Optical phased array based fast link establishment laser communication method and system

Abstract

This invention relates to the field of wireless laser communication technology, specifically disclosing a rapid link establishment laser communication method and system based on an optical phased array. A rapid link establishment laser communication system based on an optical phased array includes an active transmitting terminal and a cat's-eye reverse modulation laser communication terminal. The active transmitting terminal is used to transmit uplink optical signals and includes a control processing unit, a laser driver, a laser, a collimating beam expander, and a spatial light modulator arranged sequentially. The cat's-eye reverse modulation laser communication terminal is used to receive uplink optical signals and feed back downlink optical signals, and includes a cat's-eye optical system, a beam splitter, a spatial light modulator, a second photodetector, and a control processing unit. This solves the problem of difficult link establishment in existing wireless laser communication systems.

Description

Technical Field

[0001] This invention relates to the field of wireless laser communication technology, specifically to a rapid link establishment laser communication method and system based on an optical phased array. Background Technology

[0002] With the development of information technology, the demand for high-speed and secure data transmission is becoming increasingly urgent. Traditional microwave links suffer from limitations such as bandwidth constraints and susceptibility to interference, failing to meet the information transmission requirements under conditions of strong electromagnetic interference. Wireless laser communication, using lasers as the communication carrier, offers advantages such as high security and strong resistance to electromagnetic interference, making it one of the important development directions for secure communication under conditions of strong electromagnetic interference.

[0003] Existing typical wireless laser communication systems are limited by the beam divergence angle, requiring two communication terminals to establish a communication link through a complex aiming, acquisition, and tracking process. This results in low link establishment efficiency, severely limiting the applicability of wireless laser communication. Designing a laser communication system capable of rapidly establishing a link is an effective means to solve the problem of high-capacity, high-speed, and secure data transmission under conditions of strong electromagnetic interference. Summary of the Invention

[0004] To address the difficulty in establishing links in existing wireless laser communication systems, the first objective of this invention is to provide a rapid link establishment laser communication system based on an optical phased array. This system employs an active transmitting terminal based on an optical phased array and a large-field-of-view cat's-eye inverse modulation laser communication terminal based on the cat's-eye effect as active and passive information nodes, respectively. Optical phased array technology improves the acquisition, tracking, and alignment process at the active end, while inverse modulation technology eliminates the acquisition, tracking, and aiming process at the passive information node. This significantly reduces link establishment time and enables rapid link establishment.

[0005] The second objective of this invention is to provide a rapid link establishment laser communication method based on an optical phased array.

[0006] To achieve the first objective, the first technical solution of the present invention is: a fast link-building laser communication system based on an optical phased array, comprising an active transmitting terminal and a cat's eye reverse modulation laser communication terminal;

[0007] The active transmitting terminal is used to transmit uplink optical signals and includes a control processing unit, a laser driver, a laser, a collimating beam expander, and a spatial light modulator arranged in sequence.

[0008] The cat-eye reverse modulation laser communication terminal is used to receive uplink optical signals and feedback downlink optical signals, and includes a cat-eye optical system, a beam splitter, a spatial light modulator, a second photodetector, and a control and processing unit.

[0009] Preferably, the active transmitting terminal is also used to receive downlink optical signals, and further includes a large field-of-view receiving lens, a first photodetector, and a signal acquisition unit arranged sequentially along the direction of the downlink optical signal.

[0010] Preferably, the active transmitting terminal further includes a phase controller for performing phase shift control on the spatial light modulator, and for receiving and transmitting phase shift signals based on the electrical signals of the control processing unit and the spatial light modulator.

[0011] Preferably, the spatial light modulator modulates the phase of each point in the uplink plane wave space to form an uplink communication beam that is emitted to the cat's eye optical system.

[0012] Preferably, in the cat-eye reverse modulation laser communication terminal, the uplink communication beam passes through the cat-eye optical system and is split by a beam splitter to form two uplink optical signals, which are respectively focused on the spatial light modulator and the second photodetector.

[0013] Preferably, the second photodetector generates a detection signal, which is then processed by a control system to generate a downlink modulation signal, thereby controlling the spatial light modulator to generate a reverse-modulated reflected light signal.

[0014] Preferably, the uplink communication beam scanning range generated by the active transmitting terminal can cover the uncertain area where the cat-eye reverse modulation laser communication terminal is located and the receiving field of view of the large field of view receiving lens.

[0015] Preferably, the active transmitting terminal is located within the effective field of view of the large field-of-view cat's eye reverse modulation laser communication terminal.

[0016] Preferably, the laser is a narrow linewidth laser.

[0017] To achieve the second objective, the second technical solution of the present invention is: a fast link establishment laser communication method based on an optical phased array, comprising:

[0018] The control and processing unit in the active transmitting terminal controls the laser to emit an uplink communication laser through the laser driver. The communication laser is collimated and expanded by the collimating beam expander to become an uplink plane wave, which is then irradiated by the spatial light modulator. The phase controller generates a specific phase shift signal to control the spatial light modulator to adjust the phase of each point in space of the uplink plane wave, thereby forming an uplink communication beam.

[0019] The uplink communication beam scans the uncertain area. When the uplink communication beam is scanned to the cat's eye reverse modulation laser communication terminal, the uplink communication beam is split by the cat's eye optical system through the beam splitter and focused on the spatial light modulator and the second photodetector, respectively.

[0020] The second photodetector generates a detection signal, which is then processed by a control and processing system to generate a downlink modulated signal.

[0021] The control spatial light modulator generates a reverse-modulated reflected light signal, which is reflected back through the cat's eye optical system to the large field-of-view receiving lens in the active transmitting terminal, focused on the first photodetector for photoelectric conversion, and sent to the control processing unit for processing to complete the link establishment.

[0022] The beneficial effects of the above technical solution are as follows:

[0023] This invention provides a rapid link-establishment laser communication system based on an optical phased array. The active transmitting terminal based on the optical phased array can quickly form a specific directional beam to scan the uncertain area where the passive terminal is located by using a spatial light modulator to adjust the phase of each point in the plane wave space. In this example, the system can complete the scanning coverage of 32×32 equally spaced points within a range of 0.21°×0.21° within 1 second.

[0024] Because the cat-eye effect-based large field-of-view cat-eye reverse modulation laser communication terminal utilizes the original path return characteristic of the incident communication beam, it ensures that the reverse reflected communication beam can always strictly return to the active terminal, thus eliminating the scanning and tracking process of the cat-eye terminal. It can quickly establish a communication link with the active terminal within the field of view. In this example, the active transmitting terminal based on the optical phased array can quickly establish a link with the cat-eye effect-based large field-of-view cat-eye reverse modulation laser communication terminal located within an uncertainty range of 0.21°×0.21° within 1 second.

[0025] Based on the cat's eye effect, a large field-of-view cat's eye reverse modulation laser communication terminal transmits downlink OOK signals. An actual measured 500kbps OOK signal is as follows: Figure 3 As shown. The entire link lasted approximately three minutes, with error-free transmission. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A schematic diagram of a fast link-establishment laser communication system based on an optical phased array, provided as an embodiment of the present invention;

[0028] Figure 2 An embodiment of the present invention provides an active transmitting terminal based on an optical phased array, which uses an uplink scanning beam formed by a spatial light modulator.

[0029] Figure 3A 500kbps OOK signal was provided for experimental transmission as an embodiment of the present invention. Detailed Implementation

[0030] The embodiments of this application will be described in further detail below. Obviously, the described embodiments are only a part of the embodiments of this application, and not an exhaustive list of all embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0031] The terms “first,” “second,” etc. (if present) in the specification and claims are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated (if present) or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion, such as a process, method, system, product, or apparatus that comprises a series of steps or units, not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0033] Example 1

[0034] One embodiment of the present invention provides a fast link establishment laser communication system based on an optical phased array, the structural schematic diagram of which is shown below. Figure 1As shown, it includes an active transmitting terminal 1 and a cat's eye reverse modulation laser communication terminal 2. In the active transmitting terminal 1 based on an optical phased array, the control processing unit 1-0 is an industrial control computer. The industrial control computer generates a TTL signal with a maximum modulation frequency of 3kHz and inputs the TTL signal to the external trigger port of the laser driver 1-1. In this embodiment, the laser 1-2 is a 532nm semiconductor single-longitudinal-mode continuous laser with an output power of 50mW, a divergence angle of 1mrad, and a beam diameter of 1.2mm. The collimating beam expander 1-4 has an output diameter of 20mm and a transmittance of 95%. The spatial light modulator 1-6 uses a Meadowlark Optics liquid crystal spatial light modulator with a response time of less than 0.6ms, a resolution of 1024×1024, an aperture of 17.4mm×17.4mm, and a unit size of 17μm. The phase controller 1-7 uses a matching controller capable of controlling the phase of the spatial light modulator 1-6 within the range of 0~2π. The large field-of-view receiving lens 1-10 has a receiving aperture of 20mm, a transmittance of 90%, and forms a field of view of 5mrad. The first photodetector 1-11 uses a Thorlabs silicon photodiode with a minimum detectable power of 100nW. In the large field-of-view cat-eye reverse modulation laser communication terminal 2 based on the cat-eye effect, the cat-eye optical system 2-1 has a diameter of 2cm, an effective field of view of 30°, and a transmittance of 90%. The beam splitter 2-2 has a transmittance of 90% and a reflectivity of 10%. The focal plane is placed with a microelectromechanical system array as a spatial light modulator 2-3, a four-quadrant detector is used as the second photodetector 2-4, and an FPGA is used as the control and processing system 2-6.

[0035] When the system is working, the active transmitting terminal 1 based on the optical phased array is controlled and processed by an industrial control computer 1-0. Based on the cat's eye effect, the large field of view cat's eye inverse modulation laser communication terminal 2 uses prior knowledge of the orientation. According to the agreed capture, tracking and aiming protocol, it generates a TTL-coded communication pulse signal and inputs it into the driver 1-1 to control the laser 1-2 to emit a pulsed uplink communication laser 1-3. After passing through the collimating and beam expander 1-4, it becomes an uplink plane wave 1-5 and illuminates the liquid crystal spatial light modulator 1-6 at a vertical angle. According to the capture, tracking and aiming strategy, the phase controller 1-7 generates a specific phase shift signal 1-8 to control the spatial light modulator 1-6 to adjust the phase of each point in space of the uplink plane wave 1-5, forming an uplink communication beam 1-9 to quickly scan the uncertain area. Figure 2This invention utilizes an active transmitting terminal based on an optical phased array to generate an uplink scanning beam using a spatial light modulator. When the uplink communication beam 1-9 is scanned to a large field-of-view cat-eye reverse modulation laser communication terminal 2 based on the cat-eye effect, the cat-eye optical system 2-1 focuses the uplink communication beam 1-9 onto the spatial light modulator 2-3 and the second photodetector 2-4, located at the focal plane, respectively, via a beam splitter 2-2. The second photodetector 2-4 generates a detection signal 2-5, which is processed and analyzed by a control processing unit 2-6, which is an FPGA control processing system. After processing and analysis by the control processing unit 2-6, a downlink modulation signal 2-7 is generated according to the agreed acquisition, tracking, and aiming protocol. This controls the spatial light modulator 2-3 to generate a reverse modulation light signal 2-8, which is reflected back to the active transmitting terminal 1 based on the optical phased array via the cat-eye optical system 2-1. The large field-of-view receiving lens 1-10 receives the reverse modulation light signal 2-8, focuses it onto the photodetector 1-11, performs photoelectric conversion, and then sends it to the control processing unit 1-0 for processing, thus completing the link establishment. Based on the cat's eye effect, a large field-of-view cat's eye reverse modulation laser communication terminal transmits downlink OOK signals. An actual measured 500kbps OOK signal is as follows: Figure 3 As shown. The entire link lasted approximately three minutes, with error-free transmission.

[0036] This invention also provides a method for rapid link establishment laser communication using a rapid link establishment laser communication system based on an optical phased array. The rapid link establishment laser communication system based on an optical phased array is used to establish the link. This includes a control processing unit 1-0 in an active transmitting terminal 1 controlling a laser 1-2 to emit an uplink communication laser 1-3 via a laser driver 1-1. The communication laser 1-3 is collimated and expanded by a beam expander 1-4 to become an uplink plane wave 1-5, which illuminates a spatial light modulator 1-6. A phase controller 1-7 generates a specific phase shift signal 1-8 to control the spatial light modulator 1-6 to adjust the phase of the uplink plane wave 1-5 at various points in space, forming an uplink communication beam 1-9. The uplink communication beam 1-9 scans an uncertain region. When it scans the cat's eye reverse modulation laser communication terminal 2, the uplink communication beam 1-9 is split by a beam splitter 2-2 via a cat's eye optical system 2-1, and focused onto the spatial light modulator 2-3 and the second photodetector 2-4, respectively. In this process, the second photodetector 2-4 generates a detection signal 2-5, which is then processed by the control and processing system 2-6 to generate a downlink modulation signal 2-7. The control spatial light modulator 2-3 generates a reverse-modulated reflected light signal 2-8, which is reflected through the cat's eye optical system 2-1 to the large field-of-view receiving lens 1-10 in the active transmitting terminal 1. The signal is then focused onto the first photodetector 1-11 for photoelectric conversion and sent to the control and processing unit 1-0 for processing, thus completing the link establishment.

[0037] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A rapid link-establishment laser communication system based on an optical phased array, characterized in that, It includes an active transmitting terminal (1) and a cat's eye reverse modulation laser communication terminal (2); The active transmitting terminal (1) is used to transmit uplink optical signals and includes a control processing unit (1-0), a laser driver (1-1), a laser (1-2), a collimating beam expander (1-4), and a spatial light modulator (1-6) arranged in sequence. The cat-eye reverse modulation laser communication terminal (2) is used to receive uplink optical signals and feedback downlink optical signals, including a cat-eye optical system (2-1), a beam splitter (2-2), a spatial light modulator (2-3), a second photodetector (2-4), and a control processing unit (2-6). The active transmitting terminal (1) is also used to receive downlink optical signals, and includes a large field-of-view receiving lens (1-10), a first photodetector (1-11) and a signal acquisition unit (15) arranged sequentially along the downlink optical signal direction. The active transmitting terminal (1) further includes a phase controller (1-7) for performing phase shift control on the spatial light modulator (1-6) and receiving and transmitting phase shift signals (1-8) based on the electrical signals of the control processing unit (1-0) and the spatial light modulator (1-6); Link establishment is accomplished using a rapid link-establishment laser communication system based on optical phased arrays; including: The control processing unit (1-0) in the active transmitting terminal (1) uses the azimuth prior knowledge of the large field of view cat's eye reverse modulation laser communication terminal (2) based on the cat's eye effect. According to the agreed capture tracking aiming protocol, it generates a TTL encoded communication pulse signal and inputs it into the laser driver (1-1) to control the laser (1-2) to emit an uplink communication laser (1-3). The communication laser (1-3) becomes an uplink plane wave (1-5) through the collimating beam expander (1-4) and illuminates the spatial light modulator (1-6). According to the capture tracking aiming strategy, the phase controller (1-7) generates a specific phase shift signal (1-8) to control the spatial light modulator (1-6) to adjust the phase of each point in space of the uplink plane wave (1-5) to form an uplink communication beam (1-9). The uplink communication beam (1-9) scans the uncertain area. When it scans the cat's eye reverse modulation laser communication terminal (2), the uplink communication beam (1-9) is split by the cat's eye optical system (2-1) through the beam splitter (2-2) and focused on the spatial light modulator (2-3) and the second photodetector (2-4) respectively. The second photodetector (2-4) generates a detection signal (2-5), which is processed and analyzed by the control processing unit (2-6) and then generates a downlink modulation signal (2-7) according to the agreed capture, tracking and aiming protocol. The control spatial light modulator (2-3) generates a reverse modulated reflected light signal (2-8), which is reflected back through the cat's eye optical system (2-1) to the large field-of-view receiving lens (1-10) in the active transmitting terminal (1), focused on the first photodetector (1-11) for photoelectric conversion, and sent to the control processing unit (1-0) for processing to complete the link establishment; The uplink communication beam (1-9) generated by the active transmitting terminal (1) can cover the uncertain area where the cat-eye reverse modulation laser communication terminal (2) is located and the receiving field of view of the large field of view receiving lens (1-10); The active transmitting terminal (1) is located within the effective field of view of the large field-of-view cat-eye reverse modulation laser communication terminal (2).

2. The rapid link establishment laser communication system based on optical phased array according to claim 1, characterized in that, The lasers (1-2) are narrow linewidth lasers.

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