Confinement of Surface Plasmon Polaritons by Heterostructures of Plasmonic Crystals

Square lattice plasmonic crystals (SQ-PlCs) composed of silver pillars generate large bandgaps for surface plasmon polaritons (SPPs). SPP confinement is demonstrated using one- and two-dimensional heterostructures of SQ-PlCs comprised of cylindrical pillars with different diameters in a common square lattice. Two kinds of localized modes are observed to appear in the heterostructures by photon map imaging using cathodoluminescence (CL) technique combined with a scanning transmission electron microscopy (STEM). Angle-resolved CL spectroscopy reveals contrasting characteristics of the two localized modes in their emission distributions, indicating that they originate from the band-edge A and E modes of the matrix SQ-PlC.