Probing of spatial orientational correlations between chromophores in polymer films by femtosecond hyper-Rayleigh scatterring

Femtosecond hyper-Rayleigh scattering has been used to probe the spatial orientational fluctuations between nonlinear optical chromophores as dopants in spincoated polymer films. The fluctuation in the second-order incoherently scattered light intensity upon micro-translating the solid sample is indicative of the degree of spatial correlation between the individual chromophores. The decay of the autocorrelation function of this fluctuating signal is characterized by a spatial correlation length. Electric-field poling of dipolar chromophores is shown to increase this correlation length. The longer correlation length after poling results from a higher degree of spatial orientational correlation between the individual chromophores.