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Boosting Optical Nanocavity Coupling by Retardation Matching to Dark Modes
preprintposted on 2023-01-10, 03:04 authored by Rohit Chikkaraddy, Junyang Huang, Dean Kos, Eoin Elliott, Marlous Kamp, Chenyang Guo, Jeremy J. Baumberg, Bart de Nijs
Plasmonic nano-antennas can focus light to nanometre length-scales providing intense field enhancements. For the tightest optical confinements (0.5-5 nm) achieved in plasmonic gaps, the gap spacing, refractive index, and facet width play a dominant role in determining the optical properties making tuning through antenna shape challenging. We show here that controlling the surrounding refractive index instead allows both efficient frequency tuning and enhanced in/output-coupling through retardation matching as this allows dark modes to become optically active, improving widespread functionalities.