Voltage selectable dual-mode optically-induced grating in ZnTPP doped chiral nematic liquid crystals

Optically-induced grating in ZnTPP doped chiral nematic liquid crystals (CLC) is demonstrated by dual-mode operations, where the dynamic or storage functionality is selected by the amplitude of dc voltage. While the storage can be erased and rewritten by a high dc pulse, it can persist without an electric field, which is the result when the CLC undergoes a switching between a planar and a focal conic state. This tunable dual-functionality grating combines the advantages of bistable storage of CLC and high photosensitivity of dopant, and thus can be potentially exploited in photonic devices to implement different optical information processing in situ.