Ultra-thin Underwater Acoustic Metasurface with Multiply Resonant Units

TL;DR

This paper introduces an ultra-thin underwater acoustic metasurface with multiply resonant units that effectively manipulate sound waves, enabling applications like anomalous reflection, focusing, and cloaking in water.

Contribution

It presents a practical, water-compatible acoustic metasurface with multiple resonances and a novel unit design, overcoming limitations of previous rigid-material-based metasurfaces.

Findings

Achieves effective anomalous reflection, focusing, and cloaking in water.

Constructed using real materials, not relying on ideal rigid materials.

Thickness is about two orders of magnitude smaller than the wavelength in water.

Abstract

This paper describes a new kind of acoustic metasurface with multiply resonant units, which have previously been used to induce multiple resonances and effectively produce negative mass density and bulk/shear moduli. The proposed acoustic metasurface can be constructed using real materials and does not rely on an ideal rigid material. Therefore, it can work well in a water background. The thickness of the acoustic metasurface is about two orders of magnitude smaller than the acoustic wavelength in water. The design of a unit group is proposed to avoid the phase discretization becoming too fine in such a long-wavelength condition. We demonstrate that the proposed acoustic metasurface achieves good performance in anomalous reflection, focusing, and carpet cloaking.