阅读说明：本技术 一种用于空间激光通信的电光章动耦合系统及方法 (Electro-optical nutation coupling system and method for space laser communication ) 是由 赵�卓 刘向南 向程勇 廖为桂 李晓亮 谌明 于勇 李凉海 于 2019-08-28 设计创作，主要内容包括：一种用于空间激光通信的电光章动耦合系统及方法,属于激光通信领域。本发明包括四分之一波片、快速反射镜、电光偏转器、耦合透镜、单模光纤、光开关、非相干接收模块、相干接收模块、通信及角误差解算模块、电光偏转器驱动模块、快速反射镜驱动模块。本发明基于电光偏转效应,采用非机械式的电光偏转器件,通过控制电光偏转器实现激光光束的二维扫描和章动耦合,在通信信息解调的同时完成激光信号的跟踪角误差量的提取和补偿量的计算,并控制电光偏转器和快速反射镜进行精跟踪补偿,实现激光信号的高精度跟踪和空间光到单模光纤的稳定高效耦合。本发明可兼容非相干和相干通信体制下的跟踪角误差解算与补偿。(An electro-optical nutation coupling system and method for space laser communication belong to the field of laser communication. The device comprises a quarter-wave plate, a fast reflector, an electro-optic deflector, a coupling lens, a single-mode fiber, an optical switch, an incoherent receiving module, a coherent receiving module, a communication and angle error resolving module, an electro-optic deflector driving module and a fast reflector driving module. The invention is based on the electro-optic deflection effect, adopts a non-mechanical electro-optic deflection device, realizes the two-dimensional scanning and nutation coupling of laser beams by controlling the electro-optic deflector, completes the extraction of the tracking angle error amount of laser signals and the calculation of compensation amount while demodulating communication information, and controls the electro-optic deflector and a quick reflector to carry out fine tracking compensation, thereby realizing the high-precision tracking of the laser signals and the stable and efficient coupling of space light to a single-mode optical fiber. The invention can be compatible with the tracking angle error calculation and compensation under the incoherent and coherent communication systems.)

1. An electro-optical nutation coupling system for spatial laser communication, characterized by: the device comprises a quarter-wave plate (1), a fast reflector (2), an electro-optic deflector (3), a coupling lens (4), a single-mode fiber (5), an optical switch (6), an incoherent receiving module (7), a coherent receiving module (8), a communication and angle error resolving module (9), an electro-optic deflector driving module (10) and a fast reflector driving module (11);

parallel light beams are transmitted by the quarter-wave plate (1), then are reflected by the quick reflector (2) to enter the electro-optic deflector (3), and then the light beams transmitted by the electro-optic deflector (3) are focused on the fiber end face of the single-mode fiber (5) by the coupling lens (4);

the single-mode optical fiber (5) converts the light beam into an optical signal, is connected with the optical switch (6) through an output port of the single-mode optical fiber, and transmits the optical signal to the optical switch (6); the first output end and the second output end of the optical switch (6) are respectively connected with the incoherent receiving module (7) and the coherent receiving module (8), and the optical signal is switched and output to the incoherent receiving module (7) or the coherent receiving module (8) according to the control signal selection of the upper computer;

the input end of the communication and angle error resolving module (9) is respectively connected with the output end of the incoherent receiving module (7) and the output end of the coherent receiving module (8), generates a communication electric signal and sends the communication electric signal to the communication and angle error resolving module (9); the communication and angle error calculation module (9) receives the communication electric signal, performs signal demodulation and angle error calculation, and respectively sends the calculated first angle error information and second angle error information to the electro-optical deflector driving module (10) and the fast reflector driving module (11);

the input end of the electro-optical deflector driving module (10) is connected with the first output end of the communication and angle error resolving module (9), the input end of the rapid reflector driving module (11) is connected with the second output end of the communication and angle error resolving module (9), the electro-optical deflector driving module (10) receives first angle error information, the light beam deflection angle output by the electro-optical deflector (3) is controlled, the rapid reflector driving module (11) receives second angle error information, the vibration direction and amplitude of the rapid reflector (2) are controlled, and therefore the light beam coupling efficiency of the optical fiber end face entering the single-mode optical fiber (5) is maximum.

2. An electro-optical nutating coupling system for spatial laser communication according to claim 1, wherein: the quarter-wave plate (1) is a zero-order wave plate and is used for enabling the polarization state of the transmitted light beam to be consistent with the polarization state of the input light beam required by the electro-optical deflector (3).

3. An electro-optical nutating coupling system for spatial laser communication according to claim 2, wherein: the fast reflector (2) is a piezoelectric ceramic fast reflector.

4. An electro-optical nutating coupling system for spatial laser communication according to claim 3, wherein: the electro-optical deflector (3) is an electro-optical crystal deflector.

5. An electro-optical nutating coupling system for spatial laser communication according to claim 2, wherein: the coupling lens (4) is a glass lens and is used for focusing the light beams transmitted by the electro-optical deflector (3) to the fiber end face of the single-mode fiber (5).

6. An electro-optical nutating coupling system for spatial laser communication according to claim 1, wherein: the single-mode optical fiber (5) is a single-mode polarization-maintaining optical fiber.

7. An electro-optical nutating coupling system for spatial laser communication according to claim 1, wherein: the optical switch (6) is an MEMS polarization maintaining switch or a mechanical polarization maintaining switch and is used for controlling the switching of optical signals on two optical paths.

8. An electro-optical nutating coupling system for spatial laser communication according to claim 1, wherein: the communication electric signal is an OOK communication system, a PPM communication system, a BPSK communication system or a QPSK communication system.

9. An electro-optical nutating coupling system for spatial laser communication according to claim 1, wherein: the first angular error information has a size of [1,5) μ rad, and the second angular error information has a size of [5,100) μ rad.

10. An electro-optical nutation coupling system implementation method for space laser communication based on any one of claims 1 to 9, characterized by comprising the following steps:

parallel light beams are transmitted through the quarter-wave plate (1), are reflected through the quick reflector (2) and enter the electro-optic deflector (3), and then the light beams transmitted through the electro-optic deflector (3) are focused on the fiber end face of the single-mode fiber (5) through the coupling lens (4);

the single-mode optical fiber (5) transmits an optical signal to the optical switch (6), and the optical switch (6) switches and outputs the optical signal to the incoherent receiving module (7) or the coherent receiving module (8) according to the control signal of the upper computer;

the incoherent receiving module (7) or the coherent receiving module (8) receives the optical signal, converts the optical signal into a communication electric signal and outputs the communication electric signal to the communication and angle error resolving module (9);

the communication and angle error calculation module (9) carries out signal demodulation and angle error calculation on the communication electric signal, and respectively sends the calculated first angle error information and second angle error information to the electro-optical deflector driving module (10) and the fast reflector driving module (11);

the electro-optical deflector driving module (10) receives the first angle error information, controls a light beam deflection angle output by the electro-optical deflector (3), and the quick reflector driving module (11) receives the second angle error information, controls the vibration direction and amplitude of the quick reflector (2), so that the light beam entering the end face of the single-mode fiber (5) has the maximum coupling efficiency.

Technical Field

The invention relates to an electro-optic nutation coupling system and method for space laser communication, and belongs to the field of laser communication.

Background

Compared with the traditional microwave communication, the space laser communication has the characteristics of high transmission rate, strong anti-interference capability, small terminal volume, low power consumption, light weight and the like, so that the space laser communication becomes one of the current high-speed inter-satellite and inter-satellite-ground communication technology development directions with the most potential. With the increasing demand of space laser communication networking application, a space laser communication terminal needs to be compatible with a coherent communication system and an incoherent communication system. Based on the advantages of the optical fiber photoelectric detection device, at the receiving end of the space laser communication link, the space beam received by the optical system needs to be coupled into the single-mode optical fiber first, and then high-speed detection is carried out to realize high-speed photoelectric conversion. With the increasing application of optical fiber communication technology in space laser communication systems, the realization of efficient and stable coupling of space light to single-mode optical fiber is a precondition for ensuring the performance of laser communication systems. In addition, in practical application, the space laser communication system is influenced by factors such as vibration, thermal effect and atmospheric turbulence of a satellite and other carrying platforms, so that dynamic and efficient coupling of space light beams to single-mode optical fibers is very difficult.

At present, the common coupling schemes for spatial light to a single-mode fiber include mechanical fiber coupling, fast mirror coupling, microlens array coupling, and the like. However, the mechanical fiber coupling scheme has poor mechanical stability and low coupling bandwidth; the coupling efficiency of the quick reflector coupling scheme is high, but the mechanical coupling scheme still has the defects of low bandwidth, complex control system, short service life and the like; the microlens array coupling scheme is complicated in structure and requires an additional optical system; the coupling scheme of the liquid crystal spatial light modulator is limited by the characteristics of liquid crystal materials, and has the problems of low response speed, low diffraction efficiency and the like, and the spatial environment adaptability is poor.

Chinese patent publication No. CN104811244A discloses a coupling system from space light to single-mode fiber based on laser nutation, which realizes laser nutation coupling under incoherent detection system by utilizing nutation of a fast reflector. Chinese patent publication No. CN109560878A discloses an adaptive coupling system from spatial light to single-mode fiber based on coherent detection, which utilizes fiber nutation to realize laser nutation coupling under a coherent detection system. Although the above two technical schemes all realize nutation coupling of space light to single-mode fiber in space laser communication, the problems of high bandwidth, long service life, compatibility with an incoherent communication system and a coherent communication system, simultaneous application to satellite-borne, airborne and ground laser communication terminals and the like are not thoroughly solved. Although the chinese patent with publication No. CN104811244A realizes laser nutation coupling under an incoherent detection system by utilizing nutation of the fast reflector, the vibration frequency of the fast reflector is 10kHz, but the effective bandwidth of the fast reflector is less than 1kHz, usually about 500Hz, and compared with the vibration frequency of 250Hz of a satellite platform, the ability of the fast reflector to suppress the vibration of the satellite platform is very poor, and the fast reflector is difficult to be applied to a satellite-borne laser communication terminal; meanwhile, the vibration of the nutation fast reflector belongs to mechanical vibration, and the service life of the nutation fast reflector is related to the vibration frequency and the vibration frequency, so that the service life of the fast reflector is short, the nutation fast reflector is suitable for a ground laser communication receiving system at the moment, and is only used for an incoherent detection system, the system compatibility is poor, and the service life is short. Although the chinese patent with publication number CN109560878A realizes laser nutation coupling under coherent detection system by using fiber nutation, the piezoelectric ceramic tube clamping single mode fiber by driving center nutates, and this nutation mode also has mechanical motion and short service life; meanwhile, the technical scheme is only limited to support a coherent communication system, and the compatibility of the system is poor. Due to the introduction of the mechanical motion of the optical fiber, the system has high complexity and poor stability.

Disclosure of Invention

The technical problem solved by the invention is as follows: the system and the method for efficiently coupling the space light to the single-mode optical fiber have the advantages of simple structure, low power consumption, high bandwidth, long service life and good space environment adaptability, and are compatible with an incoherent communication system and a coherent communication system.

The technical solution of the invention is as follows: an electro-optic nutation coupling system for space laser communication comprises a quarter-wave plate, a fast reflector, an electro-optic deflector, a coupling lens, a single-mode fiber, an optical switch, an incoherent receiving module, a coherent receiving module, a communication and angle error resolving module, an electro-optic deflector driving module and a fast reflector driving module;

after being transmitted by the quarter-wave plate, the parallel light beams enter the electro-optic deflector through reflection of the quick reflector, and then the light beams transmitted by the electro-optic deflector are focused on the fiber end face of the single-mode fiber by the coupling lens;

the single mode fiber converts the light beam into an optical signal, is connected with the optical switch through an output port of the single mode fiber and transmits the optical signal to the optical switch; the first output end and the second output end of the optical switch are respectively connected with the incoherent receiving module and the coherent receiving module, and the optical signal is switched and output to the incoherent receiving module or the coherent receiving module according to the selection of the control signal of the upper computer;

the input end of the communication and angle error resolving module is respectively connected with the output end of the incoherent receiving module and the output end of the coherent receiving module, generates a communication electric signal and sends the communication electric signal to the communication and angle error resolving module; the communication and angle error calculation module receives the communication electric signal, performs signal demodulation and angle error calculation, and respectively sends the calculated first angle error information and second angle error information to the electro-optical deflector driving module and the fast reflector driving module;

the input end of the electro-optical deflector driving module is connected with the first output end of the communication and angle error calculation module, the input end of the quick reflector driving module is connected with the second output end of the communication and angle error calculation module, the electro-optical deflector driving module receives first angle error information and controls the light beam deflection angle output by the electro-optical deflector, the quick reflector driving module receives second angle error information and controls the vibration direction and amplitude of the quick reflector, and therefore the light beam coupling efficiency of the optical fiber end face entering the single-mode optical fiber is the largest.

Further, the quarter-wave plate is a zero-order wave plate, and is used for enabling the polarization state of the transmitted light beam to be consistent with the polarization state of the input light beam required by the electro-optical deflector.

Furthermore, the fast reflector is a piezoelectric ceramic fast reflector.

Further, the electro-optical deflector is an electro-optical crystal deflector.

Further, the coupling lens is a glass lens and is used for focusing the light beam transmitted by the electro-optical deflector to the fiber end face of the single-mode fiber.

Further, the single-mode fiber is a single-mode polarization maintaining fiber.

Further, the optical switch is an MEMS polarization maintaining switch or a mechanical polarization maintaining switch, and is used to control the switching of the optical signal on the two optical paths.

Further, the communication electrical signal is an OOK communication system, a PPM communication system, a BPSK communication system, or a QPSK communication system.

Further, the size of the first angle error information is [1,5) μ rad, and the size of the second angle error information is [5,100) μ rad.

An electro-optical nutation coupling system implementation method for space laser communication based on the electro-optical nutation coupling system comprises the following steps:

parallel light beams are transmitted through the quarter-wave plate, reflected by the quick reflector and enter the electro-optic deflector, and then the light beams transmitted by the electro-optic deflector are focused on the fiber end face of the single-mode fiber by the coupling lens;

the single mode fiber transmits the optical signal to the optical switch, and the optical switch switches and outputs the optical signal to the incoherent receiving module or the coherent receiving module according to the control signal selection of the upper computer;

the incoherent receiving module or the coherent receiving module receives the optical signal, converts the optical signal into a communication electric signal and outputs the communication electric signal to the communication and angle error resolving module;

the communication and angle error calculation module carries out signal demodulation and angle error calculation on the communication electric signal and respectively sends the calculated first angle error information and second angle error information to the electro-optical deflector driving module and the quick reflector driving module;

the electro-optical deflector driving module receives the first angle error information and controls the deflection angle of the light beam output by the electro-optical deflector, and the quick reflector driving module receives the second angle error information and controls the vibration direction and amplitude of the quick reflector, so that the coupling efficiency of the light beam entering the end face of the single-mode optical fiber is the maximum.

Compared with the prior art, the invention has the advantages that:

(1) the system adopts an electro-optic nutation coupling scheme, realizes two-dimensional deflection and nutation of light beams by utilizing an electro-optic effect, has no mechanical motion, has the characteristics of long service life, large bandwidth and strong capability of inhibiting platform vibration, can be widely applied to satellite-borne, airborne and ground laser communication systems, and has good space environment adaptability;

(2) the system realizes the switching control of the light path by using the optical switch, and is compatible with the light beam nutation coupling under an incoherent communication system and a coherent communication system;

(3) the system realizes the integrated design of the incoherent communication module and the coherent communication module while adopting the electro-optical nutation coupling, and effectively reduces the weight, the volume, the power consumption and the overall complexity of the system.

Drawings

FIG. 1 is a schematic block diagram of the system of the present invention.

Detailed Description

The present invention is further illustrated in detail below with reference to the drawings and examples, but the scope of the present invention should not be limited thereto.

As shown in fig. 1, the system of the invention includes a quarter-wave plate 1, a fast reflector 2, an electro-optic deflector 3, a coupling lens 4, a single-mode fiber 5, an optical switch 6, an incoherent receiving module 7, a coherent receiving module 8, a communication and angle error resolving module 9, an electro-optic deflector driving module 10, and a fast reflector driving module 11. After being transmitted by the quarter-wave plate 1, the parallel light beams are reflected by the quick reflector 2 to enter the electro-optic deflector 3, and then the light beams transmitted by the electro-optic deflector 3 are focused on the fiber end face of the single-mode fiber 5 by the coupling lens 4; the single-mode optical fiber 5 converts the light beam into an optical signal, is connected with the optical switch 6 through an output port thereof, and transmits the optical signal to the optical switch 6; the first output end and the second output end of the optical switch 6 are respectively connected with the incoherent receiving module 7 and the coherent receiving module 8, and the optical signal is switched and output to the incoherent receiving module 7 or the coherent receiving module 8 according to the selection of the control signal of the upper computer; the input end of the communication and angle error resolving module 9 is respectively connected with the output end of the incoherent receiving module 7 and the output end of the coherent receiving module 8, generates a communication electric signal and sends the communication electric signal to the communication and angle error resolving module 9; the communication and angle error calculation module 9 receives the communication electric signal, performs signal demodulation and angle error calculation, and respectively sends the calculated first angle error information and second angle error information to the electro-optical deflector driving module 10 and the fast reflector driving module 11; the input end of the electro-optical deflector driving module 10 is connected with the first output end of the communication and angle error calculation module 9, the input end of the fast reflector driving module 11 is connected with the second output end of the communication and angle error calculation module 9, the electro-optical deflector driving module 10 receives first angle error information, the deflection angle of a light beam output by the electro-optical deflector 3 is controlled, the fast reflector driving module 11 receives second angle error information, the vibration direction and amplitude of the fast reflector 2 are controlled, and therefore the light beam coupling efficiency of the optical fiber end face entering the single-mode optical fiber 5 is the largest. The first angular error information has a size of [1,5) μ rad, and the second angular error information has a size of [5,100) μ rad.

An electro-optical nutation coupling method for spatial laser communication, comprising the steps of:

parallel light beams are transmitted through the quarter-wave plate 1, reflected through the quick reflector 2 and enter the electro-optic deflector 3, and then the light beams transmitted through the electro-optic deflector 3 are focused on the fiber end face of the single-mode fiber 5 through the coupling lens 4;

the single mode fiber 5 transmits the optical signal to the optical switch 6, and the optical switch 6 switches and outputs the optical signal to the incoherent receiving module 7 or the coherent receiving module 8 according to the control signal selection of the upper computer;

the incoherent receiving module 7 or the coherent receiving module 8 receives the optical signal, converts the optical signal into a communication electric signal, and outputs the communication electric signal to the communication and angle error resolving module 9;

the communication and angle error calculation module 9 performs signal demodulation and angle error calculation on the communication electric signal, and respectively sends the calculated first angle error information and second angle error information to the electro-optical deflector driving module 10 and the fast reflector driving module 11;

the electro-optical deflector driving module 10 receives the first angle error information to control the beam deflection angle output by the electro-optical deflector 3, and the fast reflector driving module 11 receives the second angle error information to control the vibration direction and amplitude of the fast reflector 2, so that the coupling efficiency of the beam entering the optical fiber end face of the single-mode optical fiber 5 is the maximum.