Formation of a grating of submicron nematic layers by photopolymerization of nematic-containing mixtures

A submicron, spatially periodic, structure consisting of a sequence of oriented layers of a nematic liquid crystal (NLC), separated by isotropic polymeric walls, was obtained experimentally. This was accomplished by polymerization induced by the interference pattern of UV laser radiation in a NLC-containing prepolymer mixture. It was established that such a structure occurs when phase separation and nematic ordering are prevented during the polymerization process. These structures are the diffraction elements, whose efficiency is much greater than that of a standard grating of polymer-dispersed liquid crystals [1-4] which is obtained in the same initial mixture. Specifically, a diffraction efficiency of 60-70% was obtained for structures with the period Lambda = 0.2 mum, even in mixtures where a grating with Lambda < 6 mum cannot be obtained at all by the standard technique.