Study Of Dynamic Evolution Of Phase Singularities In The Beam Propagation

The phase singularities in the light field has become an important branch of modern optics,which shows attractive prospects in the optical communication,optical electronics,remote sensing,atomic capture,quantum information processing and other aspects.This paper is to study the dynamic evolution of the screw dislocation beams,the circular edge dislocation beams and the mixed circular edge-screw dislocations beams in the free space and the atmospheric turbulence.The major contents are as following:Based on the extended Huygens-Fresnel principle,the analytical expressions for the cross-spectral density function of partially coherent screw dislocation beams in free space and atmospheric turbulence are derived,and used to study the dynamic evolution of the higher-order coherent vortices and the higher-order optical vortices through the different value of topological charge.It is shown that both the partial coherence of optical field and disturbance of atmospheric turbulence induce higher-order coherent vortices to break down.Besides,the higher-order optical vortices are not broken down in free space,and the position of the higher-order optical vortices remains unchanged with the increase propagation distance.The analytical expressions for the cross-spectral density function of circular dislocation beams in free space and atmospheric turbulence are derived.The influence of atmospheric turbulence is discussed.It is shown that the number of circular edge dislocations on propagation equals that at the source plane when propagating through free space.n-circular edge dislocations vanish and transform to n pairs of optical vortices with the opposite topological charge when propagating through atmospheric turbulence,and the position of each pair of optical vortices is symmetric about the slanted axis y = x.All the optical vortices will annihilate as soon as the propagation distance becomes large enough.Besides,with the decrement of the intensity of atmospheric turbulence,the annihilation distance of the pairs of optical vortices will increase.The analytical expressions for the cross-spectral density function of mixed circular edge-screw dislocations beams in free space and atmospheric turbulenceare derived.The dynamic evolution of the mixed circular edge-screw dislocations is studied,and compare with the evolution of the screw dislocation and the circular edge dislocation in the space.It is shown that mixed circular edge-screw dislocations propagating in the free space,with the increment of the propagation distance,optical vortex and circular edge dislocation have always existed.Mixed circular edge-screw dislocations propagating in the atmospheric turbulence,with the increase of the propagation distance,the optical vortex with topological charge +m breaks down into m ones with topological charge +1,each circular edge dislocation evolves into a pair of optical vortices,when the transmission distance is far enough,each pair of optical vortices annihilates.Besides,the evolution of the optical vortex and circular edge dislocations of mixed circular edge-screw dislocations beams is similar to the evolution of the optical vortex of screw dislocations beams and the circular edge dislocations of circular edge dislocations beams.