Photoinduced molecular reorientation in polymers, Langmuir-Blodgett films and liquid crystals

A review of the experimental data on a photoinduced molecular reorientation in various molecular guest-host systems (dyes in liquid solutions, liquid crystals and polymer matrices), side-chain polymers and Langmuir-Blodgett films (LBFs) containing light absorbing chromophores is presented. The photoorientation may be reversible or irreversible. It is accompanied by the photoinduced dichroism and optical anisotropy which is widely used for optical recording information. Special attention is paid to the photoassisted poling of polymers and LBFs, a novel technique that allows for the preparation of the stable photoelectrets at room temperature possessing very promising nonlinear optical properties. The physical mechanisms of the photoinduced molecular reorientation are discussed.