Topological features of vector vortex beams perturbed with uniformly polarized light

TL;DR

This paper investigates how perturbations in vector vortex beams create stable polarization singularities, with potential applications in weak field measurement techniques like singularimetry.

Contribution

It demonstrates how symmetry-breaking perturbations produce stable polarization singularities in vector vortex beams, extending analysis to higher topological charges and varying intensities.

Findings

Perturbations lead to stable singularities in vector vortex beams.

Control of singularity formation through amplitude variation.

Insights into polarization patterns for weak field measurement.

Abstract

Optical singularities manifesting at the center of vector vortex beams are unstable, since their topological charge is higher than the lowest value permitted by Maxwell's equations. Inspired by conceptually similar phenomena occurring in the polarization pattern characterizing the skylight, we show how perturbations that break the symmetry of radially symmetric vector beams lead to the formation of a pair of fundamental and stable singularities, i.e. points of circular polarization. We prepare a superposition of a radial (or azimuthal) vector beam and a uniformly linearly polarized Gaussian beam; by varying the amplitudes of the two fields, we control the formation of pairs of these singular points and their spatial separation. We complete this study by applying the same analysis to vector vortex beams with higher topological charges, and by investigating the features that arise when increasing the intensity of the Gaussian term. Our results can find application in the context of singularimetry, where weak fields are measured by considering them as perturbation of unstable optical beams.