Wen Xinhua, Cho Choonlae, Zhu Xinghong, Park Namkyoo, Li Jensen
Department of Physics, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China.
Photonic Systems Laboratory, Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, South Korea.
Sci Adv. 2024 May 31;10(22):eadm9673. doi: 10.1126/sciadv.adm9673.
Field transformation, as an extension of the transformation optics, provides a unique means for nonreciprocal wave manipulation, while the experimental realization remains a substantial challenge as it requires stringent material parameters of the metamaterials, e.g., purely nonreciprocal bianisotropic parameters. Here, we develop and demonstrate a nonreciprocal field transformation in a two-dimensional acoustic system, using an active metasurface that can independently control all constitutive parameters and achieve purely nonreciprocal Willis coupling. The field-transforming metasurface enables tailor-made field distribution manipulation, achieving localized field amplification by a predetermined ratio. The metasurface demonstrates the self-adaptive capability to various excitation conditions and can be extended to other geometric shapes. The metasurface also achieves nonreciprocal wave propagation for internal and external excitations, demonstrating a one-way acoustic device. The nonreciprocal field transformation not only extends the framework of the transformation theory for nonreciprocal wave manipulation but also holds great potential in applications such as ultrasensitive sensors and nonreciprocal communication.
场变换作为变换光学的一种扩展，为非互易波操纵提供了一种独特的手段，然而实验实现仍然是一个巨大的挑战，因为它需要超材料具有严格的材料参数，例如纯非互易双各向异性参数。在此，我们在二维声学系统中开发并演示了一种非互易场变换，使用一种有源超表面，它可以独立控制所有本构参数并实现纯非互易威利斯耦合。场变换超表面能够实现定制的场分布操纵，以预定比例实现局部场放大。该超表面展示了对各种激励条件的自适应能力，并且可以扩展到其他几何形状。该超表面还实现了内部和外部激励的非互易波传播，展示了一种单向声学器件。非互易场变换不仅扩展了非互易波操纵的变换理论框架，而且在超灵敏传感器和非互易通信等应用中具有巨大潜力。
