Satellite-borne laser communication system based on flat synthetic aperture and working method thereof

Abstract

The invention relates to a satellite-borne laser communication system based on a flat synthetic aperture and a working method of the satellite-borne laser communication system. A micro lens group of the satellite-borne laser communication system comprises a plurality of micro lenses arranged in an array. The emission light path group comprises a laser emitter, a beam splitter and a plurality of phase modulators. And the signal processor is used for encoding data needing to be sent, modulating the encoded data onto the laser beam, and emitting the laser beam through the laser emitter. The beam splitter is located on a light path of the laser beam and used for splitting the laser beam to form a plurality of sub-beams, and each sub-beam is transmitted to the corresponding micro-lens after passing through the phase modulator. The plurality of micro lenses are divided into a plurality of areas, each area comprises at least two micro lenses, and sub light beams emitted from the at least two micro lenses of each area are coherently combined to form a combined light beam pointing to a set direction. The directions of the combined light beams in different areas in the multiple areas are different. Therefore, the transmission rate and the transmission distance of the laser communication signal can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser communication, and particularly relates to a spaceborne laser communication system based on a flat synthetic aperture and its working method. Background Art

[0002] With the rapid development of space technology, satellite communication has become an important part of modern information society. Traditional microwave communication is limited by bandwidth and frequency resources and is difficult to meet the growing demand for high-speed data transmission. Laser communication, with its advantages of large bandwidth, high transmission rate, strong anti-interference ability, etc., has become an important development direction for future satellite communication. However, laser communication also faces technical challenges such as beam divergence, atmospheric interference, and large alignment difficulty. Especially when performing long-distance laser communication between satellites or between a satellite and a ground station, how to ensure the transmission rate and transmission distance of laser communication is a difficult point in the current technical field. Summary of the Invention

[0003] In view of this, the present invention aims to provide a spaceborne laser communication system based on a flat synthetic aperture and its working method, which can improve the transmission rate and transmission distance of laser communication signals.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows:

[0005] A spaceborne laser communication system based on a flat synthetic aperture includes a flat structure, a signal processor, a microlens array, and a transmitting optical path group:

[0006] The microlens array is arranged on the flat structure, and the microlens array includes a plurality of microlenses arranged in an array;

[0007] The transmitting optical path group includes a laser transmitter, a beam splitter, and a plurality of phase modulators; the phase modulators are correspondingly arranged with the microlenses; the signal processor is used to encode the data to be transmitted and modulate the encoded data onto the laser beam, and the laser beam is emitted through the laser transmitter; the beam splitter is located on the optical path of the laser beam and is used to split the laser beam to form multiple sub-beams, and each sub-beam is transmitted to the corresponding microlens after passing through the phase modulator;

[0008] The plurality of microlenses are divided into a plurality of regions, each region includes at least two microlenses, and the sub-beams emitted from at least two microlenses in each region are coherently combined to form a combined beam pointing in a set direction; the pointing directions of the combined beams in different regions among the plurality of regions are different.

[0009] Further, the phase modulator is used to adjust the phase difference between the sub-beams emitted from two adjacent microlenses in each region and adjust the phase difference to a set value so that the sub-beams emitted from at least two microlenses in each region are coherently combined.

[0010] Further, it also includes a photodetector and multiple receiving optical path groups;

[0011] The receiving optical path groups are arranged corresponding to the microlenses. The incident laser beam is split into multiple sub-beams by the microlens group. After each sub-beam passes through the corresponding receiving optical path group, it is incident on the photodetector. The photodetector converts the laser signals of the multiple sub-beams into electrical signals and transmits the electrical signals to the signal processor, and the signal processor processes the electrical signals.

[0012] Further, the receiving optical path group includes a diaphragm. After each sub-beam passes through the diaphragm, it is incident on the photodetector.

[0013] Further, the receiving optical path group includes a filter. After each sub-beam passes through the filter, it is incident on the photodetector.

[0014] Further, the receiving optical path group includes a focusing lens. Each sub-beam passes through the focusing lens and is focused on the photodetector.

[0015] Further, it also includes a fine-tuning mechanism. The fine-tuning mechanism includes a controller and an adjustment component. The adjustment component is connected to the flat structure. The controller is used to rotate the flat structure through the adjustment component according to the intensity of the optical signal incident on the photodetector to increase the intensity of the optical signal received by the photodetector.

[0016] A working method of a spaceborne laser communication system based on a flat synthetic aperture is applied to a spaceborne laser communication system based on a flat synthetic aperture. The spaceborne laser communication system includes a signal processor, a microlens group, and a transmitting optical path group. The microlens group includes multiple microlenses arranged in an array. The transmitting optical path group includes a laser transmitter, a beam splitter, and multiple phase modulators. The phase modulators and the microlenses are arranged corresponding to each other. The working method includes:

[0017] Encoding the data to be transmitted by the signal processor, modulating the encoded data onto the laser beam, and emitting the laser beam through the laser transmitter;

[0018] Splitting the laser beam emitted by the laser transmitter through the beam splitter, splitting the laser beam into multiple sub-beams. After each sub-beam passes through the phase modulator, it is transmitted to the corresponding microlens;

[0019] The multiple microlenses of the microlens group are divided into multiple regions. Each region includes at least two microlenses. The sub-beams emitted from at least two microlenses in each region are coherently synthesized to form a synthesized beam pointing in a set direction. The pointing directions of the synthesized beams in different regions among the multiple regions are different.

[0020] Further, by adjusting the phase modulators corresponding to at least two microlenses in each region, the phase difference between the sub-beams emitted from two adjacent microlenses in each region is set to a set value, so that the sub-beams emitted from at least two microlenses in each region are coherently combined.

[0021] Further, the spaceborne laser communication system further includes a photodetector and a plurality of receiving optical path groups, and the receiving optical path groups are arranged corresponding to the microlenses; the working method includes:

[0022] The incident laser beam is split into multiple sub-beams by the microlens group, and after passing through the corresponding receiving optical path group, it is incident on the photodetector;

[0023] The laser signals of the multiple sub-beams are converted into electrical signals by the photodetector, and the electrical signals are transmitted to the signal processor;

[0024] The electrical signals output by the photodetector are processed by the signal processor.

[0025] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0026] A spaceborne laser communication system based on a flat synthetic aperture provided by the present invention, on the one hand, the spaceborne laser communication system can realize the emission of laser beams. At the same time, multiple synthetic beams pointing in different directions can be formed simultaneously, so that multiple laser communication signals can be transmitted simultaneously, expanding the communication bandwidth and improving the transmission rate of laser communication signals. At the same time, the sub-beams emitted from at least two microlenses in each region are coherently combined, which can ensure that the emitted beam has a high concentration, improve the pointing accuracy and resolution of the emitted beam, and thus improve the transmission distance of laser communication signals. Enabling the improvement of the transmission rate and communication distance, high-speed and long-distance laser communication can be achieved. On the other hand, the spaceborne laser communication system can realize the reception of laser beams, so that the multiple microlenses of the microlens group can be equivalent to a virtual large aperture, effectively solving problems such as beam divergence, atmospheric interference and large alignment difficulty in laser communication, and improving the stability of the communication link. Thus, it can provide strong technical support for satellite communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0028] Figure 1 It is a three-dimensional schematic diagram when the spaceborne laser communication system described in the embodiment of the present invention is applied to a satellite;

[0029] Figure 2Schematic three-dimensional diagram of the spaceborne laser communication system described in the embodiments of the present invention;

[0030] Figure 3 Structural diagram of the spaceborne laser communication system described in the embodiments of the present invention;

[0031] Figure 4 Flowchart of emitting a laser beam in the working method of the spaceborne laser communication system described in the embodiments of the present invention;

[0032] Figure 5 Flowchart of receiving a laser beam in the working method of the spaceborne laser communication system described in the embodiments of the present invention.

[0033] Explanation of reference numerals:

[0034] 10. Spaceborne laser communication system; 11. Flat structure; 12. Signal processor; 13. Microlens group; 14. Transmitting optical path group; 15. Microlens; 16. Laser transmitter; 17. Beam splitter; 18. Phase modulator; 19. Photoelectric detector; 20. Receiving optical path group; 21. Diaphragm; 22. Filter; 23. Focusing lens. Detailed implementation manners

[0035] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention. Similar elements in different embodiments are labeled with related similar element numbers. In the following embodiments, many detailed descriptions are provided to enable a better understanding of the present invention. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, or methods. In some cases, some operations related to the present invention are not shown or described in the specification to avoid the core part of the present invention being overwhelmed by excessive descriptions. For those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations based on the descriptions in the specification and general technical knowledge in the art.

[0036] It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other to form various implementation manners. At the same time, the steps or actions in the method description can also be reordered or adjusted in an obvious manner by those skilled in the art. Therefore, the various sequences in the specification and drawings are only for clearly describing a certain embodiment and do not mean that they are the necessary sequences, unless it is stated that a certain sequence must be followed.

[0037] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation on the present invention. In addition, terms such as "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0038] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0039] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0040] See Figure 1 、 Figure 2 and Figure 3 As shown, the embodiment of the present invention provides a spaceborne laser communication system 10 based on a flat synthetic aperture type. The spaceborne laser communication system 10 can be arranged on a satellite or on a ground station, and can realize laser communication between satellites and between a satellite and a ground station. In Figure 1 In the shown embodiment, the spaceborne laser communication system 10 is arranged on a satellite. The spaceborne laser communication system 10 includes a flat plate structure 11, a signal processor 12, a microlens group 13, and a transmitting optical path group 14.

[0041] The microlens group 13 is arranged on the flat plate structure 11. By adopting the flat plate structure 11, the weight, volume, and manufacturing cost of the spaceborne laser communication system 10 can be greatly reduced, which is convenient for deployment and carrying. The microlens group 13 includes a plurality of microlenses 15 arranged in an array. The plurality of microlenses 15 can be arranged in a rectangular array, a hexagonal array, a circular array, etc. In Figure 2In the illustrated embodiment, the microlens array 13 includes multiple rows and columns of microlenses 15, and the multiple rows and columns of microlenses 15 are arranged at uniform intervals along the circumferential direction of the flat structure 11. One row of microlenses 15 columns includes a plurality of microlenses 15 arranged in a straight line. The arrangement of such a plurality of microlenses 15 is more compact, making full use of the space of the flat structure 11 and improving the effect of synthetic aperture.

[0042] The transmitting optical path group 14 includes a laser transmitter 16, a beam splitter 17, and a plurality of phase modulators 18. The laser transmitter 16 is used to emit a laser beam, and the laser transmitter 16 can have characteristics such as high power, narrow linewidth, and stable output to ensure the long-distance transmission and precise alignment of the laser beam. Among them, the beam splitter 17 and the plurality of phase modulators 18 can be integrated on a photonic integrated chip using photonics integration technology. The output end of the laser transmitter 16 is connected to the input end of the photonic integrated chip through an optical fiber, and the output end of the photonic integrated chip is connected to the microlens array 13 through an optical fiber array. The phase modulators 18 and the microlenses 15 are arranged in correspondence, and one phase modulator 18 can be arranged corresponding to one microlens 15. The signal processor 12 is used to encode the data to be transmitted and modulate the encoded data onto the laser beam, and the laser beam is emitted through the laser transmitter 16. The signal processor 12 includes an encoder, and the encoder is used to encode the data to be transmitted, and then the encoded data is modulated onto the laser beam through the signal processor 12. The beam splitter 17 can be an MMI (Multi-Mode Interference) beam splitter 17. The beam splitter 17 is located on the optical path of the laser beam and is used to split the laser beam to form multiple sub-beams. After each sub-beam passes through the phase modulator 18, it is transmitted to the corresponding microlens 15. The multiple sub-beams formed by the laser beam can be distributed to the corresponding phase modulators 18 and transmitted to the corresponding microlenses 15 to be emitted to a target or other communication nodes. In this way, the phase of each sub-beam can be controlled by the phase modulator 18, so that the coherent enhancement of multiple sub-beams can be achieved.

[0043] A plurality of microlenses 15 are divided into a plurality of regions, each region including at least two microlenses 15. Sub-beams emitted from at least two microlenses 15 in each region are coherently combined to form a combined beam directed in a set direction. The directions of the combined beams in different regions among the plurality of regions are different. Dividing the plurality of microlenses 15 into a plurality of regions, each region can form a combined beam directed in a set direction. Thus, at the same moment, multiple combined beams directed in different directions can be formed simultaneously, enabling multiple laser communication signals to be transmitted simultaneously, expanding the communication bandwidth and increasing the transmission rate of the laser communication signals. At the same time, the sub-beams emitted from at least two microlenses 15 in each region are coherently combined, which can ensure that the emitted beam has a high concentration, improving the pointing accuracy and resolution of the emitted beam, thereby increasing the transmission distance of the laser communication signals.

[0044] In one embodiment, the phase modulator 18 is used to adjust the phase difference between the sub-beams emitted from two adjacent microlenses 15 in each region to a set value, so that the sub-beams emitted from at least two microlenses 15 in each region are coherently combined. The phase of the sub-beam emitted from the corresponding microlens 15 can be adjusted by the phase modulator 18, so that the phase difference between the sub-beams emitted from two adjacent microlenses 15 in each region is a set value, so that the sub-beams emitted from at least two microlenses 15 in each region are coherently combined to form a combined beam directed in a set direction. The set values in different regions among the plurality of regions are different, so that combined beams with different directions can be formed.

[0045] In one embodiment, the spaceborne laser communication system 10 further includes a photodetector 19 and a plurality of receiving optical path groups 20. The receiving optical path groups 20 are arranged corresponding to the microlenses 15, and one receiving optical path group 20 can be arranged corresponding to one microlens 15. The incident laser beam is split into multiple sub-beams by the microlens group 13. After each sub-beam passes through the corresponding receiving optical path group 20, it is incident on the photodetector 19. In this way, the microlens group 13 can split the laser beam incident on a large area into multiple sub-beams, and each microlens 15 will focus the incident laser beam on the corresponding focal plane, so that multiple focal points can be formed on the focal plane of the microlens group 13. The focal points can be received by the photodetector 19 through the receiving optical path group and converted into electrical signals. Among them, the photodetector 19 can adopt components such as CCD (Charge-Coupled Device), CMOS (Complementary Metal-Oxide-Semiconductor), APD (Avalanche Photodiode), and SPAD (Single-Photon Avalanche Diode). The outgoing sub-beams of the multiple microlenses 15 can form a stable interference pattern at the target position. The interference pattern not only improves the resolution of the laser beam but also can be used as a reference signal for alignment, thereby reducing the difficulty of alignment. The photodetector 19 converts the laser signals of the multiple sub-beams into electrical signals and transmits the electrical signals to the signal processor 12, and the signal processor 12 processes the electrical signals. The signal processor 12 can recover the original data. The original data output from the signal processor 12 can be processed and / or stored. Thus, the spaceborne laser communication system 10 has the advantages of high-sensitivity laser beam receiving ability, large dynamic range, low noise, and fast response. Among them, each microlens 15 can be equivalent to a sub-aperture, so that the multiple microlenses 15 of the microlens group 13 can be equivalent to a virtual large aperture, and high-precision laser signal reception can be achieved through electrical signal synthesis.

[0046] In one embodiment, the signal processor 12 further includes a preamplifier, an analog-to-digital converter, a digital signal processor 12, and a decoder arranged in sequence. The preamplifier is used to amplify the received electrical signal to improve the signal quality of the electrical signal. The analog-to-digital converter is used to convert the electrical signal received from the preamplifier into a digital signal. The digital signal processor 12 is used to analyze and process the received digital signal. The decoder is used to decode the processed digital signal to recover the original data.

[0047] In one embodiment, the receiving optical path group 20 includes a diaphragm 21. After each sub-beam of light passes through the diaphragm 21, it is incident on the photodetector 19. The diaphragm 21 can adjust its light passing aperture according to actual requirements to limit stray light from entering the subsequent optical path and improve the signal-to-noise ratio.

[0048] In one embodiment, the receiving optical path group 20 includes a filter 22. After each sub-beam of light passes through the filter 22, it is incident on the photodetector 19. The filter 22 is used to filter out light of non-target wavelengths.

[0049] In one embodiment, the receiving optical path group 20 includes a focusing lens 23. Each sub-beam of light passes through the focusing lens 23 and is focused on the photodetector 19. The photodetector 19 is disposed on the focal plane of the focusing lens 23. The focusing lens 23 is used to focus the sub-beams of each microlens 15 on the photodetector 19. The focusing lens 23 can adopt an achromatic lens or an aspherical lens to reduce aberration.

[0050] In this embodiment, the incident laser beam is split into multiple sub-beams by the microlens group 13. Each sub-beam of light sequentially passes through the diaphragm 21, the filter 22, and is focused on the photodetector 19 by the focusing lens 23. The receiving optical path group 20 can guide, focus, and shape the laser beam, reducing the loss of the laser signal and the interference of the stray light signal, and ensuring the accurate transmission and reception of the laser signal.

[0051] In one embodiment, the spaceborne laser communication system 10 further includes a fine-tuning mechanism. The fine-tuning mechanism includes a controller and an adjustment component. The adjustment component is connected to the flat structure 11. The adjustment component includes a driving member and a transmission component. The driving member is connected to the transmission component. The driving member can adopt a stepper motor or a servo motor. The transmission component can adopt structures such as a gear-rack component or a lead screw-nut component. The driving member is connected to the flat structure 11 through the transmission component. The driving member can drive the flat structure 11 to rotate through the transmission component to achieve precise adjustment of the position and angle of the flat structure 11 and the microlens group 13 thereon. The controller is used to rotate the flat structure 11 through the adjustment component according to the intensity of the optical signal incident on the photodetector 19 to increase the intensity of the optical signal received by the photodetector 19. In this way, the accurate alignment of the incident laser beam can be ensured.

[0052] In one embodiment, the fine-tuning mechanism further includes an angle sensor. The angle sensor can adopt a high-precision encoder or an inclination sensor. The angle sensor can collect the angle information of the flat structure 11 in real time. The controller can receive the angle information of the flat structure 11 collected by the angle sensor and rotate the flat structure 11 through the adjustment component, so as to achieve precise adjustment of the angle of the flat structure 11 and realize closed-loop control.

[0053] In one embodiment, the spaceborne laser communication system 10 further includes a computer unit, which includes a computer controller. The computer controller is used to execute a synthetic aperture algorithm, and the synthetic aperture algorithm can adopt a deep learning algorithm, such as a Convolutional Neural Network (CNN), to process the original data signals converted from the laser signals received by the sub-beams of each microlens 15. The deep learning algorithm may specifically include: preprocessing the original data signals. Inputting the data signals into a deep learning model for image reconstruction, and outputting a high-resolution image to a display. Thus, by executing the synthetic aperture algorithm, the stability of the laser communication link and the transmission efficiency of laser communication can be improved.

[0054] A spaceborne laser communication system 10 based on a flat-plate synthetic aperture provided by the present invention, on the one hand, the spaceborne laser communication system 10 can realize the emission of laser beams. At the same moment, multiple synthetic beams pointing in different directions can be formed simultaneously, so that multiple laser communication signals can be transmitted simultaneously, expanding the communication bandwidth and increasing the transmission rate of laser communication signals. At the same time, the sub-beams emitted from at least two microlenses 15 in each area are coherently combined, which can ensure that the emitted beam has a high concentration, improving the pointing accuracy and resolution of the emitted beam, thereby increasing the transmission distance of laser communication signals. The increase in transmission rate and communication distance enables high-speed and long-distance laser communication. On the other hand, the spaceborne laser communication system 10 can realize the reception of laser beams, making the multiple microlenses 15 of the microlens group 13 equivalent to a virtual large aperture, effectively solving problems such as beam divergence, atmospheric interference, and large alignment difficulty in laser communication, and improving the stability of the communication link. Thus, it can provide strong technical support for satellite communication.

[0055] In one embodiment, the spaceborne laser communication system 10 based on a flat-plate synthetic aperture can adopt advanced communication protocols such as TCP and IP to achieve long-distance and high-speed laser communication. And LDPC (Low-Density Parity-Check) coding and 16QAM (16 Quadrature Amplitude Modulation) modulation techniques can be adopted to improve the anti-interference ability and transmission rate during the communication process. In this embodiment, the spaceborne laser communication system 10 based on a flat-plate synthetic aperture can realize the emission of laser beams as follows:

[0056] Data encapsulation is achieved by the signal processor 12. Data encapsulation includes: dividing the data to be transmitted into data packets of a set size. Adding a packet header containing specific information before each data packet, where the specific information includes source address, destination address, sequence number, and other information. Generating LDPC for each data to detect transmission errors.

[0057] Channel coding is achieved by the signal processor 12. Channel coding includes: performing LDPC coding on each data packet, which can increase redundant information and improve the anti-interference ability. Interleaving the data after LDPC coding, which can reduce the impact caused by burst errors.

[0058] Data modulation is achieved by the signal processor 12. Data modulation includes: performing 16QAM modulation mapping on the encoded data packets and outputting modulation signals to improve spectral efficiency. Pulse shaping the output modulation signals to reduce out-of-band radiation.

[0059] The laser transmitter 16 converts the modulation signal into a laser signal and emits a laser beam. The laser beam forms multiple sub-beams through the beam splitter 17. After each sub-beam passes through the phase modulator 18, it is transmitted to the corresponding micro-lens 15 to be emitted to the target or other communication nodes.

[0060] The spaceborne laser communication system 10 based on the flat synthetic aperture can receive laser beams as follows:

[0061] The incident laser beam is divided into multiple sub-beams by the micro-lens array 13. After each sub-beam passes through the corresponding receiving optical path group 20, it is incident on the photodetector 19.

[0062] The photodetector 19 converts the optical signal into an electrical signal.

[0063] The signal processor 12 demodulates the electrical signal from the photodetector 19, and simultaneously performs time synchronization and carrier synchronization to ensure accurate demodulation.

[0064] The signal processor 12 performs de-interleaving processing on the demodulated data packets. And uses the LDPC decoding algorithm to correct errors in transmission.

[0065] Data de-encapsulation is achieved by the signal processor 12. Data de-encapsulation includes: checking the checksum of the data packet to confirm the integrity of the data. Removing the packet header after checking to extract the valid data. Recombining the data packets according to the sequence number to restore the original data. During this process, if an error is detected, a request for retransmission is sent to the sending end. The sending end can retransmit the lost or incorrect data packets according to the request.

[0066] In one embodiment, the spaceborne laser communication system 10 based on planar synthetic aperture can synchronize and calibrate signals between satellites or between a satellite and a ground station based on GPS to ensure the stability and reliability of the spaceborne laser communication system 10 and reduce the communication error rate. The synchronization and signal calibration specifically include the following steps:

[0067] The transmitting end generates a communication signal according to the received GPS time, modulates the communication signal onto a laser carrier, and transmits it to the receiving end. Among them, the timestamp of the communication signal is aligned with the timestamp of GPS. And the time reference of the modulation process of modulating the communication signal onto the laser carrier is synchronized with the GPS time.

[0068] The receiving end receives the communication signal, compares the time when the communication signal is received with the local GPS time, and calculates and determines the propagation delay of the communication signal. Among them, the receiving end can extract the timestamp in the communication signal and compare it with the local GPS time. The demodulation process of the receiving end can be adjusted according to the timestamp and the calculated propagation delay to ensure that the communication signal is correctly decoded. If there is a time deviation, the receiving end feeds back to the transmitting end for dynamic calibration.

[0069] See Figure 4 and Figure 5 As shown, the embodiment of the present invention provides a working method of a spaceborne laser communication system 10 based on planar synthetic aperture, which is applied to the spaceborne laser communication system 10 based on planar synthetic aperture. The working method includes:

[0070] S1: Encode the data to be transmitted through the signal processor 12, modulate the encoded data onto a laser beam, and emit the laser beam through the laser transmitter 16.

[0071] S2: Split the laser beam emitted by the laser transmitter 16 through the beam splitter 17, split the laser beam into multiple sub-beams, and after each sub-beam passes through the phase modulator 18, it is transmitted to the corresponding microlens 15;

[0072] S3: The multiple microlenses 15 of the microlens group 13 include multiple regions, each region includes at least two microlenses 15, the sub-beams emitted from at least two microlenses 15 in each region are coherently combined to form a combined beam pointing in a set direction; the pointing directions of the combined beams in different regions among the multiple regions are different. In this way, the spaceborne laser communication system 10 can realize the emission of laser beams, and at the same moment, multiple combined beams pointing in different directions can be formed simultaneously, so that multiple laser communication signals can be transmitted simultaneously. And the sub-beams emitted from at least two microlenses 15 in each region are coherently combined, which can ensure a high concentration when emitting the beam, improve the pointing accuracy and resolution of the emitted beam, and thus improve the transmission distance of the laser communication signal.

[0073] In one embodiment, by adjusting the phase modulators 18 corresponding to at least two microlenses 15 in each region, the phase difference between the sub-beams emitted from two adjacent microlenses 15 in each region is set to a set value, so that the sub-beams emitted from at least two microlenses 15 in each region are coherently combined. The coherent combination of the sub-beams emitted from at least two microlenses 15 in each region can be achieved by adjusting the phase modulators 18.

[0074] In one embodiment, the working method of the spaceborne laser communication system 10 further includes:

[0075] S4: The incident laser beam is split into multiple sub-beams by the microlens array 13, and after passing through the corresponding receiving optical path group 20, it is incident on the photodetector 19;

[0076] S5: The photodetector 19 converts the laser signals of the multiple sub-beams into electrical signals and transmits the electrical signals to the signal processor 12;

[0077] S6: The signal processor 12 processes the electrical signals output by the photodetector 19. In this way, the spaceborne laser communication system 10 can receive the laser beam, and the multiple microlenses 15 of the microlens array 13 can be equivalent to a virtual large aperture, effectively solving problems such as beam divergence, atmospheric interference, and large alignment difficulty in laser communication.

[0078] It should be understood that the various forms of the processes shown above can be used, steps can be reordered, added, or deleted. For example, the steps recorded in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and no limitation is made herein.

[0079] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A spaceborne laser communication system based on a flat-panel synthetic aperture type, characterized in that, It includes a flat plate structure, a signal processor, a microlens array, and a transmitting optical path group: The microlens array is arranged on the flat plate structure, and the microlens array includes a plurality of microlenses arranged in an array; The transmitting optical path group includes a laser emitter, a beam splitter, and a plurality of phase modulators; the phase modulators are correspondingly arranged with the microlenses; the signal processor is used to encode the data to be transmitted, modulate the encoded data onto the laser beam, and emit the laser beam through the laser emitter; the beam splitter is located on the optical path of the laser beam and is used to split the laser beam to form multiple sub-beams, and each sub-beam is transmitted to the corresponding microlens after passing through the phase modulator; The plurality of microlenses are divided into multiple regions, each region includes at least two microlenses, and the sub-beams emitted from at least two microlenses in each region are coherently combined to form a combined beam pointing in a set direction; the pointing directions of the combined beams in different regions among the multiple regions are different.

2. The spaceborne laser communication system based on a flat synthetic aperture as claimed in claim 1, wherein, The phase modulator is used to adjust the phase difference between the sub-beams emitted from two adjacent microlenses in each region and adjust the phase difference to a set value so that the sub-beams emitted from at least two microlenses in each region are coherently combined.

3. The spaceborne laser communication system based on planar synthetic aperture according to claim 1, wherein, It further includes a photodetector and a plurality of receiving optical path groups; The receiving optical path groups are correspondingly arranged with the microlenses. The incident laser beam is split into multiple sub-beams by the microlens array, and each sub-beam is incident on the photodetector after passing through the corresponding receiving optical path group. The photodetector converts the laser signals of the multiple sub-beams into electrical signals and transmits the electrical signals to the signal processor, and the signal processor processes the electrical signals.

4. The spaceborne laser communication system based on flat-panel synthetic aperture according to claim 3, characterized in that, The receiving optical path group includes a diaphragm, and each sub-beam is incident on the photodetector after passing through the diaphragm.

5. The spaceborne laser communication system based on a flat synthetic aperture according to claim 3, wherein The receiving optical path group includes a filter, and each sub-beam is incident on the photodetector after passing through the filter.

6. The spaceborne laser communication system based on a flat synthetic aperture according to claim 3, wherein The receiving optical path group includes a focusing lens, and each sub-beam passes through the focusing lens and is focused on the photodetector.

7. The spaceborne laser communication system based on planar synthetic aperture according to claim 3, wherein It further includes a fine-tuning mechanism, and the fine-tuning mechanism includes a controller and an adjustment component. The adjustment component is connected to the flat plate structure. The controller is used to rotate the flat plate structure through the adjustment component according to the intensity of the optical signal incident on the photodetector to increase the intensity of the optical signal received by the photodetector.

8. A working method of a spaceborne laser communication system based on flat panel synthetic aperture, characterized in that, It is applied to a spaceborne laser communication system based on a flat plate synthetic aperture type; the spaceborne laser communication system includes a signal processor, a microlens array, and a transmitting optical path group; the microlens array includes a plurality of microlenses arranged in an array; the transmitting optical path group includes a laser emitter, a beam splitter, and a plurality of phase modulators; the phase modulators are correspondingly arranged with the microlenses; the working method includes: Encoding the data to be transmitted by the signal processor, modulating the encoded data onto the laser beam, and emitting the laser beam through the laser emitter; The beam splitter is used to split the laser beam emitted by the laser emitter, dividing the laser beam into multiple sub-beams. After each sub-beam passes through the phase modulator, it is transmitted to the corresponding microlens. The multiple microlenses of the microlens array are divided into multiple regions. Each region includes at least two microlenses. The sub-beams emitted from at least two microlenses in each region are coherently combined to form a combined beam pointing in a set direction. The directions of the combined beams in different regions among the multiple regions are different.

9. The working method of the spaceborne laser communication system based on planar synthetic aperture according to claim 8, characterized in that, By adjusting the phase modulators corresponding to at least two microlenses in each region, the phase difference between the sub-beams emitted from two adjacent microlenses in each region is set to a set value, so that the sub-beams emitted from at least two microlenses in each region are coherently combined.

10. The working method of the spaceborne laser communication system based on the flat plate synthetic aperture type according to claim 8, characterized in that, The spaceborne laser communication system further includes a photodetector and multiple receiving optical path groups, which are arranged corresponding to the microlenses. The working method includes: The incident laser beam is split into multiple sub-beams by the microlens array, and after passing through the corresponding receiving optical path groups, it is incident on the photodetector. The photodetector converts the laser signals of the multiple sub-beams into electrical signals and transmits the electrical signals to the signal processor. The signal processor processes the electrical signals output by the photodetector.

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