Acoustic multi-mode interference in glide-reflection symmetric interfaces

This study presents a glide-reflection (GR) symmetrical phononic crystal (PC), and the mismatch of the Wannier center between two PCs leads to the emergence of edge states. By stacking multiple GR symmetric PC interfaces, the coupled edge states (CES) are found, which originate from the coupling between the adjacent interfaces. The multi-mode interference (MMI) effects of CESs were predicted based on finite element method simulation and confirmed by an acoustic experiment. In a further way, a topological edge state frequency splitter based on MMI effects was designed and demonstrated by both numerical simulations and experiments. Our research provides insights for the design of acoustic devices such as filters and couplers and may contribute to the advancement of acoustic signal processing.