Reflected Wavefront Modulation with Phase Array by Using Acoustic Metasurface

Acoustic metasurface has attracted increasing attention due to the ability of manipulating the transmitted and reflected phase of waves to generate various acoustic functionalities with planar layer of sub-wavelength structure. We design an acoustic metasurface with a semi-closed and nested slotted tube array, and it possesses the capacity of modulating the reflected phase with sub-wavelength thickness (about λ/23). The reflected phase shifts can be obtained from 0 to 2π by different rotation angles of internal slotted tubes. The theoretical results agree well with the numerical results by a finite element method. The results show that some excellent wavefront manipulations are demonstrated with the phase array by using acoustic metasurface such as anomalous reflection and sub-wavelength flat focusing. The design may offer a path for acoustic manipulation and promote the potential applications of acoustic metasurface in low frequency noise control, acoustic imaging and cloaking.