Ultra-broadband passive acoustic metasurface for wide-angle carpet cloaking

• Main Authors: Hong-Tao Zhou, Wen-Xiao Fu, Yan-Feng Wang, Yue-Sheng Wang, Vincent Laude, Chuanzeng Zhang
• Format: Article
• Language: English
• Published: Elsevier 2021-02-01
• Series: Materials & Design
• Subjects: Acoustic metasurfaces; Carpet cloaking; Ultra-broad bandwidth; Wide angle; Inverse optimization design
• Online Access: http://www.sciencedirect.com/science/article/pii/S0264127520309503

Acoustic metasurfaces can reshape a reflected wavefront rather arbitrarily, despite being much thinner than the wavelength, thus allowing on-demand wavefront modulation in a variety of applications. Recent passive metasurfaces, however, have suffered from bandwidth limitations, thus restricting their range of operation. In this work, we propose the systematic design of ultra-broadband passive metasurfaces by combining the broadband local reflection rule with an optimization method. The validation of the technique is demonstrated by fabrication and measurement of an ultra-broadband carpet cloak. Numerical and experimental results show that the relative bandwidth of the optimized carpet cloak, thinner than one fifth of the maximum wavelength, can exceed 93.33%, a value that is much larger than that of previous passive metasurfaces. Furthermore, multi-frequency pulse incidence tests reveal the excellent time-domain broadband characteristics of the metasurface over a wide range of angles of incidence. The proposed strategy opens a new route for the design of advanced passive metasurfaces for ultra-broadband wave manipulation and thus promotes practical applications of broadband acoustical devices.