Enhancement of exciton emission in WS2 based on the Kerker effect from the mode engineering of individual Si nanostripes†
Coupling between nanostructures and excitons has attracted great attention for potential applications in quantum information technology. Compared with plasmonic platforms, all-dielectric nanostructures with Mie resonances are more practical because of low-loss, low-cost and CMOS compatibility. However, weak field enhancements in single element dielectric nanostructures hinder their applications in both strong and weak coupling regimes. The Kerker effect arising from the far-field electro-magnetic interactions in dielectric nanostructures brings a new mechanism to realize effective coupling with excitons. Until now, it still remains unsolved whether effective Mie-exciton coupling can be realized based on pure far-field Kerker effect. Therefore, we proposed a silicon-on-insulator (SOI) integrated Mie resonator with a 135 nm top oxide layer to exclude the near-field coupling between excitons and silicon (Si) nanostripes. Through tuning the widths of Si nanostripes to obtain highly directional photoluminescence (PL) emission under Kerker conditions, strong PL enhancements can be observed, whose enhancement factors are comparable to the reported best performances of single all-dielectric or even plasmonic nanostructures coupling with 2D excitons. Our findings bring new strategies for strong light–matter interactions with near-zero heating loss and make it possible to construct 2D materials–silicon hybrid integration for future nanophotonic and optoelectronic devices.