Hybrid states of propagating and localized surface plasmons at silver core/silica shell nanocubes on a thin silver layer

Hybrid characteristics of propagating surface plasmons (PSPs) and localized surface plasmons (LSPs) appear at a combined structure of a thin silver (Ag) layer and silver core/silica shell nanocubes (AgNC@SiO₂s) in the Kretschmann configuration, because the resonant condition of PSPs on the thin Ag layer is significantly modified by LSPs of the AgNC@SiO₂s. We investigate theoretically and experimentally that due to the hybrid property, the slope and position of the minimum reflectance band can be controlled on a graph of incident angle versus wavelength of reflected light, by changing structural parameters. The hybrid properties of PSPs and LSPs have a potential to simultaneously detect surface plasmon resonance signals and fluorescence images.