A Bound State in the Continuum Supported by a Trimeric Metallic Metasurface

A bound state in the continuum (BIC) is a localized continuous spectrum of radiating waves. In this study, coupled-mode theory introduced to more precisely interpret symmetry-protected BIC and quasi-BIC facile trimeric metasurface, compared with Fano formula, which generate high-quality factor resonance metallic slit metasurface. The multipole decomposition method near field distribution structure further illustrate that underlying physics high-Q mainly originated from interference between electric quadrupole mode magnetic toroidal mode. Physical mechanism shows arises perturbation BICs. result may play role applications lasers, optical sensors, low-loss fibers.