Research On Space Laser Communication Based On Fiber Laser Phased Array

Recent years,the free space optical communication system usually uses 1.55?m semiconductor lasers,the launch power amplified by the erbium-doped fiber amplifier will be up to 5W,which limits the space transmission distance.Due to laser firing angle is not adjustable,we could rely on mechanical tracking system.As a new kind of coherent synthesis technology,the laser phased array can increase the energy of the output light by using the array structure,and control the phase of the synthesized light to realize the scanning of the transmitted beam angle,and improve the dynamic target capture speed.Laser phased array can be used in space laser communication system,which can greatly improve the performance of the system and realize the high-speed transmission and fast acquisition and tracking of ultra-long distance,which becomes the most promising laser communication technology.In this paper,the research progress of phased array and space optical communication is introduced firstly,then the basic principle of phased array and the related knowledge of communication are introduced.The communication system are mainly composed with the optical transmitter,optical receiver,optical antenna and the tracking and pointing system.The optical transmitter is composed of a seed source and a modulator,and the signal to be transmitted is loaded onto the optical carrier emitted by the seed source through the modulator and transmitted to the atmospheric channel through the optical antenna.The optical receiver consists of photodetector and signal processing equipment.The working principle of the modulator,detector and optical antenna in the system is studied.The basic 1.06?m space laser communication system is designed to realize high-speed communication.The modulation rate is 10Gb/s,the modulation mode is intensity modulation,and space transmission distance is 2m.The space laser communication system with fiber laser phased array seed source was studied,and the phased array space communication system was designed.The modulation rate was 53Mb/s,120Mb/s,155Mb/s and the transmission distance is 2m,the credibility of phased array laser communication is verified by experiments.The phased-array seed source and single-channel modulation experiment are compared,and the two methods are modulated at the seed source and modulated in the multiple branches of the phased array.Based on the obtained waveform and eye diagram,modulation at the seed source of the array is a suitable modulation method.The phased-array multicarrier modulation experiment is designed,and the intensity modulation is added simultaneously in the two branches of the phased-array multi-branch.After phase control,a clear spectrum spectrum is obtained at the receiving terminal,the minimum frequency difference is 0.08 MHz,and the maximum is20 MHz,showing that phased array can realize multi-carrier modulation,which proves the application of phased array in space communication.