Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708, USA.
College of Physics, Optoelectronics and Energy, Soochow University, 1 Shizi Street, Suzhou 215006, China.
Nat Commun. 2014 Nov 24;5:5553. doi: 10.1038/ncomms6553.
Metasurfaces are a family of novel wavefront-shaping devices with planar profile and subwavelength thickness. Acoustic metasurfaces with ultralow profile yet extraordinary wave manipulating properties would be highly desirable for improving the performance of many acoustic wave-based applications. However, designing acoustic metasurfaces with similar functionality to their electromagnetic counterparts remains challenging with traditional metamaterial design approaches. Here we present a design and realization of an acoustic metasurface based on tapered labyrinthine metamaterials. The demonstrated metasurface can not only steer an acoustic beam as expected from the generalized Snell's law, but also exhibits various unique properties such as conversion from propagating wave to surface mode, extraordinary beam-steering and apparent negative refraction through higher-order diffraction. Such designer acoustic metasurfaces provide a new design methodology for acoustic signal modulation devices and may be useful for applications such as acoustic imaging, beam steering, ultrasound lens design and acoustic surface wave-based applications.
超构表面是一类具有平面轮廓和亚波长厚度的新型波前整形器件。对于提高许多基于声波的应用的性能而言,具有超低轮廓但具有非凡波操控特性的声超构表面是非常需要的。然而,使用传统的超材料设计方法来设计具有类似功能的声超构表面仍然具有挑战性。在这里,我们提出了一种基于锥形迷宫超材料的声超构表面的设计和实现。所展示的超构表面不仅可以根据广义斯涅尔定律来引导声束,而且还表现出各种独特的特性,例如从传播波到表面模式的转换、非凡的波束转向以及通过高阶衍射实现的明显负折射。这种设计的声超构表面为声波调制器件提供了一种新的设计方法,可能在声成像、波束转向、超声透镜设计和基于声波表面波的应用等领域有应用价值。