Frequency‐Coded Passive Multifunctional Elastic Metasurfaces
Junjie Rong, Wenjing Ye, Shengyuan Zhang, Yijun Liu
Abstract
Abstract As an emerging material, metasurfaces open the door to a wide range of applications based on ultrasonic and elastic waves. However, most of the existing elastic metasurfaces have a fixed functionality and operate at a fixed frequency, which make them difficult to adapt to changing working requirements and/or environments. Although several recently proposed reconfigurable designs can relax this limitation, they either need laborious tuning or complex active control systems. In this work, by encoding multiple functionalities onto a single metasurface through operation frequencies, passive metasurfaces with switchable multifunctionalities are proposed and realized. Different wave manipulation functions of a single metasurface can be switched from one to another simply by changing the operation frequency. The design of these metasurfaces is realized using a systematic design approach based on topology optimization. Frequency‐coded multiple elastic wave manipulation functions, including wave beam steering and focusing, are numerically and experimentally demonstrated. Good agreement between the numerical simulations and experimental measurements is achieved. The proposed design strategy significantly enhances the functionalities and adaptivity of metasurfaces, moving them closer towards real‐world applications.