Study On Propagation Properties Of Electromagnetic Gaussian Schell-model Beam Propagating In Atmospheric Turbulence

Because of the turbulence in the atmosphere,when the laser beams propagation in the atmospheric turbulence will produce a series of turbulent effects,which seriously affects the beam quality and restricts its applications in radar,remote sensing and communication technology,and so on.Therefore,it is very important to study the propagation properties of laser beams in atmospheric turbulence.Recently,the research results show that the partially coherent beams is less affected by turbulence than fully coherent beams,while the electromagnetic Gaussian Schell-model(EGSM)is a typical partially coherent beam model.Thus,it is of practical significance to study its propagation in atmospheric turbulence.Based on the extended Huygens-Fresnel integral and the second-order moments of the Wigner distribution function,the propagation properties of EGSM beam in inhomogeneous atmospheric turbulence,the propagation of EGSM array beam in Tatarskii turbulence and non-Kolmogorov turbulence,and the propagation characteristics of EGSM vortex beam in non-Kolmogorov turbulence are studied.The main research contents and results are as follows:1?The analytical formulas for the root-mean-square(rms)angular width,rms spatial width,M2-factor of EGSM beam in turbulence are derived.Meanwhile,the effects of turbulence parameters(the inner scale of turbulence,the outer scale of turbulence,zenith angle)and beam parameters(beam width,coherence length,and wavelength)on the relative rms spatial width,rms angular width,M2-factor are numerically simulated.The results show that as the zenith angle is equal to ?/6,the saturated propagation distances of the relative rms angular width,the relative rms spatial width,and the relative M2-factor are about 0.3 km,3 km and 20 km,respectively.And it also can be found that the relative M2-factor becoles small when the initial degree of polarization closes to 0.2?The analytical formula of M2 factor for electromagnetic Gaussian Schell-model array(EGSMA)beam propagating in Tatarskii turbulence and non-Kolmogorov turbulence is derived.At the same time,the beam wander of Hermite Gaussian correlated Schell model(HGCSM)beam and EGSMA beam in non-Kolmogorov turbulence are compared and analyzed.The results show that the smaller ?0x is,the better beam quality is when the EGSMA beam propagates in Tatarskii turbulence and non-Kolmogorov turbulence.Otherwise,with the increase of beam number N,the beam is less affected by turbulence,which means the beam quality is higher.By comparing the propagation of HGSM beam and EGSM beam in non-Kolmogorov turbulence,it is found that the relative beam wander increases with the increase of the generalized structure parameter,which indicates that the beam wander is obviously affected by turbulence.3?The expressions for the M2-factor and beam wander of EGSM vortex beam in non-Kolmogorov atmospheric turbulence are derived.The effects of beam width,generalized exponential parameters,coherent length and the generalized structure parameter on the relative M2 factor and relative beam wander are analyzed numerically.The results show that the relative beam wander increases rapidly as the propagation distance z<2km,and when the propagation distance increases,its increases slowly and finally tends to stabilize gradually,and when the propagation distance is greater than 2km5 the M2-factor increases rapidly.The sensitivity of beam propagation to beam parameters and turbulence parameters is higher than beam wander.