Wavefront manipulation based on transmissive acoustic metasurface with membrane-type hybrid structure

Jun Lan,Xiaozhou Liu,Yifeng Li,Xiaowei Zhang

doi:10.1038/s41598-018-32547-3

Abstract

We designed and demonstrated a gradient acoustic metasurface to manipulate the transmissive wavefront. The gradient metasurface is composed of eight elements based on membrane-type hybrid structures, whose thickness and width are about 1/5 and 1/20 of the incident wavelength, respectively. Here, we employ acoustic theory to analyze the transmission spectrum and phase gradient of the metasurface, the properties of high transmission efficiency and discrete phase shifts over the full 2pi range can be achieved simultaneously. By appropriate selection of the phase profile along the transverse coordinate of the metasurface or the angle of incident wave, the transmissive wavefront manipulations based on metasurface can be obtained as expected from the generalized Snell’s law, such as anomalous refraction, acoustic cloak based on flat focusing, acoustic self-bending beam, conversion of propagating wave to surface wave and negative refraction. Our gradient metasurface may have potential application in low-loss acoustic devices.

Highlights

The acoustic metasurfaces as a family of wavefront-shaping devices with planar profile have attracted tremendous interest
With the acoustic transmission line method (ATLM) and impedance theory, we can derive that the decorated membrane resonators possess the abilities of shaping the phase over the full 2π range and overcoming the impedance mismatching to enhance sound transmission
We firstly demonstrate the construction of the acoustic gradient metasurface

Summary

Introduction

The acoustic metasurfaces as a family of wavefront-shaping devices with planar profile have attracted tremendous interest. In this paper, the connection of four decorated membrane resonators provides an effective acoustic reactance to shift the phase of the incident acoustic wave over the whole 2π range and realize the highly efficient transmission. The distinct wavefront manipulations such as anomalous refraction, acoustic cloak based on flat focusing, acoustic self-bending beam, conversion of propagating wave to surface wave and negative refraction are demonstrated based on the generalized Snell’s law. These five wavefront manipulations are enabled by free manipulation of the transversal phase profile along the metasurface or the angle of incident wave

Methods

Results

Conclusion