Non-centric cavity-based acoustic metasurface: Enabling full phase modulation

In this paper, an acoustic metasurface design is presented in which the transmitted phase may be tuned while preserving a high amplitude of transmission. To achieve full transmission with an arbitrary phase, the cavity is coupled with the coiling metamaterial to provide the desired level of impedance match. Furthermore, the effects of its geometrical parameters are investigated. The proposed structure exhibits an appropriate phase modulation in the desired phase frame (i.e., [0, 2π]) with high amounts of amplitudes. It is shown that this can be obtained by precisely designing the geometrical parameters even when the key parameters (i.e., the number of unit cells and their width and thickness values) are constant. Ultimately, three metasurfaces have been designed to redirect, split, and focus the transmitted wave while the resulted wavefront amplitude is preserved, enabling an efficient modulation platform.