Locally Resonant Metagrating by Elastic Impedance Modulation

Optical and acoustic metagratings have addressed the challenges of low-efficiency wave manipulation and high-complexity fabrication associated with metamaterials and metasurfaces. In this research, the concept of locally resonant elastic metagrating (LREM) is both theoretically and experimentally demonstrated, which is underpinned by the unique elastic impedance modulation and the hybridization of intrinsic evanescent waves. Remarkably, the LREM overcomes the size limitations of conventional metagratings and offers a distinctive design paradigm for highly efficient, compact, and lightweight structures for wave manipulation in elastic wave systems. Importantly, the LREM tackles a key challenge inherent to all elastic wave-manipulation metastructures, which consists in the unavoidable vibration modes in finite structures hindering their real-world applications.