PHOTOCHEMICALLY FORMED REFRACTIVE-INDEX PROFILES IN NONLINEAR-OPTICAL POLYMER THIN-FILMS

A simple but realistic kinetic model has been developed to describe the refractive index profile formed by photochemical reaction in nonlinear optical polymers. The effects of the absorption due to the unconvertible reactant and the photoproduct are included in the model. The experimental results are consistent with the model. The parameters required in the model are obtained from a simple transmission experiment. The rate of the bleached depth change with time becomes slower as the bleaching proceeds, while the shape of the index profile was kept nearly the same. Small absorption of bleaching light due to the photoproduct has a significant effect on the resulting refractive index profiles.