3D acoustic metasurface carpet cloak based on groove structure units

A 3D acoustic metasurface carpet cloak (AMCC) based on groove structure units is proposed and investigated. The key idea behind this acoustic invisibility is the phase compensation via local phase modulation, and thus a cloak with a thickness of only of a half wavelength could be designed for objects with arbitrary geometric shapes and sizes. We first demonstrate the cloaking effect of hiding a conical object numerically, and find that the working bandwidth of the designed AMCC is from 6200–7500 Hz. Further experimental results are in good agreement with the numerical simulations, verifying that the AMCC works well for the normal incident wave and the small-angled incident waves. As another example, we also confirm that the proposed AMCC can hide a semispherical object. The present AMCC is thin, has a simple geometrical structure, and is easy to implement, which benefits future realistic applications.