Study On Propagation Dynamics Of Optical Vortex In Atmosphere

Optical vortex(OV)as a new kind of special light field that the phase distribution of the wave front is spiral and existence a singular point with zero strength,it is also carries orbital angular momentum.OVs have important practical applications in laser imaging,laser guidance,laser communication,remote sensing and received more and more attention from all countries of the world due to it is so many unique properties.The propagation dynamics of OVs in the atmosphere have become the research hot spot currently.The distribution properties of phase and intensity play an important role in driving the propagation dynamics of OVs.In this paper,based on rigorous scalar diffraction theory,propagation dynamics of off-axis symmetrical and asymmetrical OVs embedded in flat-topped beams have been explored numerically.Numerical results show that the single off-axis vortex moves in a straight line.The displacement of the single off-axis vortex becomes smaller,when either the order of flatness N and the beam size ?0 are increased or the off-axis displacement d is decreased.In addition,the phase singularities of high order vortex beams can be split after propagating a certain distance.It is also demonstrated that the movement of OVs are closely related with the spatial symmetrical or asymmetrical distribution of vortex singularities field.Multiple symmetrical and asymmetrical optical vortices embedded in flat-topped beams can interact and rotate.On the other hand,the spectral properties of the partially coherent vector anomalous vortex(AV)beam in the atmospheric turbulence are explored in detail by using thte unified theory of coherence and polarization.It is found from numerical results that the intensity distribution of the beam at the source plane has a hollow profile,with the increase of propagation distance,it converts to a Gaussian beam profile.It also found that the spectral degree of cross-polarization propagates through atmosphere tends to a constant value and the spectral coherence degree approaches to zero.The investment of this paper have many applications in optical micromanipulation and optical tweezers.