Broadband Negative Reflection of Underwater Acoustic Waves from a Simple Metagrating: Modeling and Experiment

Bernard, Simon; Chikh-Bled, Feriel; Kourchi, Hasna; Chati, Farid; Léon, Fernand

doi:10.1103/physrevapplied.17.024059

Cited by 7 publications

(4 citation statements)

References 32 publications

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“…Their design reroutes a normally incident wave to extreme angles with unitary efficiency in reflection. It was further shown that such a metagrating can be reconfigured (by varying the orientation of meta-units and the distance above the rigid surface) to cater to a wide range of angles and frequencies [88,89]. Without the rigid surface, a bianisotropic metagrating using a singlelayer of identical meta-units with broken spatial symmetry can realize both asymmetric wave transmission and reflection [90], while a multi-layer bianisotropic metagrating gives rise to asymmetric beam splitting [91].…”

Section: Non-local Effects From Radiation Couplingmentioning

confidence: 99%

“…Therefore, fluid-structure interaction becomes far more important than for airborne sound and it could result in strong non-local interaction between the meta-units in water. This has made underwater metasurfaces a new playground for exploiting the physics and applications of non-local effects [76,78,83,89,94,[99][100][101][102]. For non-local underwater metagratings, the non-local interaction between the meta-units induced by fluid-structure interaction can be carefully engineered via an optimization method (e.g.…”

Section: Non-local Effects From Radiation Couplingmentioning

confidence: 99%

“…genetic algorithm) (figures 6(e) and (f)). In this way, by using meta-units such as cylindrical scatterers [99,100], cylinders with slits [89], side-branched Helmholtz resonators (HRs) [94], and grooves [76,78,101,102], various functions including anomalous reflection and transmission, retroreflection, beam splitting, and highly asymmetric transmission can be realized for underwater sound with desired efficiency.…”

Section: Non-local Effects From Radiation Couplingmentioning

confidence: 99%

“…Indeed, Willis coupling media have shown their bianisotropic (i.e. asymmetric) responses in the context of metasurfaces [87][88][89][90][91]. The majority of Willis coupling media that have been studied to date are lossless and do not provide access to EPs.…”

Section: Non-hermitian Acoustics In Waveguides (1d)mentioning

confidence: 99%

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Non-local and non-Hermitian acoustic metasurfaces

Wang,

Dong,

et al. 2023

Rep. Prog. Phys.

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Acoustic metasurfaces are at the frontier of acoustic functional material research owing to their advanced capabilities of wave manipulation at an acoustically vanishing size. Despite significant progress in the last decade, conventional acoustic metasurfaces are still fundamentally limited by their underlying physics and design principles. First, conventional metasurfaces assume that unit cells are decoupled and therefore treat them individually during the design process. Owing to diffraction, however, the non-locality of the wave field could strongly affect the efficiency and even alter the behavior of acoustic metasurfaces. Additionally, conventional acoustic metasurfaces operate by modulating the phase and are typically treated as lossless systems. Due to the narrow regions in acoustic metasurfaces' subwavelength unit cells, however, losses are naturally present and could compromise the performance of acoustic metasurfaces. While the conventional wisdom is to minimize these effects, a counter-intuitive way of thinking has emerged, which is to harness the non-locality as well as loss for enhanced acoustic metasurface functionality. This has led to a new generation of acoustic metasurface design paradigm that is empowered by non-locality and non-Hermicity, providing new routes for controlling sound using the acoustic version of 2D materials.This review details the progress of non-local and non-Hermitian acoustic metasurfaces, providing an overview of the recent acoustic metasurface designs and discussing the critical role of non-locality and loss in acoustic metasurfaces. We further outline the synergy between non-locality and non-Hermiticity, and delineate the potential of using non-local and non-Hermitian acoustic metasurfaces as a new platform for investigating exceptional points (EPs), the hallmark of non-Hermitian physics. Finally, the current challenges and future outlook for this burgeoning field are discussed.

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