title: Dispersion relations for coupled surface plasmon-polariton modes excited in multilayer structures.
abstract: The coupled surface plasmon-polariton (SPP) modes excited in an Al/SiO2/Al multilayer structure were analyzed using angle-resolved electron energy-loss spectroscopy (AREELS) with a relativistic electron probe. The dispersion relations for the coupled SPP modes were then directly observed and compared with predicted relations obtained via calculations. Good agreement was noted between the experimental and calculated results. In the multilayer structures, the dispersion relation for the coupled SPP modes was found to be sensitive to the thickness of each film, which could be interpreted qualitatively by the electron energy-loss probability calculated for thin aluminum (Al) films and narrow Al gaps using Kröger's formula. It was demonstrated that significant differences in the excitation probability for SPPs could be observed depending on the coupling modes.
authors.affiliation: Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: Hikaru
authors.initials: H
authors.lastname: Saito
authors.forename: Kyoko
authors.initials: K
authors.lastname: Namura
authors.forename: Motofumi
authors.initials: M
authors.lastname: Suzuki
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kurata
keywords: coupled mode; dispersion relation; electron energy-loss spectroscopy; multilayer; surface plasmon-polariton; waveguide