Instabilities induced by Light in Liquid Crystal Cells with a Photo-Responsive Substrate

Instabilities are discussed which take place when a nematic liquid crystal (LC) layer, enclosed between a planar reference plate and a photosensitive substrate, is illuminated with polarized light from the reference side ({\it reverse} geometry). The dependence of the observed effects on the wavelength, polarization direction of the light, and on the thickness of the LC layer is explained by a model based on photoinduced surface torque. The application possibilities of the phenomena are also explored.