Kelvin's Chirality of Optical Beams

TL;DR

This paper introduces Kelvin's chirality, a form of geometrical chirality for optical beams, and demonstrates its physical significance and coupling to optical chirality through an experiment involving focused beams and planar media.

Contribution

It defines Kelvin's chirality as a new concept of geometrical chirality for optical beams and experimentally shows its coupling to optical chirality during light-matter interactions.

Findings

Kelvin's chirality is physically significant for structured light.

Experimental evidence of coupling between Kelvin's and optical chirality.

Highlights importance in light-matter interaction with inhomogeneous beams.

Abstract

Geometrical chirality is a property of objects that describes three-dimensional mirror-symmetry violation and therefore it requires a non-vanishing spatial extent. In contrary, optical chirality describes only the local handedness of electromagnetic fields and neglects the spatial geometrical structure of optical beams. In this manuscript, we put forward the physical significance of geometrical chirality of spatial structure of optical beams, which we term "Kelvin's chirality". Further, we report on an experiment revealing the coupling of Kelvin's chirality to optical chirality upon transmission of a focused beam through a planar medium. Our work emphasizes the importance of Kelvin's chirality in all light-matter interaction experiments involving structured light beams with spatially inhomogeneous phase and polarization distributions.