The generation of acoustic Airy beam with selective band based on binary metasurfaces: Customized on demand

Abstract

In this work, we present a type of binary metasurface (BM) to generate an acoustic Airy beam in air. Two coding bits, a rectangular cavity (bit “0”) and a waveguide with seven Helmholtz resonators (bit “1”), are adopted to construct the acoustic structure, which offers degrees of freedom to manipulate the transmitted field. The operating band is capable of customizing in an ultrabroadband of 3000–15 000 Hz owing to the linear-like phase shift and high transmittance of the coding bits. To verify the feasibility of the design, a BM with a certain parameter (w = 5) is fabricated with photosensitive resin via stereolithography, and the working band is customized as 4000–5500 Hz. The experiment results show that the apparent self-bending beam is able to be generated in a broadband, which agree well with the numerical simulation. In addition, we further demonstrate that self-focusing can be realized by taking advantage of two symmetrical BMs conveniently, which improve the functionality of the coding bits. These results may provide potential application in biomedical ultrasound and nondestructive testing.

Unidirectional acoustic metamaterials based on nonadiabatic holonomic quantum transformations

“…The metamaterial proposed in our work is a binary design, where only two phase responses, 0 and π, are required to achieve a desirable transmission field pattern. By utilizing the binary design, other fascinating beam-shaping behaviors such as focusing beam [77] and Airy beam [78] can be realized in addition to beam splitting. However, different from the construction of beam splitter by periodically arraying the acoustic coupler, the design of focusing beam or Airy beam generators requires more complicated phase arrangement of 0 and π.…”

Functional Acoustic Metamaterial Using Shortcut to Adiabatic Passage in Acoustic Waveguide Couplers

“…An acoustic waveguide (WG) coupler always serves as a functional device to achieve power transfer [29][30][31][32][33], mode conversion [34][35][36], or phase inversion [37][38][39] by taking advantage of the phononic crystals [40][41][42], Helmholtz resonators [43,44], or coiling-up particles [45][46][47][48]. Various fascinating phenomena, including focusing beam [49][50][51][52][53], splitting beam [31,48], self-bending beam [54,55] and vortex beam [56][57][58], can be observed by constructing acoustic devices integrated by WG couplers. Nevertheless, complicated structural designs pose challenges to modeling and analysis inevitably.…”

Underwater Transmitted Wavefront Manipulation Based on Bubble-Arrayed Acoustic Metasurfaces

“…To modulate waves in 2D scales, the concept of metasurfaces was proposed in optics [3] based on the generalized Snell's law (GSL) [4]. With the advantage of ultrathin and lightweight compact structure, the acoustic metasurface has also attracted broad attention in the past decade [5][6][7][8][9][10]. By intriguingly designing the functional units, multiple functionalities can be realized, such as abnormal reflection [11,12], negative refraction [13,14], beam focusing [15], vortex sources and perfect absorption [16][17][18][19], and self-bending beams [20].…”