Elastic topological resonator in pseudo-spin Hall edge states

Abstract

This paper proposes an elastic topological resonator derived from the Kekulé tight-binding model, which enables the quantum spin Hall effect (QSHE). Band inversion in the spin system is realized through fine-tuning the intracellular coupling constants. With full-wave simulations, the topological interface configurations demonstrate the robust spin-locked edge state transport characteristic, featuring excellent fidelity via defects and anti-direct transmission. Then, a hexagonal resonator is located beside the straight waveguide to achieve multiple effective coupling directed by the edge state. The effect of the distance between the straight waveguide and the hexagonal part is further analyzed on the number of the resonant mode. Based on the functionally graded design concept, the topological resonance rainbow is also proposed to spatially separate distinct frequency components in accordance with projected band branches, to realize the progressive propagation of Lamb waves along the resonator route. Our work provides a novel mechanism for manipulating elastic waves with topological edge states, which is anticipated to serve as a foundation for creating programmable sensors and multifunctional testing equipment.