Investigation On The Propagation Properties Of A Partially Coherent Laguerre-gaussian Beam In Turbulent Atmosphere

Laguerre-Gaussian beams (LGB) have important applications in laser physics, free-space optical communication, atom optics, electron acceleration and particles trapping asits special properties. In recent decades, numerous efforts have been paid to thepropagation properties of partially coherent beams in turbulent atmosphere, and it wasfound that partially coherent beams can overcome the negative influence induced byatmospheric turbulence, thus have potential applications in free-space opticalcommunication, laser radar and remote sensing. In this paper, our aim is to explore theevolution properties of the complex degree of coherence of partially coherent LGB inturbulent atmosphere with the help of the general propagation formula for such beams. Theevolution properties of such beam in free space and turbulent atmosphere have beenstudied in detail and comparatively.Firstly analytical expressions for the cross-spectral density and the complex degree ofcoherence of partially coherent LGB on propagation in turbulent atmosphere are derived, Itis found that the behavior of the complex degree of coherence of partially coherent LGBon propagation in turbulent atmosphere is closely related with the initial beam parametersand the structure constant of the turbulent atmosphere. Secondly, the differences betweenthe complex degree of coherence of partially coherent LGB on propagation in turbulentatmosphere and that in free space are analyzed. It is found that the behavior of the complexdegree of coherence of partially coherent LGB on propagation in turbulent atmosphere ismuch different from that in free space. The distribution of the modulus of the complexdegree of coherence of the partially coherent LGB finally becomes of Gaussian distributionat long propagation distance in turbulent atmosphere, and it becomes of Gaussiandistribution more slowly with the increase of the mode orders, beam width and wavelength.Our results show that a partially coherent LGB can reduce the negative influence of atmospheric turbulenceThe main results of present thesis will be useful in long-distance free-space opticalcommunications...