Quasi-Bound States in the Continuum for Acoustic and Elastic Waves
We study the localization of flexural and acoustic waves in metasurfaces by means of clusters of scatterers. We show that when the scatterers are placed regularly in the perimeter of a circumference the structure forms a resonator which quality factor grows up exponentially with the number of scatterers. This allows the realization of high-quality resonant cavities whose quality factor can be easily tailored and, consequently, its interaction with the continuum. These modes, also named quasi-bound states in the continuum or QBICs, are robust against small perturbations in the geometry of the cluster, being therefore an excellent platform for the design of efficient structures for wave-trapping devices. Numerical experiments are performed for elastic waves in thin elastic plates and acoustic waves trapped atop a metasurface, and an experimental validation of the latter is also presented.
