Quasi-bound states in the continuum induced by in-plane and out-of-plane asymmetry in all-dielectric metasurfaces

Abstract

In this paper, we propose a periodic structure consisting of a pair of square holes etched through square silicon substrates to achieve a high-Q quasi-BIC resonance peak at 1524 nm. The simulation results indicate that the Q factor of the excited quasi-BIC can reach 12,660. Multipole decomposition and near-field distribution show that the quasi-BIC of the square etched hole structure is primarily dominated by magnetic dipoles, electric quadrupoles, and magnetic quadrupoles. When structural parameters shift in other directions, or when the square hole is rotated or changed to a circle, this quasi-BIC demonstrates good robustness.