Holographic grating formation in dye- or fullerene-C₆₀-doped liquid crystals

Nematic crystals (NLC) are characterized by large birefringence that spans a broad spectral range, and large susceptibility to ac, dc, and optical fields. Recently, a nonlinear electro-optical effect in dye- or fullerene C₆₀-doped NCL films was discovered. By theory and experiments, the possibility of using low power lasers of a few milliwatts is demonstrated in conjunction with a small dc field to induce persistent realignment of the liquid crystal director axis, and thus a 'stored' refractive index change in these films. An application of the observed effect is holographic grating generation. In a study, it is shown that gratings can be recorded in these NLC films with a nonlinear sensitivity as high as other materials such as doped glasses or photorefractive crystals.