Atmospheric Turbulence On The Spatial Coherence Of Partially Coherent Light Impact Study

In optical communication, the intensity scintillation, beam wander, beam spreading, angle-of-arrival fluctuation and phase fluctuation caused by atmospheric turbulence effects have led to high BER and channel capacity, as well as poor the reliability and stability of communication. Therefore, studies on how to make mitigation technologies of turbulence effects to be the key technology of atmosphere laser communication has been of great academic and practical importance for it would directly determine the feasibility of communication system. Meanwhile, since the technology of partially coherent beam was better than full-coherent beam technology, it occupied a pivotal status in mitigation technologies of turbulence effects.This thesis aims at discussing the issues mentioned above, it mainly studied a typical partially coherent beam-Gaussian Schell-model(GSM) beam. At the base of brief introduction of turbulence’s mechanism, it combined GSMH-G beam with Hermite-Gaussian(H-G) beams by means of incoherent stack.In the same time, by extended Huygens-Fresnel principle, the transmission formula and cross. spectral density function of GSMH-G beams after passing atmospheric turbulence were also derived, and the turbulence adopted Von Karman spectral, thus, the expression of spectral degree of coherence after beams passed atmospheric turbulence. What’s more, it adopted stilulation by using Matlab software to study the spatial coherence of GSMH-G, and got the conclusion in accordance with practice. In addition, it also studied a special partially coherent beam such as partially coherent vortex-Gaussian beams. Studies showed that the spatial coherence was mainly affected by the coherence of light source, the number of topological charges and the transmission distance, when partially coherent vortex-Gaussian beams spreaded through the atmospheric turbulence. The distance of transmission was farther, the spatial coherence of beam was better. The number of topological charges were more, the spatial coherence of beam was better. In a certain transmission distance, the coherence of light source was better, the spatial coherence of beam was worse. In addition, there were coherent vortexes which spectral degree of coherence was zero after the partially coherent vortex beams getting through atmospheric turbulence transmission.