Zhu Yifan, Cao Liyun, Merkel Aurélien, Fan Shi-Wang, Vincent Brice, Assouar Badreddine
Université de Lorraine, CNRS, Institut Jean Lamour, Nancy, 54000, France.
Nat Commun. 2021 Dec 6;12(1):7089. doi: 10.1038/s41467-021-27403-4.
Integrating different reliable functionalities in metastructures and metasurfaces has become of remarkable importance to create innovative multifunctional compact acoustic, optic or mechanical metadevices. In particular, implementing different wave manipulations in one unique material platform opens an appealing route for developing integrated metamaterials. Here, the concept of Janus acoustic metascreen is proposed and demonstrated, producing two-faced and independent wavefront manipulations for two opposite incidences. The feature of two-faced sound modulations requires nonreciprocal phase modulating elements. An acoustic resonant unit cell with rotating inner core, which produces a bias by a circulating fluid, is designed to achieve high nonreciprocity, leading to decoupled phase modulations for both forward and backward directions. In addition, the designed unit cell consisting of tunable phase modulators is reconfigurable. A series of Janus acoustic metascreens including optional combinations of extraordinary refraction, acoustic focusing, sound absorption, acoustic diffusion, and beam splitting are demonstrated through numerical simulations and experiments, showing their great potential for acoustic wavefront manipulation.
在超结构和超表面中集成不同的可靠功能对于创建创新的多功能紧凑型声学、光学或机械超器件已变得极为重要。特别是，在一个独特的材料平台上实现不同的波操控为开发集成超材料开辟了一条有吸引力的途径。在此，提出并展示了双面声学超屏的概念，它能对两个相反入射方向产生双面且独立的波前操控。双面声音调制的特性需要非互易相位调制元件。设计了一种带有旋转内芯的声学谐振单元，其通过循环流体产生偏置，以实现高非互易性，从而实现正反方向的解耦相位调制。此外，由可调相位调制器组成的设计单元是可重构的。通过数值模拟和实验展示了一系列双面声学超屏，包括异常折射、声聚焦、吸声、声扩散和波束分裂的可选组合，显示出它们在声波前操控方面的巨大潜力。
