Hyper-Rayleigh scattering by inhomogeneous thin films of Pb_x(Zr_0.53Ti_0.47)O₃: Disorder effects

The hyper-Rayleigh scattering technique is used for experimental study of thin polycrystalline films with in-plane structural disorder undetectable with linear-optical methods. A significant influence of this disorder on hyper-Rayleigh scattering indicatrices is observed. The shift of the indicatrix maximum relative to the specular direction reveals anticorrelations in the spatial distribution of inhomogeneities in the bulk of the films. By contrast, the shape of Rayleigh (linear) scattering indicatrices is found to be driven by the film surface roughness. A hyper-Rayleigh analog of speckle patterns is detected at small values of the laser spot size. Theoretical results obtained for simple stochastic models of the film structure and surface roughness are in good agreement with the experimental data.