Pedersen, Thomas Garm1; Johansen, Per Michael1; Holme, N.C.R.6; Ramanujam, P.S.2; Hvilsted, Søren4
1 Risø National Laboratory for Sustainable Energy, Technical University of Denmark2 Department of Photonics Engineering, Technical University of Denmark3 Optical Microsensors and Micromaterials, Department of Photonics Engineering, Technical University of Denmark4 Department of Chemical and Biochemical Engineering, Technical University of Denmark5 The Danish Polymer Centre, Department of Chemical and Biochemical Engineering, Technical University of Denmark6 Risø National Laboratory
A theoretical framework for the temporal behavior of photoinduced anisotropy in liquid-crystalline azobenzene side-chain polyesters is constructed. The domain structure of the material is taken into account and inter molecular interactions are included through a mean-field description. Photoinduced trans cis isomerization is taken as the dominating source of chromophore reorientation events, and it is demonstrated how this mechanism in conjunction with the multidomain picture is able to account for the long-term stability of the anisotropy. The photoinduced birefringence is calculated by means of a truncated basis method, and in addition the photostationary solution is obtained. Comparison between theory and experiment shows excellent agreement in the entire range of intensities used experimentally.
Optical Society of America. Journal B: Optical Physics, 1998, Vol 15, Issue 3, p. 1120-1129