Electrically switchable multiple volume hologram recording in polymer-dispersed liquid-crystal films

Multiple Bragg hologram recording was investigated in trimethylolpropane triacrylate based polymer-dispersed liquid-crystal thin films. Ten volume holograms were stored at a single location of less than 0.8 mm2 area with the diffraction efficiencies of 6%–15%, by a simplified method of peristrophic multiplexing, and the formation process of multiple volume holograms was presented. Furthermore, volume hologram capacity was studied both experimentally and theoretically in this film. Based on the maximum of Δn, ∼2×10−2, the theoretical capacity of a location could be improved to 25 Bragg holograms with the relatively high diffraction efficiency of 1%, and the holographic storage density of more than 20 Gbits/in.2 was achieved just by peristrophic multiplexing. Finally, electrically switchability for multiple holograms with a low threshold voltage of ∼3 V/μm was realized, which demonstrates that this material is a potential medium for electrically controlled holographic storage or diffraction device.