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.