THERMAL FIXING OF REFRACTIVE-INDEX GRATINGS IN A PHOTOREFRACTIVE POLYMER

A significant increase in storage time by thermal fixing of photorefra ctive (PR) gratings in a polymeric composite of poly-9-vinycarbazole, tricresyl phosphate. fullerene, and 4-N,N-diethylamino-beta-nitrostyre ne is demonstrated, The fixing of the volume holograms is created by q uasifreezing the orientation of the linearly anisotropic chromophore m olecules. The fixed PR gratings can be easily erased by elevating the sample's temperature to the glass transition temperature of the compos ite. The readout of the thermally fixed first-order grating does not r equire the presence of an external electric field. (C) 1997 American I nstitute of Physics.