Transverse spin of light for all wavefields

TL;DR

This paper introduces a comprehensive formalism for describing and generating light fields with transverse spin angular momentum, revealing their prevalence in various optical phenomena and enabling new control over light's angular momentum properties.

Contribution

It provides a general mathematical framework to generate wave fields with transverse spin from any scalar wave, expanding understanding of light's angular momentum.

Findings

Transverse spin occurs in focused beams, plasmonic fields, and evanescent waves.

The formalism can generate transverse spin from arbitrary scalar fields.

This work unifies the description of transverse spin phenomena in optics.

Abstract

It has been known for a long time that light carries both linear and angular momenta parallel to the direction of propagation. However, only recently it has been pointed out that beams of light, under certain conditions, may exhibit a transverse spin angular momentum perpendicular to the propagation direction. When this happens, the electric field transported by the light rotates around an axis transverse to the beam path. Such kind of fields, although deceptively elusive, are almost ubiquitous in optics as they manifests in strongly focused beams, plasmonic fields and evanescent waves. In this work we present a general formalism describing all these phenomena. In particular, we demonstrate how to mathematically generate a wave field possessing transverse spin angular momentum density, from any arbitrarily given scalar wave field, either propagating and evanescent.