Research On Key Technologies Of Active Adaptive Optics For Atmospheric Laser Communication System

At present,the main problem facing atmospheric laser communication technology is the influence of turbulence on the optical signal in the atmospheric channel.Adaptive optics technology is currently considered to be the most important method to address the effects of atmospheric turbulence.This paper mainly studies the influence mechanism of atmospheric turbulence on laser communication system and the improvement effect of adaptive optics on communication system.The main tasks are as follows:Firstly,the atmospheric turbulence effect was introduced from three aspects: basic characteristics,models and characteristic parameters,the formula for the coupling efficiency of laser communication systems containing adaptive optical system parameters was summarized,and the relationship between coupling efficiency,Zernike fitting order,and adaptive optical correction bandwidth parameter f G/f3 d B under different turbulence intensities is analyzed.Secondly,the composition of the adaptive optical system for atmospheric laser communication is briefly described,the working principle of the adaptive optical system is studied from the aspects of the Zernike polynomial expression of the wavefront,the working principle of the S-H sensor and deformable mirror,the wavefront correction algorithm,and the selection of the performance index of the adaptive optical system is analyzed.Thirdly,this paper combines two adaptive optical wavefront correction algorithms and designs a combined correction algorithm,the rationality of the algorithm is verified by numerical simulation methods,and the performance of the algorithm is further analyzed under two conditions of different turbulence intensity and fitting accuracy,the results prove that the combined correction algorithm has better correction effect and faster correction speed than the two algorithms alone.Finally,a wavefront-free adaptive optics technology based on binary light intensity modulation is studied,by the process of phase unwrapping and smoothing of the reconstructed wavefront based on the Walsh function,it is verified that this technique can meet the higher accuracy of wavefront reconstruction,according to the analysis of simulation results of wavefront samples corrected under different turbulence intensities,it is proved that this technology has high adaptability to strong turbulence and has the potential for application of atmospheric laser communication systems under strong turbulence.