Non-canonical propagation of high-order elliptic vortex beams in a uniaxially anisotropic medium

Abstract

We have analysed propagation of nonparaxial and paraxial beams perpendicular to the optic axis in a uniaxially anisotropic medium (unbounded optically uniaxial crystal). We have presented the paraxial solutions in the form of generalised Hermite-Gaussian beams propagating perpendicular to the optic axis in a uniaxially anisotropic medium. We have also constructed the generalised Laguerre-Gaussian beams at the z=0 plane and analysed their evolution in a homogeneous isotropic medium. Comparing it with the evolution of standard Laguerre-Gaussian beams with n=0 and m≠0 in the crystal, we have revealed that the additional elliptic deformation of the extraordinary beam results in topological reactions that essentially distort the field structure for the account of different rotation rates of the vortex row originated from the centred degenerate optical vortex and the conoscopic pattern. We have predicted conversion of the vortex topological charge at the beam axis similar to that in astigmatic lenses and analysed the radical differences with this process. We have revealed synchronic oscillations of the spin angular momentum and the sign of the vortex topological charge at the beam axis.