Nonlinear Optical Properties of Polyelectrolyte Thin Films Containing Gold Nanoparticles Investigated by Wavelength Dispersive Femtosecond Degenerate Four Wave Mixing (DFWM)

The nonlinear optical (NLO) properties of gold nanoparticles embedded in polyelectrolyte multilayer thin films, in particular the dispersion of the third-order nonlinearity and its relaxation around the plasmon band, have been investigated by femtosecond wavelength dispersive degenerate four wave mixing. The experimental results are discussed in terms of a simple model for the third-order optical nonlinearity of nanoparticle systems. The results demonstrate that not only is the color of metallic nanoparticles dominated by surface plasmon optical resonance but surface plasmons govern NLO phenomena as well.