Second-harmonic scattered light from one-dimensional rough thin films

We present the results of a numerical study Of the light scattered from a one-dimensional randomly rough nonlinear thin film. The Rayleigh method is used to investigate the influence of the roughness on the second harmonic generation when a thin film is illuminated by a plane wave. In order to know the limits of validity of the Rayleigh method, the results are compared to the results obtained with a rigorous differential method used for nonlinear gratings. The numerical results exhibit narrow peaks in the angular distribution of the harmonic light scattered from a rough thin film. We show that the peaks are related to the excitation of pump guided waves through the roughness. (C) 1998 Elsevier Science B.V.