Reconfigurable topological waveguide based on honeycomb lattice of dielectric cuboids

We show that the photonic crystal (PhC) made of dielectric cuboids with their centers forming a honeycomb lattice is characterized by a topological index when the longer sides of six cuboids point towards the center of hexagonal unit cell. While the symmetry regarding the center of unit cell is preserved, the symmetry regarding honeycomb sites is broken, which opens a bandgap in the Dirac dispersion of honeycomb structure and induces a band inversion between modes and modes. Rotating cuboids around their individual centers closes the bandgap and reopens a trivial bandgap. We discuss that this feature can be exploited for realizing a reconfigurable topological waveguide.