically controlled polarizer is controlled to stop rotating by the electrical signal so that the electrically controlled polarizer maintains the current optical axis direction. Then, the first optical switch 251 is controlled to be closed, and the second optical switch 252 is controlled to be opened, so that the first polarization controller 22 only receives the second polarized light. At this time, the second polarization controller 23 is controlled by an electrical signal to adjust itself so that the optical power of the second polarized light detected by the first photodetector 24 meets the optical polarization state synchronization condition, so that the polarization direction of the second polarized light is consistent with the optical axis direction of the electrically controlled polarizer, that is, the polarization direction of the second polarized light is consistent with the polarization direction of the first polarized light, thereby achieving polarization state synchronization between the first polarized light and the second polarized light.

[0077] In addition, the first polarization controller can also be other optical components. For example, the first polarization controller can include: an electrically controlled quarter wave plate, and an electrically controlled half wave plate located on the optical path of the electrically controlled quarter wave plate. The electrically controlled quarter wave plate can be used to rotate the direction of its own optical axis under the control of an electrical signal, and the electrically controlled half wave plate can be used to rotate the direction of its own optical axis under the control of an electrical signal. Figure 5In the specific setting, the electrically controlled quarter wave plate can be set between the electrically controlled half wave plate and the second beam splitter 212, or the electrically controlled half wave plate can be set between the electrically controlled quarter wave plate and the second beam splitter 212. The order of the electrically controlled quarter wave plate and the electrically controlled half wave plate is not limited here. In the process of controlling the first polarization controller to adjust itself, the electrically controlled quarter wave plate can be first controlled to rotate its own optical axis direction so that the optical power of the first polarized light detected by the first photodetector meets the optical polarization state synchronization condition. Then, the electrically controlled quarter wave plate is controlled to stop rotating its own optical axis direction, and the electrically controlled half wave plate is controlled to rotate its own optical axis direction so that the optical power of the first polarized light detected by the first photodetector meets the optical polarization state synchronization condition. Of course, the electrically controlled half wave plate can also be controlled to rotate its own optical axis direction first, and then the electrically controlled quarter wave plate can be controlled to rotate its own optical axis direction. This is not limited here.

[0078] Alternatively, the first polarization controller may include: a first electrically controlled quarter wave plate, a second electrically controlled quarter wave plate, and an electrically controlled half wave plate, wherein the electrically controlled half wave plate is located between the first electrically controlled quarter wave plate and the second electrically controlled quarter wave plate. The first electrically controlled quarter wave plate can be used to rotate the direction of its own optical axis under the control of an electrical signal, the second electrically controlled quarter wave plate can be used to rotate the direction of its own optical axis under the control of an electrical signal, and the electrically controlled half wave plate can be used to rotate the direction of its own optical axis under the control of an electrical signal. In the process of controlling the first polarization controller to adjust itself, the first electrically controlled quarter wave plate can be first controlled to rotate the direction of its own optical axis so that the optical power of the first polarized light detected by the first photodetector meets the optical polarization state synchronization condition. Then, the first electrically-controlled quarter-wave plate is controlled to stop rotating in the direction of its own optical axis, and the electrically-controlled half-wave plate is controlled to rotate in the direction of its own optical axis, so that the optical power of the first polarized light detected by the first photodetector meets the optical polarization state synchronization condition. After that, the electrically-controlled half-wave plate is controlled to stop rotating in the direction of its own optical axis, and the second electrically-controlled quarter-wave plate is controlled to rotate in the direction of its own optical axis, so that the optical power of the first polarized light detected by the first photodetector meets the optical polarization state synchronization condition.

[0079] Of course, in addition to the above three implementations of the first polarization controller, the first polarization controller may also adopt other optical components with polarization control functions, and the specific implementation of the first polarization controller is not limited here.

[0080] In one embodiment of the present application, the second polarization controller may include: an electrically controlled quarter wave plate, and an electrically controlled half wave plate located on the optical path of the electrically controlled quarter wave plate, wherein the electrically controlled quarter wave plate may be used to rotate the direction of its own optical axis under the control of an electrical signal, and the electrically controlled half wave plate may be used to rotate the direction of its own optical axis under the control of an electrical signal. By adjusting the optical axis direction of the electrically controlled quarter wave plate, elliptically polarized light or circularly polarized light may be converted into linearly polarized light, and by adjusting the optical axis direction of the electrically controlled half wave plate, the polarization direction of the linearly polarized light may be changed, thereby adjusting the polarization direction of the linearly polarized light to be consistent with the optical axis direction of the electrically controlled polarizer. Figure 5 In the specific setting, the electrically controlled quarter wave plate can be set between the electrically controlled half wave plate and the first beam splitter 211, or the electrically controlled half wave plate can be set between the electrically controlled quarter wave plate and the first beam splitter 211. The order of the electrically controlled quarter wave plate and the electrically controlled half wave plate is not limited here.

[0081] In the process of controlling the second polarization controller to adjust itself, the electrically controlled quarter-wave plate can be first controlled to rotate its own optical axis direction so that the optical power of the second polarized light detected by the first photodetector meets the optical polarization state synchronization condition. Then, the electrically controlled quarter-wave plate can be controlled to stop rotating its own optical axis direction, and the electrically controlled half-wave plate can be controlled to rotate its own optical axis direction so that the optical power of the second polarized light detected by the first photodetector meets the optical polarization state synchronization condition. Of course, it is also possible to first control the electrically controlled half-wave plate to rotate its own optical axis direction, and then control the electrically controlled quarter-wave plate to rotate its own optical axis direction, and this is not limited here.

[0082] In another embodiment of the present application, the above-mentioned second polarization controller may include: a first electrically controlled quarter wave plate, a second electrically controlled quarter wave plate, and an electrically controlled half wave plate, wherein the electrically controlled half wave plate is located between the first electrically controlled quarter wave plate and the second electrically controlled quarter wave plate. The first electrically controlled quarter wave plate can be used to rotate the direction of its own optical axis under the control of an electrical signal, the second electrically controlled quarter wave plate can be used to rotate the direction of its own optical axis under the control of an electrical signal, and the electrically controlled half wave plate can be used to rotate the direction of its own optical axis under the control of an electrical signal. By adjusting the optical axis direction of the first electrically controlled quarter wave plate (or the second electrically controlled quarter wave plate), elliptically polarized light or circularly polarized light can be converted into linearly polarized light, and by adjusting the optical axis direction of the electrically controlled half wave plate, the polarization direction of the linearly polarized light can be changed, so that the polarization direction of the linearly polarized light can be adjusted to be consistent with the optical axis direction of the electrically controlled polarizer. In addition, by providing two quarter wave plates and providing a half wave plate between the two quarter wave plates, the sensitivity of the second polarization controller can be improved.

[0083] Similarly, in the process of controlling the second polarization controller to adjust itself, the first electrically controlled quarter-wave plate can be first controlled to rotate its own optical axis direction so that the optical power of the second polarized light detected by the first photodetector meets the optical polarization state synchronization condition. Then, the first electrically controlled quarter-wave plate is controlled to stop rotating its own optical axis direction, and the electrically controlled half-wave plate is controlled to rotate its own optical axis direction so that the optical power of the second polarized light detected by the first photodetector meets the optical polarization state synchronization condition. Thereafter, the electrically controlled half-wave plate is controlled to stop rotating its own optical axis direction, and the second electrically controlled quarter-wave plate is controlled to rotate its own optical axis direction so that the optical power of the second polarized light detected by the first photodetector meets the optical polarization state synchronization condition.

[0084] In specific implementations, the specific structure of the second polarization controller in the embodiments of the present application may also be implemented using other methods. For example, the second polarization controller may also utilize an electrically controlled polarizer. During the process of controlling the second polarization controller to adjust itself, the electrically controlled polarizer may be controlled by an electrical signal to rotate its optical axis, so that the optical power of the second polarized light detected by the first photodetector satisfies the optical polarization state synchronization condition. Of course, the second polarization controller may also utilize other optical components with polarization control capabilities, and the specific structure of the second polarization controller is not limited herein.

[0085] Alternatively, as Figure 4 and Figure 5 As shown, the second polarization controller 23 can be disposed between the first beam splitter 211 and the fiber collimator 28. Thus, during synchronization between the first polarized light and the second polarized light, the second polarization controller 23 controls the polarization of the second polarized light b and then directs the second polarized light b toward the first beam splitter 211. This ensures that the polarization states of the third and fourth sub-polarized light b1 and b2, obtained by splitting the light by the first beam splitter 211, are synchronized with the polarization state of the first polarized light. Furthermore, this ensures that the fourth sub-polarized light operates in an optimal state when passing through the reflective liquid crystal on silicon 34 of the access point device 30.

[0086] exist Figure 5 In the illustrated spatial optical communication system, the beam deflection controller in the access point device 30 is a reflective liquid crystal on silicon 34, which is a linear polarization device. Therefore, in the optical path between the reflective liquid crystal on silicon 34 in the access point device 30 and the fiber collimator 28 in the terminal 20, the first polarized light and the second polarized light are both linearly polarized. It should be noted that the terminal in the embodiment of the present application can synchronize linearly polarized light. When the first polarized light and the second polarized light are other types of polarization, such as circular polarization or elliptically polarized light, the terminal can also synchronize the polarization states of the first polarized light and the second polarized light. The synchronization process is consistent with the process described above.

[0087] In practical applications, in order to control the various optical components in the optical polarization state synchronization device, the optical polarization state synchronization device in the embodiment of the present application may further include: a processor electrically connected to the first polarization controller, the second polarization controller, and the first photodetector. The processor may be a device with processing capabilities, such as a chip. The processor may be configured to control the first polarization controller to adjust itself via an electrical signal when the first polarization controller only receives the first polarized light, so that the optical power of the first polarized light detected by the first photodetector meets the optical polarization state synchronization condition; and to control the second polarization controller to adjust itself via an electrical signal when the first polarization controller only receives the second polarized light, so that the optical power of the second polarized light detected by the first photodetector meets the optical polarization state synchronization condition. In other words, the processor may control the first polarization controller and the second polarization controller via an electrical signal to polarize the first polarization light and the second polarization light, thereby achieving polarization state synchronization between the first polarization light and the second polarization light.

[0088] Based on the same technical concept, the embodiment of the present application also provides a terminal in a space optical communication system, such as Figure 5 As shown, the terminal 20 may include: any of the above-mentioned optical polarization state synchronization devices 200, an optical transceiver 27, and a fiber collimator 28 located on the optical path of the optical transceiver.

[0089] The optical transceiver 27 can be used to receive the second sub-polarized light a2 transmitted by the first beam splitter 211 in the optical polarization state synchronization device 200. The second sub-polarized light a2 is obtained by the first beam splitter 211 splitting the first polarized light a emitted by the access point device 30. In other words, a portion of the first polarized light emitted by the access point device 30 (i.e., the second sub-polarized light a2) is ultimately emitted to the optical transceiver 27 of the terminal 20, thereby enabling the access point device 30 to transmit optical communication information to the terminal 20.

[0090] The optical transceiver 27 can also be used to emit a second polarized light. The fiber collimator 28 can be used to collimate the second polarized light emitted by the optical transceiver 27 and transmit the collimated second polarized light b to the optical polarization state synchronization device 200. After the second polarized light b is split by the first beam splitter 211 in the optical polarization state synchronization device 200, the resulting fourth sub-polarized light b2 can be emitted to the access point device 30 after transmitting several meters in free space. After passing through the reflective silicon liquid crystal 34, polarization controller 33, and fiber collimator 32 in the access point device 30, it is emitted to the optical transceiver 31. In other words, a portion of the second polarized light emitted by the terminal 20 (i.e., the fourth sub-polarized light b2) is ultimately emitted to the optical transceiver 31 in the access point device 30, enabling the transmission of optical communication information from the terminal 20 to the access point device 30.

[0091] In an embodiment of the present application, by providing an optical polarization state synchronization device in the terminal, the first polarized light and the second polarized light can be synchronized on the terminal side. When performing polarization control on the first polarized light and the second polarized light, only one of the first polarized light and the second polarized light needs to be polarized to achieve polarization control of the first polarized light and the second polarized light, so that the first polarized light and the second polarized light can operate in an optimal state when passing through the beam deflection controller in the spatial optical communication system. Furthermore, the polarization control process can be simplified, the time delay of the polarization control process can be effectively reduced, and the response speed of information exchange can be improved.

[0092] In specific implementation, the processor in the optical polarization state synchronization device can be integrated into other processing components of the terminal, or the processor in the optical polarization state synchronization device can be set at other locations in the terminal. The setting location of the processor is not limited here.

[0093] In one embodiment of the present application, the terminal 20 may further include a two-dimensional rotating platform 29. The two-dimensional rotating platform 29 may be used to support optical components within the terminal 20, such as the optical path conversion assembly 21, the first polarization controller 22, the second polarization controller 23, the first photodetector 24, the optical transceiver 27, and the fiber collimator 28. The two-dimensional rotating platform 29 may be used to adjust the direction of the fourth sub-polarized light b2 transmitted by the first beam splitter 211, so that the second polarized light (i.e., the fourth sub-polarized light b2) ultimately emitted by the terminal 20 is directed toward the access point device 30, thereby enabling optical communication between the terminal 20 and the access point device 30. In a specific implementation, methods such as providing an optical sensor may be employed to capture, track, and align the first polarized light and the second polarized light, thereby improving optical communication between the terminal 20 and the access point device 30 and further enhancing the mobility of the terminal 20.

[0094] Figure 6 Another structural diagram of the spatial optical communication system provided in an embodiment of the present application is shown in FIG. Figure 6 As shown, in another embodiment of the present application, the terminal 20 may further include: a galvanometer 210 located on the optical path of the first beam splitter 211. The galvanometer 210 may be used to receive the fourth sub-polarized light b2 transmitted by the first beam splitter 211 and adjust itself under the control of an electrical signal. For example, the internal chip may be rotated under the control of the electrical signal to change the emission direction of the fourth sub-polarized light b2. That is, the function of the galvanometer 210 is similar to that of the two-dimensional rotating platform 29. The direction of the second polarized light (i.e., the fourth sub-polarized light b2) ultimately emitted by the terminal 20 may be adjusted so that the second polarized light emitted by the terminal 20 is directed toward the access point device 30, thereby achieving optical communication between the terminal 20 and the access point device 30.

[0095] Figure 7 Another structural diagram of the spatial optical communication system provided in an embodiment of the present application is shown in FIG. Figure 7 As shown, in another embodiment of the present application, the terminal 20 may further include a third beam splitter 401, a reflective liquid crystal on silicon (LCS) 402, a third polarization controller 403, and a second photodetector 404. The second polarized light emitted by the optical transceiver 27 passes through the fiber collimator 28 and the third polarization controller 403 before being emitted toward the reflective LCS 402. The reflective LCS 402 may be configured to receive the second polarized light emitted by the optical transceiver 27 and reflect the received second polarized light toward the third beam splitter 401. The third beam splitter 401 may be configured to receive the second polarized light and reflect a portion of the second polarized light toward the second photodetector 404, while transmitting another portion of the second polarized light toward the optical path conversion component 21 in the optical polarization state synchronization device. This portion of the second polarized light then passes through the optical path conversion component 21 and is emitted toward the access point device 30. The third polarization controller 403 is located on the light-entering side of the second photodetector 404. The third polarization controller 403 can be configured to adjust itself under the control of an electrical signal based on the optical power of the second polarized light detected by the second photodetector 404, so that the optical power of the second polarized light detected by the second photodetector 404 satisfies a set condition. For example, the set condition can be that the optical power of the second polarized light detected by the second photodetector 404 reaches a maximum value. Optionally, a second lens 405 can be disposed between the third beam splitter 401 and the second photodetector 404. The second lens 405 can converge the second polarized light reflected by the third beam splitter 401, thereby ensuring a more accurate optical power reading of the light detected by the second photodetector 404.

[0096] exist Figure 7 In the embodiment shown, by providing a third beam splitter 401, the second polarized light can be split into two beams of light, one of which continues to be transmitted to the access point device 30, and the other beam of light can be used for the polarization control process of the second polarized light. By providing a third polarization controller 403 and a second photodetector 404, the second polarized light can be polarized at the terminal 20 side, that is, the number of polarization controls of the second polarized light is increased, and the polarization control accuracy of the first polarized light and the second polarized light in the optical communication system is improved, so that the first polarized light and the second polarized light can operate in the optimal state at the beam deflection controller. Of course, since the terminal 20 can perform polarization control on the second polarized light, and the first polarized light and the second polarized light can achieve polarization state synchronization in the terminal 20, the optical components for polarization control of the first polarized light in the access point device 30 can be omitted, for example, the optical components for polarization control of the first polarized light can be omitted. Figure 7 The access point device 30 includes optical components such as the polarization controller 33, the beam splitter 37 and the photodetector 35.

[0097] Furthermore, reflective silicon-based liquid crystal 402 can reflect the second polarized light and deflect the incident second polarized light at any angle. During operation, the reflective silicon-based liquid crystal 402 can control the deflection of the liquid crystal molecules to adjust the reflection angle of the second polarized light within a range of 0 to 90 degrees. Thus, by adjusting the reflection angle of the second polarized light by reflective silicon-based liquid crystal 402, the second polarized light emitted by terminal 20 can be directed toward the corresponding access point device 30, thereby enabling optical communication between terminal 20 and access point device 30.

[0098] In an embodiment of the present application, the structure of the third polarization controller may be similar to the structure of the above-mentioned second deflection controller, that is, the third polarization controller may include: an electrically controlled quarter wave plate, and an electrically controlled half wave plate located on the optical path of the electrically controlled quarter wave plate; or, the third polarization controller may include: a first electrically controlled quarter wave plate, a second electrically controlled quarter wave plate, and an electrically controlled half wave plate, and the electrically controlled half wave plate is located between the first electrically controlled quarter wave plate and the second electrically controlled quarter wave plate. Of course, the third polarization controller may also be implemented in other ways, which is not limited here.

[0099] Figure 8 Another structural diagram of the spatial optical communication system provided in an embodiment of the present application is shown in FIG. Figure 8 As shown, in another embodiment of the present application, the terminal 20 may further include: a fourth beam splitter 406, a liquid crystal polarization grating 407, a fourth polarization controller 408, and a third photodetector 409. The liquid crystal polarization grating 407 may be used to receive the second polarized light emitted by the optical transceiver 27 and transmit the received second polarized light to the fourth beam splitter 406. The fourth beam splitter 406 may be used to receive the second polarized light and reflect a portion of the second polarized light to the third photodetector 409, while transmitting another portion of the second polarized light to the optical path conversion component 21 in the optical polarization state synchronization device 200. The fourth polarization controller 408 is located on the light incident side of the third photodetector 409. The fourth polarization controller 408 is used to adjust itself under the control of an electrical signal based on the optical power of the second polarized light detected by the third photodetector 409, so that the optical power of the second polarized light detected by the third photodetector 409 meets a set condition.

[0100] Compared to Figure 7 The terminal shown in Figure 8 The fourth beam splitter 406 and the Figure 7 The third beam splitter 401 in FIG. 4 has the same function as the fourth polarization controller 408. Figure 7 The third polarization controller 403 has the same function as the third photodetector 409, and the third photodetector 409 has the same function as the second photodetector 404. In addition, Figure 8The terminal 20 shown may further include: a third lens 410 located between the fourth beam splitter 406 and the third photodetector 109, the third lens 410 and the Figure 7 The second lens 405 has the same function as Figure 8 Zhongyu Figure 7 Devices with the same function will not be described in detail here. Figure 8 The terminal is replaced by liquid crystal polarization grating 407 Figure 7 The reflective silicon-based liquid crystal 402 is disposed in the liquid crystal polarization grating 407. The liquid crystal polarization grating 407 transmits the second polarized light and can also deflect the incident second polarized light at any angle. When the liquid crystal polarization grating 407 is in operation, the output angle of the second polarized light can be adjusted within a range of 0 to 90 degrees by controlling the deflection of the liquid crystal molecules. Thus, by adjusting the output angle of the second polarized light through the liquid crystal polarization grating 407, the second polarized light emitted by the terminal 20 is directed toward the corresponding access point device 30, thereby enabling optical communication between the terminal 20 and the access point device 30.

[0101] Based on the same technical concept, an embodiment of the present application also provides an access point device in a spatial optical communication system. Figure 9 Another structural diagram of the spatial optical communication system provided in an embodiment of the present application is shown in FIG. Figure 9 As shown, the access point device 30 may include: any of the above-mentioned optical polarization state synchronization devices 200. That is, the above-mentioned optical polarization state synchronization device 200 may also be provided in the access point device 30 of the spatial optical communication system.

[0102] In a spatial optical communication system, the optical polarization state synchronization device 200 may be provided only in the access point device 30. Furthermore, the number of optical polarization synchronization devices 200 in the access point device 30 may be consistent with the number of terminals 20 corresponding to the access point device 30, thereby achieving polarization state synchronization of multiple groups of first polarized light and second polarized light.

[0103] Specifically, continue to refer to Figure 9 The optical polarization state synchronization device 200 in the access point device 30 may include: an optical path conversion component 21, a first polarization controller 22 located on the light-outgoing side of the optical path conversion component 21, a second polarization controller 23 located on the light-incoming side of the optical path conversion component 21, a first photodetector 24 located on the light-outgoing side of the first polarization controller 22, an optical path selection component 25 located on the light-incoming side of the first polarization controller 22, and a first lens 26. The principle of controlling the polarization state synchronization between the first polarized light and the second polarized light on the access point device 30 side is similar to the principle of controlling the polarization state synchronization between the first polarized light and the second polarized light on the terminal 20 side. Furthermore, the functions and structures of the optical components of the optical polarization state synchronization device in the access point device 30 are similar to those of the corresponding optical components in the terminal 20, and are not further described herein.

[0104] Of course, if Figure 8 As shown, the optical polarization state synchronization device 200 can be provided in both the terminal 20 and the access point device 30, thereby further improving the synchronization effect of the polarization states of the first polarized light and the second polarized light in the spatial optical communication system.

[0105] In specific implementation, the processor in the optical polarization state synchronization device can be integrated into other processing components of the access point device, or the processor in the optical polarization state synchronization device can be set at other locations in the access point device. The setting location of the processor is not limited here.

[0106] Based on the same technical concept, the embodiment of the present application also provides a space optical communication system, which may include: a terminal, and an access point device. By sending a first polarized light to the terminal through the access point device, and the terminal sending a second polarized light to the access point device, information interaction between the access point device and the terminal can be achieved. In a specific implementation, the terminal may include any of the above-mentioned optical polarization state synchronization devices; and / or, the access point device may include any of the above-mentioned optical polarization state synchronization devices. Among them, the above-mentioned terminal may be Figures 5 to 9 Any terminal shown in .

[0107] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. An optical polarization state synchronization device, characterized in that: include: An optical path conversion component, a first polarization controller located on the light-outgoing side of the optical path conversion component, a second polarization controller located on the light-incoming side of the optical path conversion component, and a first photodetector located on the light-outgoing side of the first polarization controller; The optical path conversion component is configured to receive a first polarized light and a second polarized light, and transmit the received first polarized light and the second polarized light to the first polarization controller; The first polarization controller is configured to adjust itself under the control of an electrical signal when receiving only the first polarized light, so that the optical power of the first polarized light detected by the first photodetector satisfies an optical polarization state synchronization condition; the second polarization controller is configured to adjust itself under the control of an electrical signal when the first polarization controller receives only the second polarized light, so that the optical power of the second polarized light detected by the first photodetector satisfies the optical polarization state synchronization condition; The optical polarization state synchronization device further includes: an optical path selection component located on the light incident side of the first polarization controller; The optical path selection component is used to block the second polarized light and transmit the first polarized light so that the first polarization controller only receives the first polarized light; or to block the first polarized light and transmit the second polarized light so that the first polarization controller only receives the second polarized light.

2. The optical polarization state synchronization device according to claim 1, wherein: The optical path conversion component includes: a first beam splitter, a second beam splitter located between the first beam splitter and the first polarization controller, and a reflection component; The first beam splitter is configured to receive the first polarized light, split the received first polarized light into a first sub-polarized light and a second sub-polarized light, reflect the first sub-polarized light to the second beam splitter, and transmit the second sub-polarized light; The second beam splitter is configured to transmit the received first sub-polarized light to the first polarization controller; The first beam splitter is further configured to receive the second polarized light, split the received second polarized light into a third sub-polarized light and a fourth sub-polarized light, reflect the third sub-polarized light to the reflective component, and transmit the fourth sub-polarized light; The reflecting component is configured to reflect the received third sub-polarized light to the second beam splitter; The second beam splitter is further configured to reflect the received third sub-polarized light to the first polarization controller.

3. The optical polarization state synchronization device according to claim 2, wherein: The reflective assembly includes: a first reflector located on the optical path of the first beam splitter, a second reflector located on the optical path of the first reflector, and a third reflector located on the optical path of the second reflector; The first reflector is located on a side of the first beam splitter away from the first polarization controller in a first direction, and is configured to receive the third sub-polarized light reflected by the first beam splitter and reflect the received third sub-polarized light to the second reflector; the first direction is a direction in which the first polarization controller points toward the first beam splitter; The second reflector is located on one side of the first reflector in the second direction, and is used to reflect the received third sub-polarized light to the third reflector; the second direction is a direction perpendicular to the first direction; The second reflector and the third reflector are located on both sides of the first beam splitter in the first direction, and the second reflector and the third reflector are located on the same side of the first beam splitter in the second direction; The third reflector is configured to reflect the received third sub-polarized light to the second beam splitter.

4. The optical polarization state synchronization device according to claim 3, wherein: The optical path selection component includes: a first optical switch and a second optical switch; The first optical switch is located between the first beam splitter and the second beam splitter; The second optical switch is located between the third reflector and the second beam splitter.

5. The optical polarization state synchronization device according to any one of claims 1 to 4, characterized in that: The polarization controller is an electrically controlled polarizer; The electrically controlled polarizer is used to rotate the direction of its own optical axis under the control of an electrical signal; Alternatively, the polarization controller includes: an electrically controlled quarter wave plate, and an electrically controlled half wave plate located in the optical path of the electrically controlled quarter wave plate; the electrically controlled quarter wave plate is used to rotate the direction of its own optical axis under the control of an electrical signal; the electrically controlled half wave plate is used to rotate the direction of its own optical axis under the control of an electrical signal; Alternatively, the polarization controller includes: a first electrically controlled quarter wave plate, a second electrically controlled quarter wave plate, and an electrically controlled half wave plate; the electrically controlled half wave plate is located between the first electrically controlled quarter wave plate and the second electrically controlled quarter wave plate; the first electrically controlled quarter wave plate is used to rotate the direction of its own optical axis under the control of an electrical signal; the second electrically controlled quarter wave plate is used to rotate the direction of its own optical axis under the control of an electrical signal; the electrically controlled half wave plate is used to rotate the direction of its own optical axis under the control of an electrical signal; Wherein, the polarization controller is the first polarization controller or the second polarization controller.

6. The optical polarization state synchronization device according to any one of claims 1 to 4, characterized in that: Also includes: A first lens is positioned between the first polarization controller and the first photodetector.

7. The optical polarization state synchronization device according to any one of claims 1 to 4, characterized in that: Also included: a processor electrically connected to the first polarization controller, the second polarization controller, and the first photodetector; The processor is used to control the first polarization controller to adjust itself through an electrical signal when the first polarization controller only receives the first polarized light, so that the optical power of the first polarized light detected by the first photodetector meets the optical polarization state synchronization condition; when the first polarization controller only receives the second polarized light, the processor is used to control the second polarization controller to adjust itself through an electrical signal so that the optical power of the second polarized light detected by the first photodetector meets the optical polarization state synchronization condition.

8. A terminal in a space optical communication system, characterized in that: include: The optical polarization state synchronization device according to any one of claims 1 to 7, an optical transceiver, and a fiber collimator located on the optical path of the optical transceiver; The optical transceiver is used to receive the first polarized light transmitted by the optical polarization state synchronization device or emit the second polarized light; The optical fiber collimator is used to collimate the second polarized light emitted by the optical transceiver and transmit the collimated second polarized light to the optical polarization state synchronization device.

9. The terminal according to claim 8, wherein: The optical path conversion component in the optical polarization state synchronization device includes: a first beam splitter, the first beam splitter is used to receive the second polarized light and split the received second polarized light into a third sub-polarized light and a fourth sub-polarized light; The terminal further includes: a two-dimensional rotating platform; The two-dimensional rotating platform is used to carry the optical components in the terminal and to adjust the direction of the fourth sub-polarized light transmitted by the first beam splitter.

10. The terminal according to claim 8, wherein The optical path conversion component in the optical polarization state synchronization device includes: a first beam splitter, the first beam splitter is used to receive the second polarized light and split the received second polarized light into a third sub-polarized light and a fourth sub-polarized light; The terminal further includes: a galvanometer located on the optical path of the first beam splitter; The galvanometer is used to receive the fourth sub-polarized light transmitted by the first beam splitter and adjust itself under the control of the electrical signal to change the emission direction of the fourth sub-polarized light.

11. The terminal according to claim 8, wherein Also includes: a third beam splitter, a reflective liquid crystal on silicon, a third polarization controller, and a second photodetector; The reflective silicon-based liquid crystal is used to receive the second polarized light emitted by the optical transceiver and reflect the received second polarized light to the third beam splitter; The third beam splitter is configured to receive the second polarized light and reflect a portion of the second polarized light to the second photodetector, while transmitting another portion of the second polarized light to the optical path conversion component in the optical polarization state synchronization device; The third polarization controller is located on the light incident side of the second photodetector, and is used to adjust itself under the control of an electrical signal according to the optical power of the second polarized light detected by the second photodetector, so that the optical power of the second polarized light detected by the second photodetector meets the set conditions.

12. The terminal according to claim 8, wherein Also includes: a fourth beam splitter, a liquid crystal polarization grating, a fourth polarization controller, and a third photodetector; The liquid crystal polarization grating is used to receive the second polarized light emitted by the optical transceiver and transmit the received second polarized light to the fourth beam splitter; The fourth beam splitter is configured to receive the second polarized light and reflect a portion of the second polarized light to the third photodetector, while transmitting another portion of the second polarized light to the optical path conversion component in the optical polarization state synchronization device; The fourth polarization controller is located on the light incident side of the third photodetector, and is used to adjust itself under the control of an electrical signal according to the optical power of the second polarized light detected by the third photodetector, so that the optical power of the second polarized light detected by the third photodetector meets the set conditions.

13. An access point device in a space optical communication system, characterized in that: The device comprises the optical polarization state synchronization device as claimed in any one of claims 1 to 7.

14. A space optical communication system, characterized in that: include: Terminal and access point devices; The terminal includes the optical polarization state synchronization device according to any one of claims 1 to 7; and / or the access point device includes the optical polarization state synchronization device according to any one of claims 1 to 7.

15. The spatial optical communication system according to claim 14, wherein: The terminal is the terminal according to any one of claims 8 to 12.

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