Holographic grating recording in large area photoconducting liquid crystal panels

Large area (50 cm2) liquid crystal panels for optical information processing are evaluated. Optically-controlled diffraction gratings are reported in a dye-doped nematic confined between two transparent electrodes and SiO2 insulating layers. The electrodes are coated with unidirectionally treated alignment layers in order to form a 90° twisted nematic structure. The parameters of the phase gratings obtained in a two-wave mixing experiment and light diffraction are controlled by applied voltage. The role of insulating layers is studied in respect of device performance and response time.