Statistics of pulsed Laguerre-Gaussian beams in a turbulent atmosphere

摘要

Based on the numerical solution of the parabolic wave equation for the complex spectral amplitude of the wave field by using the splitting into physical factors method the fluctuations of energy density of the broadband pulsed optical radiation for various modes of the Laguerre-Gaussian beam under different turbulent conditions on the propagation path were studied. It has been shown that with the increase of optical turbulence the relative variance of energy density fluctuations of pulsed radiation of femtosecond duration becomes much lower than that of continuous-wave (cw) radiation and, in contrast, may become smaller than unity. Provided the pulse duration is short the energy density fluctuations tend to decrease as the order of the Laguerre-Gaussian beam mode rises. The level of residual spatial correlation of the strong energy density fluctuations of pulsed radiation exceeds the level of cw intensity correlation in all examined Laguerre-Gaussian beam modes and the typical two-scale structure of spatial correlation for the strong fluctuations of cw radiation in the case of pulsed radiation is less expressed.