Multifunctional Asymmetric Sound Manipulations by a Passive Phased Array Prism

We report the theoretical and experimental realization of four types of passive phased array prisms with various asymmetric acoustic manipulations (AAMs) in air. The designed prisms consist of 31 transmitted unit cells of phase manipulation, which are composed of a n layer symmetric Helmholtz resonator (SHR) unit cell. Based on asymmetric phase distributions created by the nonparallel characteristic of exit interfaces on both sides of the structures, we can design a passive prism with asymmetric acoustic transmission (AAT) in which its fractional bandwidth can reach about 0.26. More interestingly, by adjusting the parameter of the SHR unit cells in the prism, we realize three other types of AAMs with the same mechanism, such as bidirectional acoustic insulation, asymmetric acoustic focusing, and reversed AAT. The proposed prisms have the advantages of broad bandwidth, multifunctional AAM, and passive structure as well as being easy to fabricate, and have great potential applications in integrated sound devices.