Characterization of Plasmonic Materials by CL
Abstract: A surface plasmon polariton (SPP) is a transverse magnetic (TM) mode electromagnetic wave propagating at a metal/dielectric interface, which is evanescently confined in the perpendicular direction. Metallic surfaces with periodic structures on a sub-wavelength scale have recently been called “plasmonic crystals (PlCs)” in the developing field of plasmonics. We investigate the properties of SPP in plasmonic crystals by using cathodoluminescence (CL) technique combined with a 200 keV scanning transmission electron microscope (STEM). The SPPs excited by high energy electrons are converted to light when propagating on PlCs. Angle resolved spectral measurement of the emitted light enables us to deduce a dispersion pattern of SPP on PlCs, and a beam scan spectral image reveals a standing SPP wave of the band edge state. Size dependence of band gap and symmetry of the standing SPPs were investigated for 1D and 2D PlCs with changing shape parameters.
Key words: cathodoluminescence, surface plasmon, plasmonic crystal, scanning transmission electron microscope