Research On Key Technologies Of Spatial Compensation For Transatmospheric Laser Communication

Free-space Optical Communication(FSOC)has the advantages of high transmission rate and good communication confidentiality.Therefore,it keeps high research value and wide engineering application range.However,the existence of atmospheric turbulence as channel noise in the atmosphere communication channel disturbes the reliability of the communication link.Adaptive Optics(AO),as an effective means to suppress atmospheric turbulence effect,is often applied to optical communication receivers and is an important subject branch under FSOC system.In this paper,we focus on the key technology of spatial compensation for trans-atmospheric laser communication and investigate AO.The main research contents are as follows:(1)In this paper,we researched the hysteresis modeling of Fast Steering Mirror(FSM).Firstly,since the FSM uses piezoelectric ceramic material which brings hysteresis and creep.The features are commonly modeled separately.Secondly,since the hysteresis and creep are coupled in the output,the training set for modeling the hysteresis contains the noise of creep.Because FSM works at high frequency in AO,and the hysteresis is more significant than the creep at high frequency.As a result,this paper proposed a frequency reconstruction method to improve the hysteresis model accuracy by preprocessing the training set.The experimental results showed that the frequency point reconstruction can improve the modeling accuracy by 18.7%,and the coefficients satisfy the bounded input and bounded output,which demonstrated the improvement of the modeling effect by the frequency reconstruction.(2)Firstly,the wavefront correction algorithm based on the nonlinear response model is researched in this paper.Because of the nonlinear response model for both FSM and DM,the wavefront correction algorithm based on the nonlinear response model is extended from the hardware scenario of single deformable mirror(DM)to FSM and DM cascade scenario.Subsequently,the effectiveness of the algorithm is verified by simulation.Meanwhile,a comparative study of the response capability of Micromachined Membrane Deformable Mirror(MMDM)and Piezoelectric Deformable Mirror(PDM)is carried out.This paper demonstrated the advantages of PDM compared with MMDM by analyzing the offsets distribution,Zernike characterizing capability and turbulence compensating capability.In summary,this paper is a reference for the construction and driving of AO systems.