Dual-band multi-frequency wave routing based on photonic square-root topological insulators

Previous studies on topological dual-band frequency routers have focused on routing signals separately within two distinct frequency bands. However, the potential of dual topological bands has not been fully explored, particularly the possibility of each band supporting multiple frequency channels. Here, we propose a dual-band multi-frequency wave routing based on photonic square-root topological insulators. By introducing tailored perturbations into a decorated honeycomb lattice, we open two band gaps and design two distinct topological interfaces to obtain multi-frequency topological edge states. As a result, our single structure enables the routing of four different frequency ranges. This work provides a new approach for advanced integrated devices based on photonic square-root topological insulators.