Diffraction of an Off-axis Vector-Beam by a Tilted Aperture

TL;DR

This paper investigates how a radially polarized vector beam's diffraction pattern is affected by an off-axis tilted aperture, revealing polarization and topological charge effects through experiments and simulations.

Contribution

It provides a combined experimental and theoretical analysis of orbital angular momentum effects in diffraction with tilted apertures, highlighting polarization separation and misalignment impacts.

Findings

Polarization degree proportional to spin angular momentum density

Clear separation of circular polarization regions based on topological charge

Good agreement between experimental results and model simulations

Abstract

Manifestations of orbital angular momentum induced effects in the diffraction of a radially polarized vector beam by an off-axis tilted aperture are studied both experimentally and theoretically. Experiments were carried out to extract the degree of circular polarization, which was shown to be proportional to the on-axis component of the spin angular momentum density. We report a clear separation of the regions of dominance of the right and left circular polarizations associated with positive and negative topological charges respectively, which is reminiscent of the standard vortex-induced transverse shift, albeit in the diffraction scenario. The experimental results are supported by model simulations and the agreement is quite satisfactory. The results are useful to appreciate the orbit-orbit related effects due to unavoidable misalignment problems (especially for vortex beams).