Experimental observation of percolation-enhanced nonlinear light scattering from semicontinuous metal films

Summary form only given. In random metal-dielectric films where the metal coverage of the dielectric substrate is close to the percolation threshold, disorder-induced localization of plasmons occurs, resulting in huge fluctuations of local fields. One of the most interesting, theoretical predictions for such percolation films is that nonlinear light scattering at the nth frequency harmonic n/spl omega/ of an incident beam can be significantly enhanced and is characterized by a broad, nearly isotropic angular distribution. According to theory, this effect, which was denoted in as percolation-enhanced nonlinear scattering (PENS), is caused by the huge local-field fluctuations associated with the localized plasmons. Here we experimentally verify the existence of the PENS effect by measurements of the second harmonic generation from semicontinuous and continuous gold films.