Surface and volume gratings investigated by the moving grating technique in sol-gel materials

We analyze the various contributions to optically induced gratings in an azo-hybrid sol-gel material. This is done by a time-resolved grating translation technique, by polarization and laser intensity dependent experiments, and by index matching with an oil film. We characterize surface relief and anisotropy (index and absorption) gratings. In particular, we measure the phase shift of the surface relief modulation with respect to the fringe interference pattern.