Modeling of Evolution of Diffraction Patterns from Light-Induced Gratings in AgCl-Ag Waveguide Films

For the first time calculations have been performed to model evolution of small-angle scattering and diffraction patterns under action of a focused linearly polarized laser beam (650 nm, 25 mW) normally illuminating an AgCl-Ag waveguide film on glass substrate. Calculated patterns obtained for the film thickness of 100 nm are similar to experimental ones both in statics and in dynamics. This is a confirmation of validity of current ideas concerning the mechanism of development of induced diffraction gratings in AgCl-Ag film. Adjustment of grating parameters in the course of modeling, while focusing on the pattern appearance as a whole, provided new information on properties and parameters of the gratings. The main result is a proof of inherent domain nature of the aggregate of gratings. The proposed modeling is a new tool for analysis of experimental results on diffraction grating development in waveguide films.