Switchable broadband acoustic propagation via reconfigurable metasurface

Dynamically switchable acoustic propagation shows potential applications in noise control and medical engineering. Even if the reconfigurable metasurfaces (RMs) have been proposed to switch on/off acoustic propagation, the narrow working frequency and restricted incident angle limit the potential applications. To overcome the limitations, a RM with adjustable refractive index profile is designed in a frequency broadband. By adjusting the refractive index profile of the RM, both theoretical analysis and numerical simulations demonstrate that the proposed RM can effectively switch on and off acoustic propagation in the frequency range [2.9–4.1 kHz ] and incident angle range [$0^{\circ }-60^{\circ }$ ]. The underlying mechanism originates from the diffraction law of phase gradient metagrating, where the refractive index modulation of the RM enables precise control over acoustic diffraction phenomena. The proposal features broadband and large incident angle range, and would contribute to the acoustic barriers and medical ultrasound therapy.