Spatial separation of spoof surface acoustic waves on the graded groove grating

Abstract

In this paper, a rigid surface decorated with an array of grooves with graded widths is proposed to get spatial separation of the spoof surface acoustic waves. Because of the intermodal coupling between forward and backward modes on the graded structure, the spoof surface acoustic waves with different frequencies stop propagating ahead and reflect back at different positions of the graded groove grating. The intensity of acoustic field is effectively enhanced near the propagation-stop position due to the slow group velocity. We believe that such system with the capability of energy concentration and wave spatial arrangement by frequencies has potential applications in acoustic wave coupling and absorption.