Statistics of pulsed Laguerre-Gaussian beams in the turbulent atmosphere
V.A. Banakh, L.O. Gerasimova, A.V. Falits
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
Keywords: лагерр-гауссов пучок, импульсное излучение, турбулентная атмосфера, параболическое волновое уравнение, метод расщепления по физическим факторам, комплексная спектральная амплитуда, Laguerre-Gaussian beam, short pulse, turbulent atmosphere, parabolic wave equation, method of splitting into physical factors, complex spectral amplitude
Abstract
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 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 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 Laguerre-Gaussian beam mode rises. The level of residual spatial correlation of strong energy density fluctuations of pulsed radiation exceeds the level of continuous-wave intensity correlation in all examined Laguerre-Gaussian beam modes and the typical two-scale structure of spatial correlation for strong fluctuations of continuous-wave radiation in the case of pulsed radiation is less expressed.
|
