Polarization gratings in photosensitive Langmuir-Blodgett films and chiral liquid crystalline polymers

An investigation was carried out on phase polarization gratings recorded in Langmuir-Blodgett films and chiral liquid crystalline copolymers using two orthogonally circularly polarized Ar-laser beams. All the materials contain ate-benzene chromophores showing photo-induced trans-cis-trans isomerisation. The experimental results are in excellent accordance with the theoretical model based on the Jones matrix representation of the polarization pattern. The Langmuir-Blodgett alms composed of amphiphilic ate-dye molecules manifest an extremely large value of the photo-induced optical anisotropy, Deltan approximate to0.36, stable in time, at least, for half a year. The stability of the photo-induced anisotropy in the liquid crystal polymers studied depends on the molecular structure of the latter.