Orientational holographic grating observed in liquid crystals sandwiched with photoconductive polymer films

We presented a novel type of orientational photorefractive device, consisting of liquid crystals (LCs) sandwiched with photoconductive polymer films across the insulated polymer films. The photoexcited charges were generated in the photoconductive layers and eventually become trapped in the dark areas at the insulated polymer surfaces. The resulting space charge field reoriented the LC molecules and the holographic gratings were generated. The strong beam coupling effects were observed and the refractive index modulation Δn was estimated to be of the order of 3.6×10−3.