Reflected wavefronts modulation with acoustic metasurface based on double-split hollow sphere

Abstract

Metasurfaces with sub-wavelength thickness and planar profile have exhibited abnormal manipulation to waves that could not be realized by traditional materials. Here, we present an acoustic metasurface (AMS) model composed of double-split hollow sphere (DSHS) resonator arrays with the functionality of modulating reflected wavefronts at will. By tailoring the split-hole diameter of DSHS, the AMS can be designed to cover 2π phase shifts with a step of π/4. The acoustic waves perpendicularly and obliquely incident on the AMS can be reflected at any angle, including anomalous reflection and negative reflection. These anomalous manipulations of the reflected wave are simulated to fulfill the generalized Snell’s law by projecting suitable phase gradient. Such AMS provides another path to acoustic applications such as acoustic imaging, cloaking, beam steering devices.