Selective Perturbation of Eigenfield Enables High-Q Quasi-Bound States in the Continuum in Dielectric Metasurfaces

Abstract

Dielectric metasurfaces supporting symmetry-protected bound states in the continuum (SP-BICs) have emerged as an attractive platform for manipulating light−matter interactions on the nanoscale. However, quasi-BIC with a high quality factor (Q-factor) by releasing SP-BIC is still a challenge in practice due to the Q-factor sensitivity to asymmetric parameters and the limited level of fabrication. Here, we present a universal perspective aiming at achieving high-Q-factor quasi-BICs through the efficient perturbation of eigenfields. This approach affords the flexibility to select scaling laws of the Qfactor, and a larger Q-factor can be obtained under the disturbance of the weak field region for the same asymmetric parameters. Such findings have been extended to classical nanostructures, such as dimeric nanobars, splitting rings, and nanodisks. Finally, square nanodisks embedded with air holes at different positions are used as an example to experimentally confirm our findings. Our method provides a new idea for the release of high-Q-factor quasi-BICs and paves the way for the realization of high-performance optical devices based on a high Q-factor.