Modulation of acoustic waves by a broadband metagrating

Yihe Wang,Xiaojun Liu,Ying Cheng

doi:10.1038/s41598-019-43850-y

Abstract

Metasurface has recently attracted a lot of attentions for controlling wave fields. Based on the diffraction effects of phase gratings, we demonstrate a broadband acoustic metagrating which can concentrate the diffracted waves in the first (±1) orders and achieve multifunctional wave steering such as broadband anomalous diffraction. In the acoustic metagrating, the subwavelength rectangular waveguides (SRWs) function as the periodic elements to replace the fences in ordinary gratings. Thus, we can achieve a group of phase delay from 0 to 2π independently with frequency just by reconfiguring the relative locations of the effective apertures. With the iterative algorithm, the acoustic metagrating can be used to record the phase profile and then control the output waveform. We further demonstrate that the broadband metagrating can be used to achieve the acoustic Gaussian beam. By rotating the periodic elements into a two-dimensional structure, the Bessel beam is further obtained.

Highlights

IntroductionBased on the diffraction effects of phase gratings, we demonstrate a broadband acoustic metagrating which can concentrate the diffracted waves in the first (±1) orders and achieve multifunctional wave steering such as broadband anomalous diffraction
Metasurface has recently attracted a lot of attentions for controlling wave fields
We demonstrate a broadband acoustic metagrating by reconfiguring the typical diffraction effects

Summary

Introduction

Based on the diffraction effects of phase gratings, we demonstrate a broadband acoustic metagrating which can concentrate the diffracted waves in the first (±1) orders and achieve multifunctional wave steering such as broadband anomalous diffraction. The subwavelength rectangular waveguides (SRWs) function as the periodic elements to replace the fences in ordinary gratings. In order to control wave trace, the metasurface must provide corresponding phase profile in different positions. This phase profile is usually derived from the generalized laws of diffraction[18], leading to the inherent dependence on the working frequency. The metagrating is composed of periodic structured elements consisted by subwavelength rectangular waveguides (SRWs) to achieve the steering of acoustic waves. We further determine the multifunction of the metagrating in wave steering, such as achievement of acoustic Gaussian and Bessel beams

Methods

Results

Conclusion