Robust ultra-high-Q Fano resonance for topological corner and ring-cavity mode coupling in Kagome photonic systems

Abstract

Corner and edge states in higher-order topological insulators provide new degrees of freedom for manipulating light propagation. Our research demonstrates that the topological waveguide coupled to the corner and edge states of the triangular cavity obtains a topological corner mode as narrow resonance and a topological ring-cavity mode as broad resonance, respectively. By adjusting the size of the dielectric column at the apex of the triangular cavity, the two modes can be coherently coupled at the same frequency position and obtain a high-Q Fano resonance. This Fano resonant has excellent robustness for unavoidable defects in the manufacturing process, paving the way for the design of high-performance lasers, switches, and other micro-nano integrated photonics devices.