Enhancement of asymmetric acoustic transmission

We report both experimentally and theoretically that enhanced one-way acoustic transmission is realized by coupling a periodical grating with metal plates. This exotic acoustic phenomenon is attributed to the structure-induced resonant excitation of the leaky Lamb modes which arise from the coupling of the diffracted waves with the resonant surface states localized at the interface of the grating and the metal plate. More importantly, we further optimize the structure by introducing two inclined plates, which can convert the reflected energy into the transmitted energy. Our finding has great potential applications in ultrasonic devices. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4798277]