Topological crystalline protection in a photonic system

TL;DR

This paper proposes a method to realize topologically protected photonic boundary states using crystalline symmetry, mapping a 1D system to a 2D lattice with opposite magnetic fields and Chern numbers, and tests their robustness through simulations.

Contribution

It introduces a novel mechanism for topological protection of photonic boundary states based on crystalline symmetry and mirror parity, extending topological insulator concepts to photonics.

Findings

Photonic boundary states can be protected by crystalline symmetry.

Edge modes are robust against certain perturbations in simulations.

The model maps to a 2D topological mirror insulator with opposite Chern numbers.

Abstract

Topological crystalline insulators are a class of materials with a bulk energy gap and edge or surface modes, which are protected by crystalline symmetry, at their boundaries. They have been realized in electronic systems: in particular, in SnTe. In this work, we propose a mechanism to realize photonic boundary states topologically protected by crystalline symmetry. We map this one-dimensional system to a two-dimensional lattice model with opposite magnetic fields, as well as opposite Chern numbers in its even and odd mirror parity subspaces, thus corresponding to a topological mirror insulator. Furthermore, we test how sensitive and robust edge modes depend on their mirror parity by performing time dependent evolution simulation of edge modes in a photonic setting with realistic experimental parameters.