Realization of terahertz frequency selecting based on topological edge states with kagome photonic crystals

Topological photonic insulators provide a novel approach to achieve high-efficiency terahertz transmissions due to the presence of the topological edge states. In this work, the frequency ranges of the topological edge states can be controlled by varying the radius of rods in the kagome lattice and the distance between them. In addition, a gap can be generated between two different frequency ranges and the frequency selecting functions can be realized by constructing different types of domains. Similarly, sandwich a non-trivial photonic crystal between two trivial ones also capable of frequency selection for its topological edge states. Our findings suggest that this work has significant potential for applications in photonic integrated devices.