Topological polycrystal: A new approach to configurable, multiband topological photonic circuitry

Molding the flow of light--whether confined to localized regions or propagating in free space--remains crucial for modern integrated photonics. The advancement of the multi-channel, programmable optical waveguide and coupler arrays has enabled us to develop photonic integrated circuits (PICs) as a viable alternative to electronic ones, overcoming limitations in processing speed, bandwidth, and efficiency across the optical-to-microwave spectrum.