Controlling the interaction between localized and delocalized surface plasmon modes: Experiment and numerical calculations

We study the fundamental optical effects originating from the resonant excitation of localized and delocalized surface plasmon modes supported by a multilayer metallic photonic crystal slab. The optimized model system consists of a periodic gold nanowire array and a spatially separated homogeneous silver film. We show that the spacer layer controlled dipole-surface interaction reveals a pronounced period dependence when an ordered nanowire arrangement is employed. Our analysis demonstrates that strong coupling gives rise to the formation of hybridized plasmon modes. Moreover, the magnetic activity of the metallic multilayer structure is theoretically analyzed. The presented effects provide interesting tools for the optimization of future plasmonic nanodevices and metal-based metamaterials.