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 at e-hybrid sol-gel material. This is done by a time-resolved grating translat ion technique, by polarization and laser intensity dependent experiments, a nd by index matching with an oil film. We characterize surface relief and a nisotropy (index and absorption) gratings. In particular, we measure the ph ase shift of the surface relief modulation with respect to the fringe inter ference pattern. (C) 2000 Elsevier Science B.V. All rights reserved.