Adaptive Dual-mirror Coupling Technology From Satellite Optical Communication Space Light To Single-mode Fiber

Satellite laser communication is a communication method that uses light-wave satellite Internet electromagnetic waves instead of traditional microwaves.It has the advantages of large communication capacity,high security,concentrated energy,small antenna size,and low transmission power consumption.In satellite-to-earth communication,laser transmission in the atmosphere is affected by atmospheric interference,and distortion and attenuation are more serious.However,applying it to vacuum inter-satellite communication can give full play to its advantages.In recent years,the use of communication satellite networking,interconnection with ground base stations,and the construction of a world-integrated Internet system have become key competitive projects in countries around the world.Among them,the laser communication terminal mounted on the satellite is the key research direction of the satellite communication load in the future.Because of its extremely small communication field of view,satellite laser communication must require terminal equipment to be equipped with a high-precision aiming,acquisition and tracking system to realize the construction and maintenance of communication links over thousands or even tens of thousands of kilometers.Then,the received space light is led into the optical fiber,demodulated,and the communication function is realized.Among them,the most critical part is the coupling process of space light to optical fiber.Compared with multimode fiber,single-mode fiber has the advantages of high coupling efficiency and good filtering performance during coupling.It is currently commonly used coupling fiber.However,due to the small diameter of the end face of the single-mode fiber,to achieve higher coupling efficiency,high alignment accuracy of the beam and the fiber is required.This is one of the key technologies of satellite laser communication.In recent years,the use of nutating coupling technology to achieve high coupling efficiency from space light to single-mode fiber has attracted wide attention from researchers.The core idea is to use a fast mirror to provide conical scanning,determine the relative deviation of the beam and the fiber based on energy feedback,and correct it.This structure has the advantages of small size,simple structure and high accuracy,and has great application value in the field of satellite laser communication.Based on the above advantages,this paper studies the application of nutating coupling technology in satellite laser communication,mainly including the following work:First,analyze the working principle of fine sighting mirror in traditional PAT and the working principle of nutating mirror of nutating coupling system.It is believed that the nutating mirror and the traditional PAT structured precision scope can form a double mirror system,which has higher tracking accuracy and stronger stability than the traditional single precision scope system.The mathematical model of the light beam propagating in the dual mirror system is established,and the adaptability principle of the dual mirror system working in the space and time domains is analyzed.Secondly,in-depth study of the key parameters of the nutation coupling system work,through simulation analysis and control experiments,get two working parameters of nutation radius and iteration step and nutation coupling system work fast,stable,accurate three A qualitative relationship.The study found that setting fixed operating parameters is difficult to meet the actual needs of satellite laser communications.An adaptive nutating coupling system with adjustable working parameters needs to be designed.Finally,simulation experiments verify the reliability of the adaptive system,and put forward suggestions for improvement.The application of nutating coupling technology to satellite laser communication can promote the development of miniaturization of terminals,and has great application value in the future.The research results of this paper are of great significance to the engineering practice of nutating coupling technology in satellite laser communication.