All-pass phase shifting achieved by acoustic unidirectional guided resonances

Phase manipulation of sound is an important function for many acoustic applications. Here, we apply temporal coupled mode theory to demonstrate that sound all-pass phase shifting, which means that acoustic waves propagate with unit amplitude but have strong phase changes, can be achieved by utilizing acoustic unidirectional guided resonances (AUGRs). An oblique layered acoustic structure with inversion-symmetry is proposed to realize AUGRs that radiate only to one side of the structure. Full-wave simulations are employed to validate the theoretical analysis. With the strong phase-only resonances, our proposed acoustic structure can find applications in acoustic filtering and sensing.