Light drag in nonuniformly moving anisotropic media through the lens of gradient-index optics

TL;DR

This paper develops a method to analyze light ray trajectories in nonuniformly moving anisotropic media by extending gradient-index optics, accounting for Fresnel drag, and demonstrating its application to magnetized plasma.

Contribution

It introduces an analytical approach linking symmetries in velocity fields to effective wave indices for modeling light in anisotropic moving media.

Findings

Analytical ray trajectories in anisotropic media are derived.

Results agree with classical models in isotropic limits.

Application to magnetized plasma shows complex interplay of motion and anisotropy.

Abstract

The trajectory of light rays propagating through a nonuniformly moving anisotropic medium is determined by considering the Fresnel drag experienced by the wave at each point along the ray. By showing that symmetries in the velocity field manifest as symmetries in the effective wave index representing the moving medium, methods classically employed to model gradient index media are then used to obtain analytical forms for the ray trajectory. When applied to isotropic media, the results are verified to be consistent with those obtained using an optical (Gordon) metric. The potential of this method to model light rays in anisotropic media is finally demonstrated by considering waves in a nonuniformly moving magnetized plasma, exposing how nonuniform motion and anisotropy can compete with one another.