Light-induced isomerization and photo-orientation in azo and stilbene polymers

The orientational order of amorphous or liquid crystalline polymers with azo or stilbene chromophores can be altered by polarized Light. This photoorientation process is explained by a mechanism based on photoselective trans-cis-isomerization cycles. Monte-Carlo simulations of the process in combination with quantum mechanical calculations show the time-evolution of the photoinduced refractive index change. The different dynamic behaviour of various chromophores which is observed experimentally can be explained by the photochemical properties of the dyes. The application of the materials for optical storage and holographic optical elements is discussed.