Tunable topological edge states based on anomalous scattering.

Abstract

The present work combines traditional dielectric materials with metal foils to form composite scatterers and constructs a two-dimensional square lattice photonic crystal, from which its band topology is achieved. Photonic bandgap (PBG) arises from local Mie scattering resonances between adjacent structures, analogous to the role of atomic energy levels in a crystal. The energy levels of the composite scatterers can be controlled by rotation, thus manipulating the PBG and topological properties. Topological phase transition is realized by altering the rotation angle of the composite scatterers in the unit cell. A programmable topological insulator with a single-chip control system (SCCS) is developed to verify numerical results. This design not only achieves tunable topological edge states (TES) but also enables arbitrary coding.