Unidirectional transmission of acoustic waves based on asymmetric excitation of Lamb waves

In this paper, an easily fabricated acoustic system has been demonstrated to gain unidirectional transmission with good performance. The unidirectional acoustic transmission originates from the asymmetric excitation of zero-order anti-symmetric Lamb modes. The results show that the single-sided patterned ridges on the steel plate enhance the scattering of the incident waves from the structured side and improve the coupling of the Lamb modes in the plate with them, which leads to high transmission ratio and great transmission difference value of acoustic waves along the opposite directions. All the experimental results show good agreement with the numerical simulations. The proposed acoustic system has potential applications in underwater acoustic and medical ultrasonic devices. (C) 2013 AIP Publishing LLC [http://dx.doi.org/10.1063/1.4802254]