Topological creation and destruction of edge states in photonic graphene

TL;DR

This paper explores how uniaxial strain in photonic graphene causes topological phase transitions, leading to the creation and destruction of edge states, with both theoretical and experimental validation.

Contribution

It demonstrates the topological transition of classical light in photonic graphene through strain-induced merging of Dirac points and edge state manipulation.

Findings

Dirac points merge and annihilate under strain

Band gap formation occurs with uniaxial compression

Edge states are controllably created and destroyed

Abstract

We demonstrate theoretically and experimentally a topological transition of classical light in "photonic graphene": an array of waveguides arranged in the honeycomb geometry. As the system is uniaxially strained (compressed), the two unique Dirac points (present in the spectrum of conventional graphene) merge and annihilate each other, and a band gap forms. As a result, edge states are created on the zig-zag edge and destroyed on the bearded edge. These results are applicable for any 2D honeycomb-type structure, from carbon-based graphene to photonic lattices and crystals.