One-way self-collimated acoustic beams in two-dimensional asymmetric sonic crystals with circulating fluids

Abstract

We theoretically realized the one-way self-collimation effect of acoustic beams in two-dimensional sonic crystals (SCs), which are composed of irregular rigid rods surrounded by circulating fluids. The parity symmetry (P symmetry) and time-reversal symmetry (T symmetry) of the circulating-fluid SCs (CFSCs) are broken by the asymmetric crystal lattice and the circulating fluids. A large isolation of >30 dB with a maintained wavefront and frequency is realized for output acoustic beams launched in opposite directions. By applying the gradient angular velocities of the circulating fluids, the one-way self-collimated acoustic beams can be bent gradually, yielding an acoustic mirage effect. The one-way self-collimation in CFSCs provides an avenue for manipulating acoustic beams independently of the nonlinearity and mode conversion.