Wavefront Modulation and Subwavelength Diffractive Acoustics with an Acoustic Metasurface

TL;DR

This paper introduces an acoustic metasurface made of tapered labyrinthine metamaterials that can steer beams, convert surface waves, and achieve negative refraction, enabling advanced acoustic wave control with ultrathin profiles.

Contribution

It presents a novel design of an acoustic metasurface using tapered labyrinthine structures, demonstrating functionalities similar to electromagnetic metasurfaces.

Findings

Achieved beam steering consistent with generalized Snell's law

Demonstrated surface wave conversion and negative refraction

Enabled high-efficiency sound manipulation

Abstract

Metasurfaces are a family of novel wavefront shaping devices with planar profile and subwavelength thickness. Acoustic metasurfaces with ultralow profile yet extraordinary wave manipulating properties would be highly desirable for improving the performance of many acoustic wave-based applications. However, designing acoustic metasurfaces with similar functionality as their electromagnetic counterparts remains challenging with traditional metamaterial design approaches. Here we present a design and realization of an acoustic metasurface based on tapered labyrinthine metamaterials. The demonstrated metasurface can not only can steer an acoustic beam as expected from the generalized Snell s law, but also exhibits various unique properties including surface wave conversion, extraordinary beam-steering and apparent negative refraction through higher-order diffraction. Such designer acoustic metasurfaces provide a new design methodology for acoustic signal modulation devices and may be useful for applications such as beam-steering, surface wave manipulation, high efficiency sound absorption, acoustic imaging and ultrasound lens design.