Topological edge states of Kekulé-type photonic crystals induced by a synchronized rotation of unit cells

Abstract

Generating and manipulating Dirac points in artificial atomic crystals has received attention especially in photonic systems due to their ease of implementation. In this paper, we propose a two-dimensional photonic crystal (PC) made of a Kekulé lattice of pure dielectrics, where the internal rotation of cylindrical pillars induces optical Dirac degeneracy-breaking. Our calculated dispersion reveals that the synchronized rotation reverses bands and switches parity as well so as to induce topological phase transition. Our simulation demonstrates that such topologically protected edge states can achieve robust transmission in almost arbitrarily-deformed defect waveguides and therefore provides a pragmatically tunable scheme to achieve reconfigurable topological phases.