An All-Dielectric Metasurface Building Block for the Kerker Effect between Excitons and Nanocavities: Germanium Nanogroove

摘要

Coupling between light and matter has many infusive physical effects andrnpotential applications. Large Rabi splitting energy is achieved in manyrnplasmonic nanostructures; however, these noble metallic materials generallyrnsuffer from a high level of Joule heating losses at optical frequencies.rnAs an alternative strategy, all-dielectric materials for manipulating light atrnthe subwavelength scale have attracted enormous interest. However, thernunderstanding of the interactions between all-dielectric nanostructures andrnmolecular excitons remains limited to date. Here, the use of a germaniumrnnanogroove as a new all-dielectric metasurface building block is demonstratedrnfor the Kerker effect between molecular excitons and nanocavities. Arndistinct dip in the backward scattering spectra is observed, indicating relativelyrnstrong light–matter interaction due to the cavity magnetic resonancernmode in the grooves. Germanium with a large real part and nonnegligiblernimaginary part of the refractive index in the visible region provides magneticrnfield enhancement similar to that of other all-dielectric nanostructures; thisrnphenomenon is theoretically explained by simulating the magnetic field distributionrnin the grooves. These findings may help researchers to better understandrnthe interactions between all-dielectric nanostructures and molecularrnexcitons and indicate that germanium nanogrooves can potentially be usedrnas metasurface building blocks in nanophotonic devices.