Mean-Field Theory of Photoinduced Molecular Reorientation in Azobenzene Liquid Crystalline Side-Chain Polymers

A novel mean-field theory of photoinduced reorientation and optical anisotropy in liquid crystalline side-chain polymers is presented and compared with experiments. The reorientation mechanism is based on photoinduced $\mathrm{trans}\leftrightarrow \mathrm{cis}$ isomerization and a multidomain model of the material is introduced. The theory provides an explanation for the high long-term stability of the photoinduced anisotropy as well as a theoretical prediction of the temporal behavior of photoinduced birefringence. The theoretical results agree favorably with measurements in the entire range of writing intensities used experimentally.