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Atmospheric and Oceanic Optics

2015 year, number 4

Ring dislocation of the degree of coherence of a vortex Bessel beam in turbulent atmosphere

I.P. Lukin
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
Keywords: Bessel beam, vortex beam, optical radiation, atmospheric turbulence, coherence, ring dislocation

Abstract

The behavior of the degree of coherence of a coherent vortex Bessel optical beam propagating in a turbulent randomly inhomogeneous medium is theoretically considered. The influence of an optical vortex on the degree of coherence of the Bessel beam in a randomly inhomogeneous medium is studied. The analysis is based on the solution of the equation for the second-order mutual coherence function of optical beam field. On the basis of this solution, the behavior of the module of the second-order mutual coherence function (a degree of coherence), the vortex Bessel beam field is investigated. It is shown that at low levels of fluctuations in the turbulent atmosphere, in the central part of a two-dimensional field of the degree of coherence of vortex Bessel beams, the ring dislocation is formed; the number of rings is equal to value of a topological charge of an optical beam. The structure of a ring dislocation of the degree of coherence of vortex Bessel optical beams in turbulent atmosphere is studied in detail. For this purpose, two characteristics of the ring dislocation are introduced: the spatial coordinate and width of a ring. The influence of parameters of an optical beam (a cross-section wave number and a topological charge) and atmospheric turbulence (a coherence radius of a plane optical wave) on these characteristics of the ring dislocation of the degree of coherence of a vortex Bessel optical beam is considered.