Combined Photonic-Plasmonic Modes Inside Photonic Crystal Cavities

In this article, we present a numerical study of the optical properties of a metal nanowire interacting with a localized cavity in a 2D photonic crystal. The nature of the modes, their wavelength and width are investigated as a function of the nanowire’s radius. It is shown in particular that a nanowire with diameter about the lattice constant presents very narrow resonances corresponding to hybrid photonic-plasmonic modes, where increased lifetime is attributed to the decrease of the radiative losses by interaction with the photonic crystal. These results open interesting applications in areas where narrow plasmonic resonances are required, as in localized surface plasmon (LSP) resonance-based biosensing.