title: Third-order susceptibility of gold for ultrathin layers.
abstract: This Letter presents an experimental study of nonlinear plasmonic effects in gold-stripe waveguides. The optical characterization is performed by a picosecond laser and reveals two nonlinear effects related to propagation of long-range surface plasmon polaritons: nonlinear power transmission of plasmonic modes and spectral broadening of plasmonic modes. The experimental values of the third-order susceptibility of the gold layers are extracted. They exhibit a clear dependence on layer thickness.
authors.forename: Oleg
authors.initials: O
authors.lastname: Lysenko
authors.forename: Morten
authors.initials: M
authors.lastname: Bache
authors.forename: Andrei
authors.initials: A
authors.lastname: Lavrinenko