Magnetic building-block-type metasurfaces for tunable elastic-wave manipulations of higher-order diffractions

Abstract

Most elastic metasurfaces face the limitation of their passive design, which results in efficacy only in a narrow frequency band and single structural function. Moreover, as an inherent phenomenon, the manipulations of higher-order diffractions are normally absent in the existing tunable elastic metasurfaces. Realization of an efficient, compact tunable metasurface design with more tunable degrees of freedom for elastic-wave control, especially for higher-order diffraction modes, remains a challenge. Here, a design strategy to address the challenges associated with low or non-tunable degrees of freedom in elastic metasurfaces is demonstrated. The proposed metasurface framework utilizes magnetic-building-blocks to achieve high degrees of freedom and enables tunable elastic-wave control of higher-order diffractions. An equivalent model is established to theoretically present the transmittance profiles with frequency and building-block height. A variety of tunable scenarios, including the anomalous refractions, controllable higher-order diffraction modes, switchable asymmetric propagation, and digitally programmable vibration-isolation et al, are numerically and experimentally evaluated. This design serves as an enriched strategy to enable tunable vibration and wave steering.