Deformations of circularly polarized Bessel vortex beam reflected and transmitted by a uniaxial anisotropic slab.

Bessel vortex beams are widely studied, since their intensity is independent of the propagation distance, and also their original field intensity distribution can be reconstructed after passing through an obstacle. Therefore, such beams are more advantageous for long-distance communication, optical imaging, and other potential applications. Based on the expansion of electromagnetic fields in terms of vector wave functions, in this investigation a method has been proposed to study the reflection and transmission of an incident circularly polarized Bessel vortex beam by a uniaxial anisotropic slab. The expansion coefficients of a circularly polarized Bessel vortex beam are derived by use of the cylindrical vector wave functions. The magnitude profiles of the electric field amplitude and phase, as well as the distribution of orbital angular momentum (OAM) states for both the reflected and transmitted beams, are numerically simulated and discussed. The effects of dielectric tensor and incident angle on the propagation characteristics of a circularly polarized Bessel vortex beam are analyzed. The observed results indicate that the contours of the electric field components cannot retain circularly symmetric structures; the distortion of phase distribution is obvious, and except for the predominant OAM state, other OAM states are derived, particularly for the reflected beam. Although few OAM states emerge in the transmitted beam, the predominant OAM state is still the same as that of the incident Bessel vortex beam.