MEAN-FIELD THEORY OF OPTICAL STORAGE IN LIQUID-CRYSTALLINE SIDE-CHAINPOLYMERS

Liquid crystalline side-chain polymers are very promising materials fo r optical storage due to the high long-term stability (several years) and the large values of photoinduced anisotropy (Delta n approximate t o 0.1). In this paper a simple mean-field theory of the storage proces s is presented and compared to experiments for azobenzene polyesters. The multi-domain structure of the polymer material is taken into accou nt and inter-molecular interactions are described using a Maier-Saupe mean-field theory. We demonstrate how the mean-field model combined wi th a molecular reorientation mechanism based on photoinduced trans <-- > cis isomerization provides an explanation for the stability as well as the intensity dependence of the photoinduced anisotropy. A detailed comparison with experimental observations shows an excellent agreemen t over the entire range of intensities, (C) 1998 Elsevier Science B,V.