Orientational photorefractivity in C 60 -doped liquid crystals injected at nematic phase

Abstract

The optical responses and orientational photorefractives of nematic liquid crystals doped with fullerene were investigated with layer structures in cells. Nematic liquid crystals injected at isotropic phase suffer optical losses due to undesirable light scattering and the switching disorder of liquid crystals under applied voltages, which can lower the photorefractive effects. However, when nematic liquid crystals are injected at a nematic phase, the better cell texture can be obtained due to the flow-induced orientation effect. Sample with this method showed much higher photorefractive effects than that injected at an isotropic phase, because the molecular ordering of liquid crystals highly influences the orientational photorefractive effects. As the temperature at injection state changes, the molecular ordering of liquid crystals may also change. Therefore, through the quantitative analysis of molecular ordering, it was believed that the temperature at an injection state could determine the molecular ordering and in fact, the photorefractive effect.