Interaction between the magnetic polariton and surface plasmon polariton

This work numerically investigated the interaction between two resonances: the magnetic polariton (MP) and surface plasmon polariton (SPP). A reflectance contour plot of deep silver slit arrays quantitatively identified the MP mode and the SPP excitation's dependence on the period. Five arrays were selected for their SPP excitation wavenumber that approached and then diverged from that of an MP mode. Reflectance spectra from arrays showed dips associated with the two resonances between 10,000 cm−1 and 25,000 cm−1. Both the magnitude and corresponding wavenumber of nearby dips were modified by the interaction. Moreover, a third dip might appear or two dips might merge into a wider valley when two resonance excitation wavenumbers are close enough. The interaction was further elucidated with electromagnetic fields, Poynting vectors, and the energy density corresponding to representative reflectance dips.