Optical reflection signature of an axion dielectric with magnetic current

TL;DR

This paper explores how an axion-like dielectric with magnetic current affects optical reflection, deriving conditions for total internal reflection, polarization changes, and Kerr effects, revealing signatures of axion electrodynamics in optical responses.

Contribution

It provides the first detailed derivation of Fresnel coefficients and reflection conditions for an axion dielectric with magnetic current, including polarization and Kerr effect analysis.

Findings

Total internal reflection conditions depend on system parameters and frequency.

Null reflection (Brewster angles) are identified for specific frequencies and angles.

Maximum Kerr ellipticity occurs at certain frequencies, indicating axion signatures.

Abstract

In this work, we investigate the reflection properties on the interface between an ordinary dielectric medium and a dielectric supporting a magnetic current (equivalent to a dielectric governed by axion electrodynamics). Considering the usual Maxwell equations and constitutive relations, we derive the general Fresnel coefficients for reflection for an incident wave with $s$ and $p$ polarization, assuming an isotropic magnetic current on a dielectric substrate. We determine all total internal reflection and critical angles (Brewster angles) conditions, which are given by strict relations between all relevant electromagnetic quantities of the system and the frequency. For $s$- and $p$-polarized incident waves, total internal reflection can occur under certain conditions on the constitutive parameters (for each propagating mode) at specific frequency windows and certain incidence angle intervals. All possible conditions to define critical angles for null reflection are determined. This scenario allows polarization changes by reflection. Considering a $p$-polarized incident wave, the frequency and the Brewster angle, allowing null reflection for both propagating modes, are determined. The Goos-H\"anchen shift and the complex Kerr rotation are also evaluated. The Kerr ellipticity angle presents a frequency-dependent behavior, also reported in Weyl semimetals, having maximum values $\eta_{Kerr}=\pm \pi/4$ for specific values of frequency, which may work as a signature of this axion chiral dielectric.