Dual Control of Enhanced Quasi-Bound States in the Continuum Emission from Resonant c-Si Metasurfaces

Opticalbound states in the continuum (BICs) offer strong interactionswith quantum emitters and have been extensively studied for manipulatingspontaneous emission, lasing, and polariton Bose-Einstein condensation.However, the out-coupling efficiency of quasi-BIC emission, crucialfor practical light-emitting devices, has received less attention.Here, we report an adaptable approach for enhancing quasi-BIC emissionfrom a resonant monocrystalline silicon (c-Si) metasurface throughlattice and multipolar engineering. We identify dual-BICs originatingfrom electric quadrupoles (EQ) and out-of-plane magnetic dipoles,with EQ quasi-BICs exhibiting concentrated near-fields near the c-Sinanodisks. The enhanced fractional radiative local density of statesof EQ quasi-BICs overlaps spatially with the emitters, promoting efficientout-coupling. Furthermore, coupling the EQ quasi-BICs with Rayleighanomalies enhances directional emission intensity, and we observeinherent opposite topological charges in the multipolarly controlleddual-BICs. These findings provide valuable insights for developingefficient nanophotonic devices based on quasi-BICs.

Automated summary

In this study, we enhance the emission of quasi-bound states in the continuum (quasi-BIC) from a resonant monocrystalline silicon (c-Si) metasurface through lattice and multipolar engineering. We identify dual-BICs originating from electric quadrupoles (EQ) and out-of-plane magnetic dipoles, with EQ quasi-BICs exhibiting concentrated near-fields near the c-Si nanodisks. The enhanced radiative local density of states of EQ quasi-BICs overlaps spatially with the emitters, promoting efficient out-coupling.