Nonlinear-optical liquid crystal cells based on microstructured substrates

The nonlinear optical response is detected in hybrid liquid crystal (LC) cells, which are fabricated by using nonuniform substrates, namely photonic crystals with periodic microstructures etching on Si plates. The main nonlinear mechanism exploited in the hybrid LC cells was the orientation nonlinearity in bulk pure nematic 5CB due to surface induced photorefractive effect. The effective Kerr nonlinear susceptibility is determined from the two-wave mixing experiment, for which we develop the model to calculation of the diffraction efficiency. The model consider the self-diffraction of waves in the Raman-Nath regime and covers the case of large diffraction efficiency, when the conventional approximation formula is not valid. The model also takes into account big losses of the light on the absorption and/or on the scattering in a thin layer, such it happens in the hybrid LC cells owing to scattering and formation of light periodic pattern.