Polarization‐Independent Quasibound States in the Continuum

Abstract

A new property of the trapped mode (bound state in the continuum, BIC) supported by a dielectric resonant metasurface, which changes its lattice symmetry, is uncovered. The transformation of a metasurface composed of identical nanodisk resonators into a ?diatomic? structure when one half of the nanodisks change their diameters is studied. The resulting folding of the Brillouin zone in the k-space transforms the trapped (BIC) mode to quasi-BIC resonances manifested in the polarization-independent response. This novel feature is verified experimentally in the transmission of the metasurfaces illuminated by light with both linear and circular polarizations.