Acoustic metascreen for broadband wavefront manipulation with stationary phase gradients

¹ Institute of Acoustics, School of Physics Science and Engineering, Tongji University - Shanghai 200092, China
² State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences - Beijing 100190, China

Received: 4 November 2023
Accepted: 14 December 2023

Abstract

The development of an efficient acoustic metascreen utilizing artificial micro-structured metamaterials holds paramount importance for the manipulation of acoustic wavefronts. However, the expansive broadband capability of such metascreens is often compromised due to the variations in amplitude and phase profiles of the conceived structures at different frequencies. To address this issue, we introduce a broadband metascreen composed of several interconnected acoustic cavities. The concept is substantiated by the theoretical explication of the abrupt cross-section tube model. The resultant metascreen demonstrates high transmission efficiency and maintains a consistent phase profile over a wide frequency band, which implies that the relative phase disparities amongst neighboring pixels are retained at uniform intervals across the entire frequency spectrum, enabling the distinct broadband functionality of the metascreens developed. Through both simulations and experimental measurements, we exhibit the ability of the metascreen to manipulate the wavefront of transmitted waves, accomplishing acoustic focusing and self-bending across multiple frequencies. Our research paves the way for a novel and multifunctional method to manipulate broadband wavefronts through transmissive grooved acoustic metamaterial, offering a practical and promising methodology to develop advanced acoustic apparatuses.