Making sound vortices by metasurfaces

TL;DR

This paper introduces a metasurface design based on the Huygens-Fresnel principle to generate sound vortex beams in air, validated through simulations and experiments, with potential applications like torque exertion.

Contribution

It presents a novel metasurface structure for creating sound vortices in airborne environments, combining design, simulation, and experimental validation.

Findings

Successful generation of sound vortex beams via the metasurface

Validation through full-wave simulations and experiments

Demonstration of torque effect on an absorbing disk

Abstract

Based on the Huygens-Fresnel principle, a metasurface structure is designed to generate a sound vortex beam in airborne environment. The metasurface is constructed by a thin planar plate perforated with a circular array of deep subwavelength resonators with desired phase and amplitude responses. The metasurface approach in making sound vortices is validated well by full-wave simulations and experimental measurements. Potential applications of such artificial spiral beams can be anticipated, as exemplified experimentally by the torque effect exerting on an absorbing disk.