Dual-state switchable common-aperture laser communication terminal

Abstract

The application discloses a dual-state switchable common-caliber laser communication terminal, belonging to the technical field of space laser communication, which comprises a transceiving common optical antenna, a dual-waveband transmitting unit, a main light path splitting component, a dual-waveband receiving unit and a tracking detection unit; the transceiving common optical antenna comprises a Cassegrain optical antenna and a two-dimensional galvanometer, the two-dimensional galvanometer is arranged between the Cassegrain optical antenna and the main light path splitting component, and is used for reflecting and adjusting the direction of the light beam inputted or outputted by the Cassegrain optical antenna; the dual-waveband transmitting unit comprises a first transmitting branch and a second transmitting branch; the single terminal of the application can be compatible with the working characteristics of two types of terminals in the first working state and the second working state. In a dynamic networking scene, it is not necessary to deploy two types of fixed terminals in a 1:1 proportion, so that the number of physical devices of the system can be effectively reduced, and the volume, weight, power consumption and cost of a load-limited carrier such as a satellite or a high-altitude platform can be significantly reduced.

Description

Technical Field

[0001] This invention belongs to the field of space laser communication and optical communication networking technology, specifically relating to a dual-state switchable common-aperture laser communication terminal. Background Technology

[0002] Space laser communication boasts significant advantages, including high transmission rates, large communication capacity, strong resistance to electromagnetic interference, excellent security, no need to occupy radio spectrum resources, and lightweight, low-power equipment. It is a core supporting technology for current integrated high-speed information transmission networks in space and air, low-Earth orbit satellite constellation networking, and high-altitude platform relay communication. With the increasing demands for dynamic satellite network topologies, mobile nodes, on-demand link access, and network resilience and reconfiguration, extremely high requirements are placed on the networking flexibility, link interoperability, equipment versatility, and redundancy fault tolerance of laser communication terminals.

[0003] Existing laser communication network architectures generally adopt a fixed pairing communication mode between two types of terminals, A and B, forming a rigid transmit-receive matching mechanism. Type A terminals are fixedly configured to transmit wavelength λ1 and receive wavelength λ2, while Type B terminals are fixedly configured to transmit wavelength λ2 and receive wavelength λ1. Network communication only supports cross-type link establishment between Type A and Type B terminals; optical link connection communication cannot be established between terminals of the same type. This fixed pairing mode can meet basic transmission requirements in static point-to-point fixed-point communication scenarios, but it has many inherent defects in large-scale dynamic networking scenarios.

[0004] First, the network has extremely poor flexibility and weak adaptability. Traditional terminals have fixed operating states at the factory, and the transmit and receive wavelengths and transmit / receive matching relationships cannot be changed. When the network topology changes, node positions are adjusted or new network nodes are added, problems such as terminal state mismatch, link failure, and communication interruption are very likely to occur. It cannot meet the networking requirements of nodes being able to access any location and links being able to reconfigure autonomously, which seriously limits the dynamic expansion capability of laser communication networks.

[0005] Secondly, the system has high equipment redundancy and significant overall load disadvantage. To ensure interoperability between all network nodes, the existing networking scheme must deploy Type A and Type B terminals in batches at a 1:1 ratio, doubling the number of networking devices. This significantly increases the size, weight, power consumption, and cost (SWaP-C) of payload-constrained carriers such as satellites and high-altitude platforms, which is not conducive to the large-scale and lightweight deployment of microsatellite constellations and distributed low-altitude networking equipment.

[0006] Secondly, the network's resilience and fault tolerance are insufficient. Existing fixed-state terminals lack state switching capabilities. When a batch of terminals of a certain type fail, are damaged, or links fail within the network, the remaining terminals cannot switch working states to reconstruct the communication link, which can easily cause local network paralysis. The overall network reliability and survivability cannot meet the requirements of military and high-reliability commercial networking.

[0007] Finally, the equipment suffers from poor versatility and upgradeability. The optical paths, transmit and receive parameters, and matching systems of traditional laser communication terminals are all fixed at the factory, making it impossible to adjust parameters or switch working modes on-orbit or in the field. This results in poor adaptability to complex communication scenarios with multiple rates, wavelengths, and network topologies, and the cost of later functional upgrades and system compatibility modifications is extremely high.

[0008] The existing switchable laser communication terminal solutions mostly adopt external optical switch switching, dual optical path parallel redundancy, and whole-machine module superposition. They generally suffer from problems such as large optical insertion loss, high switching delay, poor optical path stability, low overall integration, complex structure, and high power consumption. They can only achieve local parameter fine-tuning and cannot complete the overall seamless switching of the complete A / B bidirectional transmission and reception state, which is difficult to meet the needs of engineering and large-scale networking applications.

[0009] In summary, existing fixed-pair laser communication terminal units suffer from core problems such as rigid networking, high redundancy, poor survivability, and weak versatility. Existing switching improvement schemes, on the other hand, have technical defects such as high loss, poor stability, low integration, and inability to switch between complete states. Therefore, there is an urgent need for a laser communication terminal unit that is compact, switches quickly, has low optical path loss, and can seamlessly switch between dual working states online to solve the existing technical bottlenecks. Summary of the Invention

[0010] The technical problem to be solved by the present invention is how to provide a dual-state switchable common aperture laser communication terminal that can switch between the first working state and the second working state online at the microsecond level, realize dual-use and dynamic network reconstruction.

[0011] A dual-state switchable common-aperture laser communication terminal includes a shared optical antenna for transmitting and receiving, a dual-band transmitting unit, a main optical path beam splitter, a dual-band receiving unit, and a tracking and detection unit.

[0012] The shared optical antenna for transmitting and receiving includes a Cassegrain optical antenna and a two-dimensional galvanometer. The two-dimensional galvanometer is disposed between the Cassegrain optical antenna and the main optical path beam splitter, and is used to reflect and adjust the direction of the light beam input or output by the Cassegrain optical antenna.

[0013] The dual-band transmission unit includes a first transmission branch and a second transmission branch;

[0014] In the first transmitting branch, the output end of the first laser is connected to the input port of the first fiber optic looper via an optical fiber, and the output port of the first fiber optic looper is connected to the first fiber optic head via an optical fiber. The diverging beam output from the first fiber optic head is collimated into parallel light by the first collimating and focusing component, and is used to transmit communication light with a wavelength of λ1.

[0015] In the second transmitting branch, the output end of the second laser is connected to the input port of the second fiber optic looper via an optical fiber, and the output port of the second fiber optic looper is connected to the second fiber optic head via an optical fiber. The diverging beam output from the second fiber optic head is collimated into parallel light by the second collimating and focusing component, and is used to transmit communication light with a wavelength of λ2.

[0016] The main optical path beam splitting component includes a wavelength beam splitter, a first energy beam splitter, and a second energy beam splitter;

[0017] The wavelength beam splitter is disposed in the downstream optical path of the two-dimensional galvanometer and is used to reflect parallel light of wavelength λ1 to the first energy beam splitter and transmit parallel light of wavelength λ2 to the second energy beam splitter.

[0018] The first energy beam splitter is disposed on the reflected light path of the wavelength beam splitter, and is used to transmit parallel light of wavelength λ1, and to reflect and transmit the received light of wavelength λ1 incident on the first energy beam splitter according to a preset ratio.

[0019] The second energy beam splitter is disposed on the transmission optical path of the wavelength beam splitter, and is used to transmit parallel light of wavelength λ2, and to reflect and transmit the received light of wavelength λ2 incident on the second energy beam splitter according to a preset ratio;

[0020] The dual-band receiving unit includes an optical switch and a communication detector;

[0021] The output terminals of the first fiber optic looper and the second fiber optic looper are respectively connected to the two input terminals of the optical switch, and the output terminal of the optical switch is connected to the communication detector;

[0022] The communication detector is used to perform photoelectric conversion and data demodulation on the optical signal output by the optical switch;

[0023] The tracking and detection unit includes a focusing lens, a first narrowband filter, a second narrowband filter, a spatial beam combiner, and an infrared array camera.

[0024] The first narrowband filter is used to transmit only wavelength λ1 light, and the second narrowband filter is used to transmit only wavelength λ2 light;

[0025] The reflected beam reflected by the first energy beam splitter is filtered sequentially by the first narrowband filter, the spatial beam combiner, and the focusing lens, and then converged to the infrared array camera;

[0026] The reflected beam reflected by the second energy beam splitter is filtered sequentially by the second narrowband filter, the spatial beam combiner, and the focusing lens, and then converged to the infrared array camera;

[0027] The infrared array camera is used to calculate the position of the light spot and output the deviation signal to achieve real-time target tracking by controlling the two-dimensional galvanometer in a closed loop.

[0028] The terminal has a first operating state and a second operating state; the first operating state is configured to transmit communication light with wavelength λ1 and receive communication light with wavelength λ2; the second operating state is configured to transmit communication light with wavelength λ2 and receive communication light with wavelength λ1.

[0029] The terminal selects the first laser or the second laser via electronic control and simultaneously controls the optical switch to turn on the corresponding receiving branch, thereby switching between the first working state and the second working state.

[0030] The electronic control mode switching includes: controlling the opening and closing of the first laser and the second laser, and controlling the path selection of the optical switch.

[0031] The terminal device autonomously triggers the switching between the first working state and the second working state based on networking instructions, link status information, or manual instructions.

[0032] It also includes a signal modulation and demodulation module, which is adapted to communication signals of two wavelengths, λ1 and λ2. When the terminal is operating in the first operating state, the signal modulation and demodulation module is used to modulate the λ1 wavelength transmitted signal and demodulate the λ2 wavelength received signal. When the terminal is operating in the second operating state, the signal modulation and demodulation module is used to modulate the λ2 wavelength transmitted signal and demodulate the λ1 wavelength received signal, so that the communication rate and signal quality of the terminal remain stable and consistent before and after the switching.

[0033] When the terminal is in its first operating state, the λ1 wavelength communication light is collimated into parallel light by the first fiber optic looper, the first fiber optic head, and the first collimating and focusing assembly. It then passes through the first energy beam splitter and is reflected by the wavelength beam splitter before being emitted outwards via the two-dimensional galvanometer and the Cassegrain optical antenna. The externally received λ2 wavelength communication light passes through the Cassegrain optical antenna and the two-dimensional galvanometer, is transmitted through the wavelength beam splitter, and is incident on the second energy beam splitter. The second energy beam splitter splits the λ2 wavelength communication light into a transmitted beam and a reflected beam. The transmitted beam is focused by the second collimating and focusing assembly into the second fiber optic head and then coupled to the communication detector via the second fiber optic looper and an optical switch to complete communication demodulation. The reflected beam is filtered by the second narrowband filter, then converged by the spatial light combiner and the focusing lens to the infrared array camera for spot tracking.

[0034] When the terminal switches to the second operating state, the λ2 wavelength communication light is collimated into parallel light by the second fiber optic looper, the second fiber optic head, and the second collimating and focusing assembly. It then passes through the second energy beam splitter and, after being transmitted through the wavelength beam splitter, is sequentially transmitted through the two-dimensional galvanometer and the Cassegrain optical antenna. The externally received λ1 wavelength communication light, after passing through the Cassegrain optical antenna and the two-dimensional galvanometer, is reflected by the wavelength beam splitter and incident on the first energy beam splitter. The first energy beam splitter splits the λ1 wavelength communication light into a transmitted beam and a reflected beam. The transmitted beam is focused by the first collimating and focusing assembly into the first fiber optic head and sequentially coupled to the communication detector via the first fiber optic looper and the optical switch to complete communication demodulation. The reflected beam is sequentially filtered by the first narrowband filter, a spatial beam combiner, and a focusing lens, and converged to the infrared array camera for spot tracking.

[0035] The first working state and the second working state are mutually exclusive working modes; the terminal working in the first working state and the terminal working in the second working state establish a bidirectional communication link; the terminal switching process does not interrupt the power supply of the whole machine, and the switching delay is less than or equal to 1 microsecond.

[0036] A relay collimating lens is provided in the optical path between the Cassegrain optical antenna and the two-dimensional galvanometer. The relay collimating lens is used to convert and collimate the light beam emitted from the Cassegrain optical antenna before transmitting it to the two-dimensional galvanometer.

[0037] The beneficial effects of this invention are: a single terminal unit can be compatible with the working characteristics of both traditional first and second working states of terminals. In dynamic networking scenarios, it is not necessary to deploy two types of fixed terminal devices in batches at a 1:1 ratio, which can effectively reduce the number of physical devices in the system and significantly reduce the volume, weight, power consumption, and cost of payload-constrained carriers such as satellites and high-altitude platforms, thus meeting the requirements of large-scale and lightweight networking. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of a dual-state switchable common-aperture laser communication terminal according to the present invention.

[0039] Figure 2 This is an optical path diagram of the first working state of a dual-state switchable common aperture laser communication terminal of the present invention.

[0040] Figure 3 This is an optical path diagram of the second working state of a dual-state switchable common aperture laser communication terminal according to the present invention.

[0041] In the diagram: 1-Cassegrain optical antenna, 2-Two-dimensional galvanometer, 3-Wavelength beam splitter, 4-First energy beam splitter, 5-Second energy beam splitter, 6-First collimating and focusing assembly, 7-Second collimating and focusing assembly, 8-First fiber optic head, 9-Second fiber optic head, 10-First laser, 11-Second laser, 12-First fiber optic circulator, 13-Second fiber optic circulator, 14-Optical switch, 15-Communication detector, 16-Spatial optical combiner, 17-First narrowband filter, 18-Second narrowband filter, 19-Focusing lens, 20-Infrared array camera, 21-Relay collimating lens. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings.

[0043] A dual-state switchable common-aperture laser communication terminal, such as Figure 1 As shown, it includes a shared optical antenna for transmitting and receiving, a dual-band transmitting unit, a main optical path beam splitter, a dual-band receiving unit, and a tracking and detection unit;

[0044] The transceiver shared optical antenna includes a Cassegrain optical antenna 1 and a two-dimensional galvanometer 2. The two-dimensional galvanometer 2 is disposed between the Cassegrain optical antenna 1 and the main optical path beam splitter, and is used to reflect and adjust the direction of the light beam input or output by the Cassegrain optical antenna 1.

[0045] The dual-band transmission unit includes a first transmission branch and a second transmission branch;

[0046] In the first transmitting branch, the output end of the first laser 10 is connected to the input port of the first fiber optic looper 12 via an optical fiber, and the output port of the first fiber optic looper 12 is connected to the first fiber optic head 8 via an optical fiber. The diverging beam output by the first fiber optic head 8 is collimated into parallel light by the first collimating and focusing component 6, and is used to transmit communication light with a wavelength of λ1.

[0047] In the second transmission branch, the output end of the second laser 11 is connected to the input port of the second fiber optic looper 13 via an optical fiber, and the output port of the second fiber optic looper 13 is connected to the second fiber optic head 9 via an optical fiber. The diverging beam output by the second fiber optic head 9 is collimated into parallel light by the second collimating and focusing component 7, and is used to transmit communication light with a wavelength of λ2.

[0048] The main optical path beam splitting assembly includes a wavelength beam splitter 3, a first energy beam splitter 4, and a second energy beam splitter 5;

[0049] The wavelength beam splitter 3 is disposed in the downstream optical path of the two-dimensional galvanometer 2, and is used to reflect the parallel light of wavelength λ1 to the first energy beam splitter 4 and transmit the parallel light of wavelength λ2 to the second energy beam splitter 5.

[0050] The first energy beam splitter 4 is disposed on the reflected light path of the wavelength beam splitter 3, and is used to transmit parallel light of wavelength λ1, and to reflect and transmit the received light of wavelength λ1 incident on the first energy beam splitter 4 according to a preset ratio.

[0051] The second energy beam splitter 5 is disposed on the transmission optical path of the wavelength beam splitter 3, and is used to transmit parallel light of wavelength λ2, and to reflect and transmit the received light of wavelength λ2 incident on the second energy beam splitter 5 according to a preset ratio.

[0052] The dual-band receiving unit includes an optical switch 14 and a communication detector 15;

[0053] The output terminals of the first fiber optic looper 12 and the second fiber optic looper 13 are respectively connected to the two input terminals of the optical switch 14, and the output terminal of the optical switch 14 is connected to the communication detector 15.

[0054] The communication detector 15 is used to perform photoelectric conversion and data demodulation on the optical signal output by the optical switch 14;

[0055] The tracking and detection unit includes a focusing lens 19, a first narrowband filter 17, a second narrowband filter 18, a spatial light combiner 16, and an infrared array camera 20.

[0056] The first narrowband filter 17 is used to transmit only wavelength λ1 light, and the second narrowband filter 18 is used to transmit only wavelength λ2 light;

[0057] The reflected beam from the first energy beam splitter 4 is filtered sequentially by the first narrowband filter 17, the spatial beam combiner 16, and the focusing lens 19, and then converged to the infrared array camera 20; the reflected beam from the second energy beam splitter 5 is filtered sequentially by the second narrowband filter 18, the spatial beam combiner 16, and the focusing lens 19, and then converged to the infrared array camera 20.

[0058] The infrared array camera 20 is used to calculate the position of the light spot and output the deviation signal to achieve real-time target tracking by controlling the two-dimensional galvanometer 2 in a closed loop.

[0059] The terminal has a first operating state and a second operating state; the first operating state is configured to transmit communication light with wavelength λ1 and receive communication light with wavelength λ2; the second operating state is configured to transmit communication light with wavelength λ2 and receive communication light with wavelength λ1.

[0060] The terminal selects the first laser 10 or the second laser 11 through electronic control and simultaneously controls the optical switch 14 to conduct the corresponding receiving branch, thereby switching between the first working state and the second working state.

[0061] The electronic control mode switching includes: controlling the opening and closing of the first laser 10 and the second laser 11, and controlling the path selection of the optical switch 14.

[0062] The terminal device autonomously triggers the switching between the first working state and the second working state based on networking instructions, link status information, or manual instructions.

[0063] It also includes a signal modulation and demodulation module, which is adapted to communication signals of two wavelengths, λ1 and λ2. When the terminal is operating in the first operating state, the signal modulation and demodulation module is used to modulate the λ1 wavelength transmitted signal and demodulate the λ2 wavelength received signal. When the terminal is operating in the second operating state, the signal modulation and demodulation module is used to modulate the λ2 wavelength transmitted signal and demodulate the λ1 wavelength received signal, so that the communication rate and signal quality of the terminal remain stable and consistent before and after the switching.

[0064] When the terminal is in the first working state, the λ1 wavelength communication light is collimated into parallel light by the first fiber optic looper 12, the first fiber optic head 8, and the first collimating and focusing assembly 6, passes through the first energy beam splitter 4, and is reflected by the wavelength beam splitter 3, and is then emitted outward by the two-dimensional galvanometer 2 and the Cassegrain optical antenna 1 in sequence; the externally received λ2 wavelength communication light passes through the Cassegrain optical antenna 1 and the two-dimensional galvanometer 2, is transmitted through the wavelength beam splitter 3, and is incident on the second energy beam splitter 5; the second energy beam splitter 5 splits the λ2 wavelength communication light into a transmitted beam and a reflected beam; the transmitted beam is focused by the second collimating and focusing assembly 7 into the second fiber optic head 9, and is coupled to the communication detector 15 in sequence by the second fiber optic looper 13 and the optical switch 14 to complete communication demodulation; the reflected beam is filtered by the second narrowband filter 18, converged by the spatial light combiner 16 and the focusing lens 19 to the infrared array camera 20 for spot tracking.

[0065] When the terminal switches to the second working state, the λ2 wavelength communication light is collimated into parallel light by the second fiber optic looper 13, the second fiber optic head 9, and the second collimating and focusing assembly 7, then passes through the second energy beam splitter 5, and is transmitted through the wavelength beam splitter 3, and is then emitted outwards by the two-dimensional galvanometer 2 and the Cassegrain optical antenna 1 in sequence; the externally received λ1 wavelength communication light is reflected by the wavelength beam splitter 3 after passing through the Cassegrain optical antenna 1 and the two-dimensional galvanometer 2, and is incident on the first energy beam splitter 4; the first energy beam splitter 4 splits the λ1 wavelength communication light into a transmitted beam and a reflected beam; the transmitted beam is focused by the first collimating and focusing assembly 6 into the first fiber optic head 8, and is coupled to the communication detector 15 in sequence through the first fiber optic looper 12 and the optical switch 14 to complete communication demodulation; the reflected beam is filtered by the first narrowband filter 17, converged by the spatial light combiner 16 and the focusing lens 19 to the infrared array camera 20 for spot tracking.

[0066] The first working state and the second working state are mutually exclusive working modes; the terminal working in the first working state and the terminal working in the second working state establish a bidirectional communication link; the terminal switching process does not interrupt the power supply of the whole machine, and the switching delay is less than or equal to 1 microsecond.

[0067] A relay collimating lens 21 is provided in the optical path between the Cassegrain optical antenna 1 and the two-dimensional galvanometer 2. The relay collimating lens 21 is used to convert and collimate the light beam emitted from the Cassegrain optical antenna 1 and then transmit it to the two-dimensional galvanometer 2.

[0068] Example 1: This example provides a dual-state switchable common-aperture laser communication terminal, selecting a typical communication band, i.e., setting λ1 wavelength to 1550nm and λ2 wavelength to 1530nm. The first narrowband filter is a 1550nm narrowband filter, and the second narrowband filter is a 1530nm narrowband filter. In this example, the preferred splitting ratio of the first and second energy beam splitters is: 90% transmittance and 10% reflectivity, which allows 90% of the incident light energy to be used for communication and 10% for beam tracking. In other examples, this splitting ratio can be adjusted within the range of 85%~90% transmittance and 10%~15% reflectivity according to the communication distance and light intensity requirements. The entire device adopts an integrated transceiver common-aperture optical structure. A relay collimating lens 21 is also provided in the optical path between the Cassegrain optical antenna 1 and the two-dimensional galvanometer 2, used to project the beam within the antenna aperture to the two-dimensional galvanometer 2 after relay collimation. In the dual-band transmitting unit, the first laser 10, with a wavelength of 1550nm, is connected to the input port of the first fiber optic looper 12 via optical fiber; the second laser 11, with a wavelength of 1530nm, is connected to the input port of the second fiber optic looper 13 via optical fiber.

[0069] In the main optical path beam splitter assembly, the wavelength beam splitter 3 is positioned downstream of the two-dimensional galvanometer 2 at a certain tilt angle. Because the wavelength beam splitter 3 has high reflectivity for 1550nm wavelength light and high transmittance for 1530nm wavelength light, it constructs two separate channels in the optical path: one is the first energy beam splitter 4 located on the reflective optical path of the wavelength beam splitter 3, and the other is the second energy beam splitter 5 located on the transmittance optical path of the wavelength beam splitter 3.

[0070] When the terminal switches to the first working state, i.e., emitting 1550nm light and receiving 1530nm light, such as Figure 2 As shown, the working situation is as follows.

[0071] Transmitting optical path: The control terminal activates the first laser 10 and deactivates the second laser 11. The 1550nm communication light emitted by the first laser 10 passes through the first fiber optic loop 12 and the first fiber optic connector 8, and is collimated into parallel light by the first collimating and focusing assembly 6. This parallel light passes through the first energy beam splitter 4, reaches the wavelength beam splitter 3, and after being reflected by the wavelength beam splitter 3, is emitted outward sequentially through the two-dimensional galvanometer 2 and the Cassegrain optical antenna 1.

[0072] Receiving and Tracking Optical Path: The terminal receives 1530nm communication light from an external source. This light enters through the Cassegrain optical antenna 1, is adjusted by the two-dimensional galvanometer 2, passes through the wavelength splitter 3, and is incident on the second energy splitter 5. The second energy splitter 5 splits the 1530nm received light into a transmitted beam and a reflected beam at a ratio of 90:10.

[0073] The transmitted beam with 90% energy is focused by the second collimating and focusing assembly 7 into the second fiber optic head 9. After being selected by the second fiber optic circulator 13 and the optical switch 14, it is coupled to the communication detector 15 to complete photoelectric conversion and data demodulation. The reflected beam with 10% energy passes sequentially through a 1530nm narrowband filter 18 to remove ambient background stray light, a spatial light combiner 16, and a focusing lens 19 before converging onto the infrared array camera 20. The infrared array camera 20 calculates the spot miss distance in real time and outputs a deviation signal to perform real-time optical axis correction using a closed-loop control of the two-dimensional galvanometer 2, ensuring uninterrupted communication link.

[0074] When the terminal switches to the second operating state, i.e., emitting 1530nm light and receiving 1550nm light, such as Figure 3 As shown, the control terminal starts the second laser 11, turns off the first laser 10, and the optical switch 14 performs synchronous switching:

[0075] Transmitting optical path: The 1530nm communication light emitted by the second laser 11 passes through the second fiber optic looper 13 and the second fiber optic connector 9, and is collimated into parallel light by the second collimating and focusing assembly 7. After passing through the second energy beam splitter 5, the parallel light reaches the wavelength beam splitter 3, and after being transmitted through the wavelength beam splitter 3, it is emitted outward sequentially through the two-dimensional galvanometer 2 and the Cassegrain optical antenna 1.

[0076] Receiving and Tracking Optical Path: The terminal receives 1550nm communication light from an external source. This light enters through the Cassegrain optical antenna 1, is adjusted by the two-dimensional galvanometer 2, and is reflected by the wavelength splitter 3 before being incident on the first energy splitter 4. The first energy splitter 4 also splits the 1550nm received light into a transmitted beam and a reflected beam at a ratio of 90:10.

[0077] The transmitted beam with 90% energy is focused by the first collimating and focusing assembly 6 into the first fiber optic head 8, and after passing through the first fiber optic circulator 12 and the optical switch 14, it is coupled to the communication detector 15 to complete communication demodulation. The reflected beam with 10% energy is filtered sequentially by the 1550nm narrowband filter 17, the spatial light combiner 16, and the focusing lens 19, and then converged to the infrared array camera 20 for spot position calculation and closed-loop tracking control of the two-dimensional galvanometer 2.

[0078] The terminal unit has a built-in control board for performing dual-state electronic switching. The switching process includes controlling the on / off state of the first laser 10 and the second laser 11, and synchronously controlling the path selection of the optical switch 14. During this process, the power supply and core control program of the entire unit remain uninterrupted. The optical system requires no adjustment of any mechanical moving parts, resulting in extremely short switching delays, preferably within 1 microsecond (1μs). This switching action can be autonomously triggered by the control board based on network topology instructions, real-time link signal-to-noise ratio / packet loss rate information, or external manual commands. To accommodate rapid switching between dual wavelengths, the terminal unit is also equipped with a signal modulation and demodulation module. In the first operating state, this module modulates the 1550nm transmitted signal and demodulates the 1530nm received signal; in the second operating state, the module modulates the 1530nm transmitted signal and demodulates the 1550nm received signal, thereby ensuring that the communication rate and signal quality remain stable and consistent before and after the switching.

[0079] Example 2: The main difference between this example and Example 1 is that, depending on the actual link budget, the splitting ratio of the first and second energy beam splitters can be set to 85% transmittance and 15% reflectivity to increase the energy of the tracking optical path and further meet the needs of long-distance, weak light signal scenarios. Simultaneously, the selection of wavelengths λ1 and λ2 can be based on spectrum resource allocation, for example, using free-space communication bands such as λ1=1064nm and λ2=980nm. Its optical path structure, switching control logic, and working principle are the same as in Example 1, and will not be repeated here.

[0080] This invention has illustrated its principles and implementation methods using specific examples. The descriptions of these embodiments are merely illustrative of the method and its core ideas; furthermore, those skilled in the art will recognize that modifications may be made to the specific implementation methods and application scope based on the principles of this invention. Therefore, the content of this specification should not be construed as limiting the invention.

Claims

1. A dual-state switchable common-aperture laser communication terminal, characterized in that, It includes a shared optical antenna for transmitting and receiving, a dual-band transmitting unit, a main optical path beam splitter, a dual-band receiving unit, and a tracking and detection unit; The shared optical antenna for transmitting and receiving includes a Cassegrain optical antenna and a two-dimensional galvanometer. The two-dimensional galvanometer is disposed between the Cassegrain optical antenna and the main optical path beam splitter, and is used to reflect and adjust the direction of the light beam input or output by the Cassegrain optical antenna. The dual-band transmission unit includes a first transmission branch and a second transmission branch; In the first transmitting branch, the output end of the first laser is connected to the input port of the first fiber optic looper via an optical fiber, and the output port of the first fiber optic looper is connected to the first fiber optic head via an optical fiber. The diverging beam output from the first fiber optic head is collimated into parallel light by the first collimating and focusing component, and is used to transmit communication light with a wavelength of λ1. In the second transmitting branch, the output end of the second laser is connected to the input port of the second fiber optic looper via an optical fiber, and the output port of the second fiber optic looper is connected to the second fiber optic head via an optical fiber. The diverging beam output from the second fiber optic head is collimated into parallel light by the second collimating and focusing component, and is used to transmit communication light with a wavelength of λ2. The main optical path beam splitting component includes a wavelength beam splitter, a first energy beam splitter, and a second energy beam splitter; The wavelength beam splitter is disposed in the downstream optical path of the two-dimensional galvanometer and is used to reflect parallel light of wavelength λ1 to the first energy beam splitter and transmit parallel light of wavelength λ2 to the second energy beam splitter. The first energy beam splitter is disposed on the reflected light path of the wavelength beam splitter, and is used to transmit parallel light of wavelength λ1, and to reflect and transmit the received light of wavelength λ1 incident on the first energy beam splitter according to a preset ratio. The second energy beam splitter is disposed on the transmission optical path of the wavelength beam splitter, and is used to transmit parallel light of wavelength λ2, and to reflect and transmit the received light of wavelength λ2 incident on the second energy beam splitter according to a preset ratio; The dual-band receiving unit includes an optical switch and a communication detector; The output terminals of the first fiber optic looper and the second fiber optic looper are respectively connected to the two input terminals of the optical switch, and the output terminal of the optical switch is connected to the communication detector; The communication detector is used to perform photoelectric conversion and data demodulation on the optical signal output by the optical switch; The tracking and detection unit includes a focusing lens, a first narrowband filter, a second narrowband filter, a spatial beam combiner, and an infrared array camera. The first narrowband filter is used to transmit only wavelength λ1 light, and the second narrowband filter is used to transmit only wavelength λ2 light; The reflected beam reflected by the first energy beam splitter is filtered sequentially by the first narrowband filter, the spatial beam combiner, and the focusing lens, and then converged to the infrared array camera; The reflected beam reflected by the second energy beam splitter is filtered sequentially by the second narrowband filter, the spatial beam combiner, and the focusing lens, and then converged to the infrared array camera; The infrared array camera is used to calculate the position of the light spot and output the deviation signal to achieve real-time target tracking by controlling the two-dimensional galvanometer in a closed loop.

2. The dual-state switchable common-aperture laser communication terminal according to claim 1, characterized in that, The terminal has a first operating state and a second operating state; the first operating state is configured to transmit communication light with wavelength λ1 and receive communication light with wavelength λ2; the second operating state is configured to transmit communication light with wavelength λ2 and receive communication light with wavelength λ1.

3. The dual-state switchable common-aperture laser communication terminal according to claim 2, characterized in that, The terminal selects the first laser or the second laser via electronic control and simultaneously controls the optical switch to turn on the corresponding receiving branch, thereby switching between the first working state and the second working state.

4. The dual-state switchable common-aperture laser communication terminal according to claim 3, characterized in that, The electronic control mode switching includes: controlling the opening and closing of the first laser and the second laser, and controlling the path selection of the optical switch.

5. The dual-state switchable common-aperture laser communication terminal according to claim 2, characterized in that, The terminal device autonomously triggers the switching between the first working state and the second working state based on networking instructions, link status information, or manual instructions.

6. The dual-state switchable common-aperture laser communication terminal according to claim 2, characterized in that, When the terminal is in its first operating state, the λ1 wavelength communication light is collimated into parallel light by the first fiber optic looper, the first fiber optic head, and the first collimating and focusing assembly. It then passes through the first energy beam splitter and is reflected by the wavelength beam splitter before being emitted outwards via the two-dimensional galvanometer and the Cassegrain optical antenna. The externally received λ2 wavelength communication light passes through the Cassegrain optical antenna and the two-dimensional galvanometer, is transmitted through the wavelength beam splitter, and is incident on the second energy beam splitter. The second energy beam splitter splits the λ2 wavelength communication light into a transmitted beam and a reflected beam. The transmitted beam is focused by the second collimating and focusing assembly into the second fiber optic head and then coupled to the communication detector via the second fiber optic looper and an optical switch to complete communication demodulation. The reflected beam is filtered by the second narrowband filter, then converged by the spatial light combiner and the focusing lens to the infrared array camera for spot tracking.

7. The dual-state switchable common-aperture laser communication terminal according to claim 2, characterized in that, When the terminal switches to the second operating state, the λ2 wavelength communication light is collimated into parallel light by the second fiber optic looper, the second fiber optic head, and the second collimating and focusing assembly. It then passes through the second energy beam splitter and, after being transmitted through the wavelength beam splitter, is sequentially transmitted through the two-dimensional galvanometer and the Cassegrain optical antenna. The externally received λ1 wavelength communication light, after passing through the Cassegrain optical antenna and the two-dimensional galvanometer, is reflected by the wavelength beam splitter and incident on the first energy beam splitter. The first energy beam splitter splits the λ1 wavelength communication light into a transmitted beam and a reflected beam. The transmitted beam is focused by the first collimating and focusing assembly into the first fiber optic head and sequentially coupled to the communication detector via the first fiber optic looper and the optical switch to complete communication demodulation. The reflected beam is sequentially filtered by the first narrowband filter, a spatial beam combiner, and a focusing lens, and converged to the infrared array camera for spot tracking.

8. The dual-state switchable common-aperture laser communication terminal according to claim 2, characterized in that, The first working state and the second working state are mutually exclusive working modes; the terminal working in the first working state and the terminal working in the second working state establish a bidirectional communication link; the terminal switching process does not interrupt the power supply of the whole machine, and the switching delay is less than or equal to 1 microsecond.

9. The dual-state switchable common-aperture laser communication terminal according to claim 1, characterized in that, A relay collimating lens is provided in the optical path between the Cassegrain optical antenna and the two-dimensional galvanometer. The relay collimating lens is used to convert and collimate the light beam emitted from the Cassegrain optical antenna before transmitting it to the two-dimensional galvanometer.

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