Spin-orbit interactions induced by light drag in moving media

TL;DR

This paper demonstrates that spin-orbit interactions of light can occur in moving media via light-dragging effects, revealing a new fundamental mechanism involving Berry phase and polarization rotation, with potential applications in light control.

Contribution

It introduces a novel mechanism for spin-orbit interactions in moving media through Berry phase induced by vorticity, expanding understanding beyond inhomogeneous materials.

Findings

SOIs can emerge in moving media via light drag effects

Berry phase induced by vorticity causes polarization rotation

New methods to control light using moving media are proposed

Abstract

Spin-orbit interactions (SOIs) of light are manifestations of coupling between components of light's angular momentum. They are at play in most basic optical processes, offering opportunities both to understand their fundamental origin and to control light in novel ways. Because SOIs become significant at subwavelength scale, they have largely been explored in the context of inhomogeneous materials exhibiting wavelength-scale structures, and notably metamaterials. Here we demonstrate that spin-orbit interactions can in fact analogously emerge in moving matter through the well-known light-dragging effects. SOIs in moving media are shown to manifest through a Berry phase induced by vorticity, which then leads to a rotation of the wave's polarization. In bringing together electrodynamics of moving media and SOIs of light, our work not only paves the way for the discovery of new fundamental effects but also uncovers novel means to harness SOIs to control light.