Small laser communication terminal, method, device and medium based on wavelength division multiplexing

Abstract

The present invention proposes a small laser communication terminal, method, device and medium based on wavelength division multiplexing. It relates to the field of communication technology. The communication terminal includes a multi-wavelength light source module, a wavelength division multiplexer module, an integrated signal processing module, a precision pointing and tracking module, a high-sensitivity light receiving module and an optical system module. The present invention uses a wavelength division multiplexer to perform wavelength division multiplexing of the communication terminal, reduces signal crosstalk between different wavelengths, and increases the reliability and stability of communication.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a small laser communication terminal, method, device and medium based on wavelength division multiplexing (WDM). Background Art

[0002] With the rapid development of space exploration and satellite communications, traditional radio frequency communication methods are facing the problems of spectrum congestion and limited transmission rate. Laser communication has become a powerful supplement to satellite-to-ground communication due to its high bandwidth, strong anti-interference ability and low signal loss. Especially in the context of the growing demand for deep space exploration and high data rate transmission, the application of wavelength division multiplexing technology can effectively improve the data transmission capacity of satellite-to-ground laser communication systems. However, the existing satellite-to-ground laser communication systems face problems such as high system complexity, heavy payload weight, and high power consumption when implementing wavelength division multiplexing. Summary of the invention

[0003] Aiming at the current situation of satellites in orbit operated by existing commercial remote sensing satellite companies, the present invention proposes a small laser communication terminal, method, device and medium based on wavelength division multiplexing. The communication terminal adopts the technical route of small-aperture transmission antenna, multiple seed light sources, detectors and fast-reflecting mirrors to complete a small laser communication terminal with low weight and low power consumption.

[0004] The present invention is realized by the following technical scheme. The present invention proposes a small laser communication terminal based on wavelength division multiplexing, wherein the communication terminal comprises a multi-wavelength light source module, a wavelength division multiplexer module, an integrated signal processing module, a precision pointing and tracking module, a high-sensitivity light receiving module and an optical system module;

[0005] Multi-wavelength light source module: includes multiple lasers with different wavelengths and electro-optic modulators, which convert the electrical signal transmitted from the integrated signal processing module into multiple optical signals with different wavelengths to achieve multi-channel parallel transmission;

[0006] Wavelength division multiplexer module: used to combine multiple optical signals of different wavelengths into a single optical fiber for transmission, optimizing the spectrum utilization of the signal;

[0007] Integrated signal processing module: completes the functions of data modulation, coding, demodulation and decoding. It modulates and codes the data signals sent by the satellite into baseband signals of different paths, i.e. electrical signals, and coordinates the work of each module, including communication terminal initialization, status monitoring and communication with the satellite platform;

[0008] Precision pointing and tracking module: Use the fast-reflection mirror and the capture and tracking detector to complete the capture and tracking of the communication terminal and the ground station. Use the capture and tracking control module to realize the detector image recognition and the control of the fast-reflection mirror, and finally achieve stable signal transmission;

[0009] High-sensitivity optical receiving module: used to detect spatial laser signals and convert amplitude-modulated laser signals into electrical signals;

[0010] Optical system module: gathers large-aperture spatial beam signals into small-aperture spatial beam signals, collimates the optical fiber signals output by the optical fiber amplifier into spatial signal light, and completes the separation of spatial beam transmission and reception, and separates the signal light from the capture and tracking beam.

[0011] Furthermore, the wavelength division multiplexer module includes a combiner and an optical fiber amplifier. The wavelength division multiplexer module combines multiple seed light sources through the electro-optical modulator into one optical signal through the combiner, and sends it to the optical fiber amplifier. The optical signal is amplified by the ytterbium-doped optical fiber amplifier. The working bandwidth of the ytterbium-doped optical fiber amplifier covers the design wavelength, and the combined optical signal can be amplified to the design size according to needs. The wavelength division multiplexer module completes the aggregation and amplification of multiple wavelength beams.

[0012] Furthermore, the precision pointing and tracking module includes a capture and tracking detector, a fast reflex mirror and a capture and tracking control module, wherein the capture and tracking detector is used to receive the beacon light of the ground station, obtain the light spot imaging angular error and light spot detection, and provide the fast reflex mirror with precise tracking position information; the fast reflex mirror is a piezoelectric galvanometer, and the piezoelectric galvanometer is controlled in a closed loop according to the output angular error of the detector; the capture and tracking control module completes the processing of the detector image data, and uses an algorithm to complete the extraction of the tracking error and the control of the satellite-to-ground tracking process.

[0013] Furthermore, the integrated signal processing module includes functions for completing modulation and encoding of downlink data, and demodulating and decoding the electrical signal received by the high-sensitivity optical receiving module.

[0014] Furthermore, the high-sensitivity optical receiving module adopts an APD detector, and actively controls the temperature and working bias voltage of the APD detector, directly receives the spatial laser signal, and completes the conversion of the laser signal to the electrical signal with high gain.

[0015] Furthermore, the optical system module includes an optical antenna, a transceiver color separation plate, a spectrometer, a focusing lens group 1, a focusing lens group 2, a filter, an M2 reflector and a transmitting collimator; wherein the optical antenna completes the contraction of a large-aperture space beam signal into a small-aperture space beam signal to facilitate the miniaturization design of the relay optical unit, and at the same time expands the small-aperture transmitting beam of the relay optical unit into a large-aperture beam to reduce the divergence angle of the transmitting beam; the transceiver color separation plate is used to isolate different transmitting and receiving light wavelengths; the spectrometer splits the received uplink ground communication light, one beam enters a high-sensitivity light receiving module, and the other part is captured and tracked by a detector; the focusing lens group is used to converge light; the filter is used to filter out stray light outside the working band; the M2 reflector is used to fold the light inside the relay optical path; the transmitting collimator transmits the light beam in the optical fiber into the free space light through the optical system module.

[0016] Furthermore, each laser has high stability and low noise characteristics, adopts the EML 1550nm band laser used in terrestrial optical fiber communication, and makes the wavelength difference between different wavelengths 0.4nm.

[0017] The present invention also proposes a communication method of a small laser communication terminal based on the wavelength division multiplexing, and the method is specifically as follows:

[0018] The integrated signal processing module completes the functions of data modulation, coding, demodulation and decoding. It modulates and codes the data signals sent by the satellite into baseband signals, i.e. electrical signals, of different paths, and coordinates the work of each module, including communication terminal initialization, status monitoring and communication with the satellite platform.

[0019] Multiple lasers with different wavelengths and electro-optic modulators convert the electrical signals transmitted from the integrated signal processing module into multiple optical signals with different wavelengths to achieve multi-channel parallel transmission;

[0020] The wavelength division multiplexer module combines multiple optical signals of different wavelengths into a single optical fiber for transmission, optimizing the spectrum utilization of the signal;

[0021] The precision pointing and tracking module uses a fast-reflection mirror and a capture and tracking detector to complete the capture and tracking of the communication terminal and the ground station, and uses the capture and tracking control module to realize the detector image recognition and the control of the fast-reflection mirror, ultimately achieving stable signal transmission;

[0022] The high-sensitivity optical receiving module detects the spatial laser signal and converts the amplitude-modulated laser signal into an electrical signal;

[0023] The optical system module gathers the large-aperture spatial beam signal into a small-aperture spatial beam signal, and collimates the optical fiber signal output by the optical fiber amplifier into spatial signal light, while completing the separation of spatial beam transmission and reception, and separating the signal light from the capture and tracking beam.

[0024] The present invention also proposes an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the communication method of the small laser communication terminal based on wavelength division multiplexing are implemented.

[0025] The present invention also proposes a computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the steps of a communication method for a small laser communication terminal based on wavelength division multiplexing.

[0026] Beneficial effects of the present invention:

[0027] 1. The present invention significantly improves the communication data transmission rate and enhances the system scalability through wavelength division multiplexing technology.

[0028] 2. The present invention uses only a large-angle fast-reflection mirror as a coarse and fine tracking actuator to complete the capture, tracking and alignment of the satellite and the ground station, eliminates the servo rotation mechanism of the traditional satellite-borne laser payload, and reduces the weight of the laser payload.

[0029] 3. The present invention utilizes a wavelength division multiplexer to perform wavelength division multiplexing of communication terminals, thereby reducing signal crosstalk between different wavelengths and increasing the reliability and stability of communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0031] Figure 1 This is the schematic diagram of a small laser communication terminal based on wavelength division multiplexing;

[0032] Figure 2 This is a block diagram of the optical system modules. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] The present invention proposes a small laser communication terminal based on wavelength division multiplexing, wherein the communication terminal comprises a multi-wavelength light source module, a wavelength division multiplexer module, an integrated signal processing module, a precision pointing and tracking module, a high-sensitivity light receiving module and an optical system module;

[0035] Multi-wavelength light source module: includes multiple lasers with different wavelengths and electro-optic modulators, which convert the electrical signal transmitted from the integrated signal processing module into multiple optical signals with different wavelengths to achieve multi-channel parallel transmission;

[0036] Wavelength division multiplexer module: used to combine multiple optical signals of different wavelengths into a single optical fiber for transmission, optimizing the spectrum utilization of the signal;

[0037] Integrated signal processing module: completes the functions of data modulation, coding, demodulation and decoding. It modulates and codes the data signals sent by the satellite into baseband signals of different paths, i.e. electrical signals, and coordinates the work of each module, including communication terminal initialization, status monitoring and communication with the satellite platform;

[0038] Precision pointing and tracking module: Use the fast-reflection mirror and the capture and tracking detector to complete the capture and tracking of the communication terminal and the ground station. Use the capture and tracking control module to realize the detector image recognition and the control of the fast-reflection mirror, and finally achieve stable signal transmission;

[0039] High-sensitivity optical receiving module: used to detect spatial laser signals and convert amplitude-modulated laser signals into electrical signals;

[0040] Optical system module: gathers large-aperture spatial beam signals into small-aperture spatial beam signals, collimates the optical fiber signals output by the optical fiber amplifier into spatial signal light, and completes the separation of spatial beam transmission and reception, and separates the signal light from the capture and tracking beam.

[0041] The wavelength division multiplexer module includes a combiner and a fiber amplifier. The wavelength division multiplexer module combines multiple seed light sources through the electro-optical modulator into one optical signal through the combiner, and sends it to the fiber amplifier. The optical signal is amplified by the ytterbium-doped fiber amplifier. The working bandwidth of the ytterbium-doped fiber amplifier covers the design wavelength, and the combined optical signal can be amplified to the design size according to demand. The wavelength division multiplexer module completes the aggregation and amplification of multiple wavelength beams.

[0042] The precision pointing and tracking module includes a capture and tracking detector, a fast reflection mirror and a capture and tracking control module. The capture and tracking detector is used to receive the beacon light from the ground station, obtain the spot imaging angular error and spot detection, and provide the fast reflection mirror with precise tracking position information. The fast reflection mirror is a piezoelectric galvanometer, which is closed-loop controlled according to the output angular error of the detector. The capture and tracking control module completes the processing of the detector image data, uses algorithms to extract the tracking error and control the satellite-to-ground tracking process, thereby completing the capture and high-precision tracking of the communication terminal.

[0043] The integrated signal processing module includes the functions of completing the modulation and encoding of the downlink data, and demodulating and decoding the electrical signal received by the high-sensitivity optical receiving module.

[0044] The high-sensitivity optical receiving module adopts APD (Avalanche Photo Diode) detector, and actively controls the temperature and working bias voltage of the APD detector, directly receives the spatial laser signal, and completes the conversion of the laser signal to the electrical signal with high gain.

[0045] The optical system module comprises an optical antenna, a transceiver color separation plate, a beam splitter, a focusing lens group 1, a focusing lens group 2, a filter, an M2 reflector and a transmitting collimator; wherein the transmission optical antenna completes the contraction of a large-aperture space beam signal into a small-aperture space beam signal, so as to facilitate the miniaturization design of the relay optical unit, and at the same time expands the small-aperture transmitting beam of the relay optical unit into a large-aperture beam, so as to reduce the divergence angle of the transmitting beam; the transceiver color separation plate is used to isolate different transmitting and receiving light wavelengths; the beam splitter splits the received uplink ground communication light, one beam enters a high-sensitivity light receiving module, and the other part is captured and tracked by a detector; the focusing lens group is used to converge light; the filter is used to filter out stray light outside the working band; the M2 reflector is used to fold the light inside the relay optical path; the transmitting collimator transmits the light beam in the optical fiber into the free space light through the optical system module.

[0046] Each laser has high stability and low noise characteristics. It adopts the EML 1550nm band laser used in terrestrial optical fiber communications, and the wavelength difference between different wavelengths is 0.4nm, which increases the number of expandable paths while minimizing the impact on the optical system.

[0047] The present invention also proposes a communication method of a small laser communication terminal based on the wavelength division multiplexing, and the method is specifically as follows:

[0048] The integrated signal processing module completes the functions of data modulation, coding, demodulation and decoding. It modulates and codes the data signals sent by the satellite into baseband signals, i.e. electrical signals, of different paths, and coordinates the work of each module, including communication terminal initialization, status monitoring and communication with the satellite platform.

[0049] Multiple lasers with different wavelengths and electro-optic modulators convert the electrical signals transmitted from the integrated signal processing module into multiple optical signals with different wavelengths to achieve multi-channel parallel transmission;

[0050] The wavelength division multiplexer module combines multiple optical signals of different wavelengths into a single optical fiber for transmission, optimizing the spectrum utilization of the signal;

[0051] The precision pointing and tracking module uses a fast-reflection mirror and a capture and tracking detector to complete the capture and tracking of the communication terminal and the ground station, and uses the capture and tracking control module to realize the detector image recognition and the control of the fast-reflection mirror, ultimately achieving stable signal transmission;

[0052] The high-sensitivity optical receiving module detects the spatial laser signal and converts the amplitude-modulated laser signal into an electrical signal;

[0053] The optical system module gathers the large-aperture spatial beam signal into a small-aperture spatial beam signal, and collimates the optical fiber signal output by the optical fiber amplifier into spatial signal light, while completing the separation of spatial beam transmission and reception, and separating the signal light from the capture and tracking beam.

[0054] Example

[0055] like Figure 1 As shown, a wavelength division multiplexing light and small laser communication terminal for satellite-to-ground laser communication is mainly composed of multi-wavelength light source module, wavelength division multiplexer module, integrated signal processing module, precision pointing and tracking module, high-sensitivity light receiving module and optical system module. The various functional modules of the terminal are integrated together through spatial optical paths, optical fibers and electrical signal lines.

[0056] The multi-wavelength light source module includes two lasers with different wavelengths, 1540.16nm and 1540.56nm respectively. Each laser has high stability and low noise characteristics. The temperature of the two lasers is controlled by the controller in a closed loop to ensure the stability of the output wavelength of the multi-wavelength module.

[0057] The wavelength division multiplexer module includes a combiner and a fiber amplifier. The wavelength division multiplexer module combines two seed light sources obtained by modulating the electro-optical modulators with wavelengths of 1540.16nm and 1540.56nm into an optical signal through a combiner and sends it to the fiber amplifier. The optical signal is amplified to 30dBm by the ytterbium-doped fiber amplifier. The working bandwidth of the ytterbium-doped fiber amplifier covers 1535nm~1565nm, and the entire optical power output fluctuation range is less than 1%. The power consumption of this part is less than 10W.

[0058] Precision pointing and tracking module, the whole precision pointing and tracking module is composed of a low-power SOC processing architecture, using a CMOS (Complementary Metal-Oxide-Semiconductor Image Sensor) detector, model CMV4000, to detect the 808nm wavelength beacon light emitted from the ground, with a pixel size of 5.5μm, a pixel size of 2048×2048, a response wavelength of 400nm-1000nm, and a field of view that can cover the capture uncertainty area; piezoelectric ceramic galvanometer is used for tracking and precision pointing control, and its main advantages are small size, low power consumption and high precision. FSM is driven by four displacement amplification piezoelectric drivers, which are composed of a piezoelectric ceramic stack and an elastic shell. The piezoelectric galvanometer in the present invention has an execution range of 17.5mrad and a closed-loop resolution of 1μrad. A resistance strain gauge sensor is integrated inside, and its control and drive are completed by the precision tracking system. The power consumption of the module is less than 5W.

[0059] The integrated signal processing module is mainly implemented by a high-speed data processing board based on Xilinx, including 2-way high-speed baseband modulation drive circuits and a V7-690T FPGA chip to complete the baseband information encoding and modulation functions of the downlink data. After processing the received satellite platform service data through channel coding, phase mapping, physical layer framing, shaping filtering and orthogonal modulation, the 2-way baseband signal is modulated by 2-way electro-optical modulators and sent to the wavelength division multiplexer module. At the same time, the uplink baseband signal of the satellite laser ground station connected to the high-sensitivity optical receiving module is demodulated. At the same time, the communication terminal initialization, capture and tracking system status monitoring and satellite platform interface communication functions are completed. The power consumption of this module is less than 30W.

[0060] The high-sensitivity optical receiving module uses a low-noise APD (Avalanche Photo Diode) detector to detect laser signals. Its response is 2500kV / W@808nm. The detector outputs a current signal, which is converted into a voltage signal using a TIA amplifier and amplified at the same time. After being limited by the filter noise bandwidth, it is output to the integrated signal processing module to complete the laser signal reception and detection. The power consumption of the entire module is less than 2W.

[0061] The optical system module consists of Figure 2As shown, it consists of an optical antenna, an M2 reflector, a transceiver color splitter, a transmitting collimator, a filter, a beam splitter, a focusing group 1, and a focusing group 2. The optical system module completes beam compression through an optical antenna with a compression and expansion ratio of 5 times, realizes the spatial beam transmission and reception separation of the downlink transmission wavelength and the uplink signal light through a color splitter (1550 / 808), suppresses stray light through a narrowband filter (808nm±5nm), completes the folding of the light path through an M2 reflector, and the beam splitter is 9:1, which is used to complete the energy distribution of the APD and the CMOS camera. Two focusing lens groups complete the system energy convergence, and the transmitting collimator collimates the optical fiber signal output by the optical fiber amplifier into a spatial light signal, which is transmitted to the laser ground station.

[0062] In summary, the present invention cleverly integrates advanced wavelength division multiplexing technology and successfully creates a satellite-to-ground laser communication terminal with multi-channel transmission capabilities. The terminal is exquisitely designed, compact in size, and the power consumption of the whole machine is controlled below 50 watts. The weight is even lighter than 5 kilograms, which fully reflects the design concept of lightweight and low energy consumption. The satellite-to-ground laser communication terminal adopts a highly integrated circuit design scheme, and its multi-channel transmission function greatly improves the efficiency and flexibility of data transmission, meets the needs of satellite-to-ground communication for high speed and large capacity, and opens up a broader application prospect for satellite-to-ground communication.

[0063] The present invention also proposes an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the communication method of the small laser communication terminal based on wavelength division multiplexing are implemented.

[0064] The present invention also proposes a computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the steps of a communication method for a small laser communication terminal based on wavelength division multiplexing.

[0065] The memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read only memory (ROM), a programmable read only memory (PROM), an erasable programmable read only memory (EPROM), an electrically erasable programmable read only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchlink DRAM (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory of the method described in the present invention is intended to include, but is not limited to, these and any other suitable types of memory.

[0066] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a digital video disc (DVD)), or a semiconductor medium (eg, a solid state disc (SSD)).

[0067] In the implementation process, each step of the above method can be completed by an integrated logic circuit of hardware in a processor or an instruction in the form of software. The steps of the method disclosed in conjunction with the embodiment of the present application can be directly embodied as a hardware processor for execution, or a combination of hardware and software modules in a processor for execution. The software module can be located in a storage medium mature in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in a memory, and the processor reads the information in the memory and completes the steps of the above method in conjunction with its hardware. To avoid repetition, it is not described in detail here.

[0068] It should be noted that the processor in the embodiment of the present application may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method embodiment may be completed by an integrated logic circuit of hardware in the processor or an instruction in the form of software. The above processor may be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component. The methods, steps and logic block diagrams disclosed in the embodiments of the present application may be implemented or executed. The general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc. The steps of the method disclosed in the embodiment of the present application may be directly embodied as being executed by a hardware decoding processor, or may be executed by a combination of hardware and software modules in a decoding processor. The software module may be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in a memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

[0069] The above is a detailed introduction to a small laser communication terminal, method, device and medium based on wavelength division multiplexing proposed in the present invention. Specific examples are used in this article to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for general technical personnel in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A small laser communication terminal based on wavelength division multiplexing, characterized in that: The communication terminal includes a multi-wavelength light source module, a wavelength division multiplexer module, an integrated signal processing module, a precision pointing and tracking module, a high-sensitivity light receiving module and an optical system module; Multi-wavelength light source module: includes multiple lasers with different wavelengths and electro-optic modulators, which convert the electrical signal transmitted from the integrated signal processing module into multiple optical signals with different wavelengths to achieve multi-channel parallel transmission; Wavelength division multiplexer module: used to combine multiple optical signals of different wavelengths into a single optical fiber for transmission, optimizing the spectrum utilization of the signal; the wavelength division multiplexer module includes a combiner and an optical fiber amplifier. The wavelength division multiplexer module combines multiple seed light sources through the electro-optical modulator into one optical signal through the combiner, and sends it to the optical fiber amplifier, and amplifies the optical signal through the ytterbium-doped fiber amplifier. The working bandwidth of the ytterbium-doped fiber amplifier covers the design wavelength, and the combined optical signal can be amplified to the design size according to the demand. The wavelength division multiplexer module completes the aggregation and amplification of multiple wavelength beams; Integrated signal processing module: completes the functions of data modulation, coding, demodulation and decoding. It modulates and codes the data signals sent by the satellite into baseband signals of different paths, i.e. electrical signals, and coordinates the work of each module, including communication terminal initialization, status monitoring and communication with the satellite platform; Precision pointing and tracking module: Use the fast-reflection mirror and the capture and tracking detector to complete the capture and tracking of the communication terminal and the ground station. Use the capture and tracking control module to realize the detector image recognition and the control of the fast-reflection mirror, and finally achieve stable signal transmission; High-sensitivity optical receiving module: used to detect spatial laser signals and convert amplitude-modulated laser signals into electrical signals; Optical system module: gathers large-aperture spatial beam signals into small-aperture spatial beam signals, collimates the optical fiber signals output by the optical fiber amplifier into spatial signal light, and completes the separation of spatial beam transmission and reception, and separation of signal light and capture tracking beam; The precision pointing and tracking module includes a capture and tracking detector, a fast reflection mirror and a capture and tracking control module. The capture and tracking detector is used to receive the beacon light from the ground station, obtain the spot imaging angular error and spot detection, and provide the fast reflection mirror with precise tracking position information. The fast reflection mirror is a piezoelectric galvanometer, which is closed-loop controlled according to the output angular error of the detector. The capture and tracking control module completes the processing of the detector image data, and uses algorithms to extract the tracking error and control the satellite-to-ground tracking process.

2. The communication terminal according to claim 1, characterized in that: The integrated signal processing module includes the functions of completing the modulation and encoding of the downlink data, and demodulating and decoding the electrical signal received by the high-sensitivity optical receiving module.

3. The communication terminal according to claim 1, characterized in that: The high-sensitivity optical receiving module adopts an APD detector, and actively controls the temperature and working bias voltage of the APD detector, directly receives the spatial laser signal, and completes the conversion of the laser signal to the electrical signal with high gain.

4. The communication terminal according to claim 1, characterized in that: The optical system module comprises an optical antenna, a transceiver color separation plate, a beam splitter, a focusing lens group 1, a focusing lens group 2, a filter, an M2 reflector and a transmitting collimator; wherein the optical antenna completes the contraction of a large-aperture space beam signal into a small-aperture space beam signal, so as to facilitate the miniaturization design of the relay optical unit, and at the same time expands the small-aperture transmitting beam of the relay optical unit into a large-aperture beam, so as to reduce the divergence angle of the transmitting beam; the transceiver color separation plate is used to isolate different transmitting and receiving light wavelengths; the beam splitter splits the received uplink ground communication light, one beam enters a high-sensitivity light receiving module, and the other part is captured and tracked by a detector; the focusing lens group is used to converge light; the filter is used to filter out stray light outside the working band; the M2 reflector is used to fold the light inside the relay optical path; the transmitting collimator transmits the light beam in the optical fiber into the free space light through the optical system module.

5. The communication terminal according to claim 1, characterized in that: Each laser has high stability and low noise characteristics. It adopts the EML 1550nm band laser used in terrestrial optical fiber communications, and the wavelength difference between different wavelengths is 0.4nm.

6. A communication method based on the small laser communication terminal based on wavelength division multiplexing according to claim 1, characterized in that: The method is specifically as follows: The integrated signal processing module completes the functions of data modulation, coding, demodulation and decoding. It modulates and codes the data signals sent by the satellite into baseband signals of different paths, i.e. electrical signals, and coordinates the work of each module, including communication terminal initialization, status monitoring and communication with the satellite platform; Multiple lasers with different wavelengths and electro-optic modulators convert the electrical signals transmitted from the integrated signal processing module into multiple optical signals with different wavelengths to achieve multi-channel parallel transmission; The wavelength division multiplexer module combines multiple optical signals of different wavelengths into a single optical fiber for transmission, optimizing the spectrum utilization of the signal; the wavelength division multiplexer module includes a combiner and an optical fiber amplifier. The wavelength division multiplexer module combines multiple seed light sources through an electro-optical modulator into one optical signal through a combiner, and sends it to the optical fiber amplifier, and amplifies the optical signal through an ytterbium-doped optical fiber amplifier. The working bandwidth of the ytterbium-doped optical fiber amplifier covers the design wavelength, and the combined optical signal can be amplified to the design size according to demand. The wavelength division multiplexer module completes the aggregation and amplification of multiple wavelength beams; The precision pointing and tracking module uses a fast-reflection mirror and a capture and tracking detector to complete the capture and tracking of the communication terminal and the ground station, and uses the capture and tracking control module to realize the detector image recognition and the control of the fast-reflection mirror, ultimately achieving stable signal transmission; The high-sensitivity optical receiving module detects the spatial laser signal and converts the amplitude-modulated laser signal into an electrical signal; The optical system module gathers the large-aperture spatial beam signal into a small-aperture spatial beam signal, and collimates the optical fiber signal output by the optical fiber amplifier into spatial signal light, while completing the separation of spatial beam transmission and reception, and separating the signal light from the capture and tracking beam.

7. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to claim 6 are implemented.

8. A computer-readable storage medium for storing computer instructions, characterized in that: When the computer instructions are executed by a processor, the steps of the method according to claim 6 are implemented.

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