Strong Purcell effect of magnetic quasi-BICs in the dielectric metasurface

Abstract

Abstract The ultra-strong light field trapped in micro- and nanostructures, and derived from optical bound states in the continuums (BICs), provides a new platform for the facilitation of light–matter interactions. In this work, the spontaneous emission enhancement of quantum emitters using magnetic quasi-BICs metasurfaces is numerically studied. It is found that ultrahigh Purcell factor (PF) ( > 10 5 ) can be easily achieved when the asymmetry parameter decreases. In theory, infinite PF may emerge due to the infinite Q-factor at the BICs. In addition, the PF exhibits a strong dependence on the polarization direction of dipole emitter and the local field distribution in the metasurface. Finally, the photoluminescence enhancement for different perturbation parameters is calculated to confirm strong Purcell effect in the quasi-BICs metasurface. These results show that the magnetic dipole BICs mode holds an enormous potential in manipulating spontaneous emission.