# Chiral Maxwell waves in continuous media from Berry monopoles

## TL;DR

This paper introduces a new method to predict topologically protected chiral electromagnetic modes at interfaces of continuous media, linking their existence to Berry monopoles without needing regularization or topological materials.

## Contribution

It presents a novel approach that relates topological charges in parameter space to electromagnetic modes, avoiding previous limitations like regularization or topological material requirements.

## Key findings

- Theoretical prediction of chiral modes based on Berry monopoles.
- Numerical confirmation of interface modes in gyrotropic media.
- No need for regularization or topological properties of materials.

## Abstract

We propose a method to predict the existence of topologically protected electromagnetic chiral modes between continuous media described by Maxwell's equations. The number and character of these modes is related to topological charges (Berry monopoles) in parameter space. Unlike the approaches proposed so far, our description does not require a regularization parameter at large $\mathbf{k}$ nor the materials to be topological on their own. The predictions of the theory are confirmed by additional numerical simulations of interfaces of gyrotropic media.