Dynamics of grating formation in photorefractive sol-gel composites

We prepared the photorefractive composite based on organic-inorganic hybrid materials containing a charge transporting molecules, second-order nonlinear optical chromophore, photosensitizer, and plasticizer either as a side chain unit or a guest molecule. Carbazole group and 2-{4-[(2-hydroxy-ethyl)-methyl-amino]-benzylidene}-malononitrile were reacted to isocyanatotriethoxysilane to provide the functional precursor molecules. 2,4,7-Trinitrofluorenone was added into the sol-gel materials to induce a charge transfer complex. We also could select the plasticizer that is well miscible with the matrix molecules. Strong hydrogen bond between the molecules was quite effective to control the optical quality of the resultant matrix. We also compared the dynamic properties of the diffraction efficiency in the sol-gel sample with the change of the concentration of each component.