Research On Multi Terminal Access Method Based On Liquid Crystal Optical Phased Array Space Laser

Compared with traditional microwave communication,space laser communicat ion has higher transmission rate and stronger anti-jamming ability.These characteris tics make the space laser communication is the best solution to the high bit rate communication between satellites to ground and satellites to satellites in the future.However,at present,the research of space laser communication is thrown in the one point to one point communication mode.In the process of space laser communication and networking,in order to achieve a satellite with multiple satellites for data distribution,routing,switching and other networking functions,we need to study the physical beam access between a satellite terminal and a plurality of satellite terminals.Based on the theory of multi beam forming ability and multi beam forming of liquid crystal optical phased array,the multi user physical access method in the process of satellite laser communication acquisition and tracking are studied.The main research contents are as follows:1)In this paper,we analyze the basic theory of liquid crystal optical phased array,and the theory of liquid crystal elastic body,the distribution of the direction vector and the electrically controlled birefringence effect are studied.On this basis,combined with the theory of phased array radar.two kinds of multi beam generation structures based on liquid crystal optical phased array are proposed: Multi beam structure of adjacent sub arrays and multi beam structure of crossed subarray.And assuming that the four beams are generated,Simulation and analysis of the performance of these two kinds of structures are carried out.2)A multi terminal access model based on primary and secondary branches is designed.In this model,the linear relationship between the angle of arrival ?,the control angle ? and the beam angleq is deduced.The core of this method is to realize the access to multiple terminals by using multi beam generation and control ability of liquid crystal optical phased array.In this model,the LC-OPA in the sub branch is divided into two regions to process the newly accessed terminal,and the acquired position information data is shared to the main branch,the main branch is used to correct the information.Then,the multi terminal access method is verified by simulation,the position information of the beam in the far field and the diffraction efficiency and energy loss during the process are simulated to verify whether the scheme meets the requirements of the space laser communication terminal.The simulation results show that the diffraction efficiency of the access process is greater than 80%,energy loss less than 1dB.The simulation results show that the model is feasible in theory.3)Liquid crystal optical phased array multi terminal access experimental platform is set up.Firstly,the static liquid crystal characteristic curve of the liquid crystal optical phased array is tested.Then the principle verification test for two terminal access is carried out,using high resolution CCD to obtain the beam spot information in the far field,the experimental results are consistent with the simulation results of the multi terminal access method in this paper.the results show that the method is feasible and effective.