The Research On Wavefront Sensor-less Adaptive Optical Compensation Technology Of Orbital Angular Momentum Beam

Optical Vortices(OV)is a beam that carries orbit angular momentum(OAM)which can effectively improve the utilization of the communication system.However,the phase distortion causing by atmospheric turbulence will affect the performance of the communication system in the wireless optical communication system using optical vortices.Adaptive optics are used to solve this problem.But it still remains some problems even though the system complexity have being reduced by the wavefront sensorless adaptive optics system which utilizes optimization algorithms to find the correct phase.In this paper,the optimization algorithms using in adaptive optics are being explored and some improved algorithm proposed.The main work and results are as follows:Firstly,we designed an improved SPGD algorithm that uses gain coefficient in a stepwise way.The simulation results show that the algorithm can effectively expands the range of gain coefficient andimprove the stability of SPGD algorithm.Secondly,a new version of SPGD called MZ-SPGD is proposed which introduces low frequency disturbance and high frequency disturbance simultaneously and the stability and effectiveness is verified by simulation.Thirdly,this paper proposes a new adaptive optical compensation algorithm that use BP neural network to predict initial value of optimization algorithm.The adaptive optics system structure is designed for this improved algorithm and the algorithm flow is declared.And the accuracy of the initial value of BP neural network prediction and the stability of repair under different atmospheric turbulence are verified through simulation.