Covariant formulation of spin optics for electromagnetic waves

TL;DR

This paper develops a spin optics framework for electromagnetic waves in curved spacetime, revealing polarization-dependent deviations in light trajectories and drawing analogies with condensed matter phenomena.

Contribution

It introduces a subleading order geometric optics expansion called spin optics, incorporating helicity-dependent corrections for electromagnetic wave propagation in curved spacetime.

Findings

Polarization-dependent deviation of light rays from geodesics.

Derivation of propagation and polarization equations in spin optics.

Analogy established with optical Magnus effect in condensed matter.

Abstract

We develop geometric optics expansion up to the subleading order for circularly polarized electromagnetic waves on curved spacetime. This subleading order geometric optics expansion, in which the conventional eikonal function is modified by inserting a carefully chosen helicity-dependent correction, is called spin optics. We derive the propagation and polarization equations in the spin optics approximation as electromagnetic waves travel in curved spacetime. Polarization-dependent deviation of the light ray trajectory from the geodesic, describing the gravitational spin Hall effect, is observed. We also establish an analogy with the related phenomena (optical Magnus effect) of condensed matter physics.