Optical Skyrmions of Vortex Darkness

TL;DR

This paper introduces Gauss-Stokes (GS) skyrmions, a new type of optical skyrmion naturally occurring in optical vortices, characterized by a concealed phase singularity and rich polarization textures, observed through focused fields.

Contribution

The study reveals the existence of GS skyrmions in scalar optical beams without shaping vector beams or superposing modes, expanding understanding of optical skyrmions.

Findings

Discovered GS skyrmions in optical vortices.

Observed skyrmionic polarization textures experimentally.

Linked phase singularity to polarization topology.

Abstract

We disclose the existence of a type of optical skyrmion, Gauss-Stokes (GS) skyrmions, that is naturally present in an optical vortex around its phase singularity. Contrary to previous research with optical skyrmions, we neither shape vector beams nor superpose different spatial modes and polarizations. In GS skyrmions, the phase singularity in the transversal field of a single monochromatic beam of uniform polarization (a scalar beam) is concealed by the axial field dictated by Gauss's divergence law, giving rise to a polarization singularity of undefined polarization plane. This singularity is enclosed by a rich skyrmionic polarization texture fulfilling a topological map and covering all the states of transverse-axial polarization. In our experiment, we facilitate the observation of a GS skyrmion with the predicted features using focused fields with enhanced axial component.