# Topologically non-trivial photonic surface degeneracy in a photonic metamaterial

## TL;DR

This paper demonstrates a topologically charged photonic surface degeneracy in a helix metamaterial, supported by Chern number calculations and Fermi arcs, revealing higher-dimensional topological features in photonics.

## Contribution

It introduces topologically non-trivial surface degeneracy with higher dimension in photonics, supported by theoretical calculations and adaptable to different frequency regimes.

## Key findings

- Identification of topologically charged surface degeneracy in helix structures
- Support of topological phase by Chern number and Fermi arcs
- System operates in both metamaterial and photonic crystal regimes

## Abstract

The recent development of topological photonics has revealed a variety of intriguing phenomena such as Weyl degeneracy. However, topologically non-trivial degeneracy with higher dimension has not been reported in photonics. In this Letter, topologically charged photonic surface degeneracy in a helix structure possessing two-fold screw symmetry is demonstrated. Calculated Chern number and photonic Fermi arcs support topological phase of the surface degeneracy. We also show that the photonic system can work in both metamaterial and photonic crystal regime, which have an order of magnitude different frequency range by the choice of material for the helix. This work suggests the possibilities of unprecedented photonic topological features with higher dimensions.