Generation of Multiple Plasmon Resonances in a Nanochannel

In this paper, we investigate the coupling of surface plasmon based on Kretschmann configuration (KC) to localized and delocalized surface plasmon modes supported by metallic nanowire grating (MG) at the oblique incidence. The designed structure consists of MG deposited on a substrate positioned upside down above a conventional KC at a certain distance. Mode coupling and resonant interactions between KC and MG create two new hybrid plasmon modes with narrow bandwidths and unique spectra features, resulting in two obvious dips in the reflection spectrum. Although both dips respond nonlinearly to the refractive index (RI) of the dielectric layer, surprisingly, the sum of two resonance wavelengths has a good linear approximation in a wider RI range. The simultaneous measurement of two resonance dips makes it more attractive as a surface plasmon resonance analysis technology, which is valuable for high-sensitivity optical sensors.