Tunable perfect negative reflection based on an acoustic coding metasurface

Abstract

Artificial manipulation of acoustic waves is a highly active research area, in which negative reflection is an exotic phenomenon. Emerging acoustic coding metasurfaces (ACMs) show great power in controlling acoustic waves. Here, we propose an ACM, where the state "0" or "1" is achieved by pushing up or pressing down a rigid rectangular strip. The ACM with a tunable coding sequence can adjust the direction of negative reflection as well as suppress the specular reflection. The feasibility of the ACM is demonstrated by totally reflecting the incident acoustic waves from 22 ° to the directions of - 39 °, - 47 °, and - 61 °. Furthermore, the ACM can spread the incident white noise into its acoustic spectral components like rainbows. This work may open diverse routes toward reconfigurable acoustic metasurfaces that are critical for practical functional devices, which are promising in potential applications including acoustic beam steering, retro-reflection, and surface wave sensing.