Research Of High Efficiency Fiber Coupling Technology In Atmospheric Laser Communication System

The atmospheric laser communication has been developing rapidly due to its advantages,such as large capacity of information,high transformation rates,strong anti-jamming capability and high anti-interception ability.The mature fiber optic devices apply to the atmospheric laser communication has great advantage.For this reason the efficient technology of coupling space light into single-mode fiber is the key technique in the atmospheric laser communication.This paper studies the coupling efficiency of spatial light into fiber with alignment error,random angular jitters and atmospheric turbulence.In order to reduce the difficulty of spatial light into single-mode fiber,improve the coupling efficiency,this paper adopts single-mode multi-core fiber and few-mode-fiber to receive signal light respectively,establishes the coupling efficiency mode of the spatial light into single-mode multi-core fiber and the spatial light into few-mode-fiber,The simulation results show that adopting single-mode multi-core fiber and few-mode-fiber to receive signal light has stronger ability to improve coupling efficiency and suppress interferences of the platform jitter and the aiming error.Experimental setup of space light into single-mode fiber is established.The effect of alignment error and random angular jitters on the coupling efficiency of space light into single-mode fiber and the effect of angular deviation on two-mode fiber is verified.When the deviation of angle is 180?rad,the coupling efficiency of two-mode fiber is improve 13.31% than the single-mode fiber.Experimental results are coincident with the theoretical analysis.In order to reduce the effect of atmospheric turbulence and the platform jitter on communication system,this paper studies adaptive optics and a coupling system based on laser nutation.Explaining the basic principles of adaptive optics.Deducing the algorithm of miss distance,analyzing the effect of the nutation amplitude and the sampling numbers on the miss distance algorithm precision.The accuracy of miss distance is about 0.01?m when the number of sampling points is 240 by simulation.The content of the research provides theoretical foundation for the design of the atmospheric laser communication.