Polarization states and Stokes vortices of dual Butterfly-Gauss vortex beams with uniform polarization in uniaxial crystals

Abstract

We propose dual Butterfly-Gauss vortex beams with uniform polarization, which are composed of two finite-energy Butterfly-Gauss beams with vortex cores. Based on the paraxial vector theory, the analytical propagation expressions of the proposed beams in uniaxial crystals orthogonal to the optical axis are derived and used to investigate the evolutions of autofocusing behavior, polarization states and Stokes vortices. The results show that the autofocusing behavior and its autofocusing length can be affected by topological charge, and the input uniform polarization is disordered into non-uniform polarization owing to anisotropic diffraction. The symmetry and rotation of polarization states are also found for the case of vortex. The Stokes parameters on the Poincaré sphere can be manipulated by adjusting the refractive index ratio, azimuthal angle and phase retardation angle. Their Stokes vortices, e.g. S12 vortices, present the behavior of merging, separation and reversal. The presented work may be useful for manipulating polarization dynamics of catastrophe optical field in uniaxial crystal and has potential values in polarization-sensitive detection.