V. Cimrova, D. Neher, R. Hildebrandt, M. Hegelich, A. von der Lieth, G. Marowsky, R. Hagen, S. Kostromine, T. Bieringer
Comparison of the birefringence in an azobenzene-side-chain copolymer induced by pulsed and continuous-wave irradiation.
Applied Physics Letters.  81(7), 1228-1230  (2002)

A comparative study of photoinduced birefringence in azobenzene-side-chain copolymers under continuous-wave (cw) and pulsed irradiation is presented. Absolute refractive index changes were determined by the attenuated total reflection spectroscopy. We clearly demonstrated that pulsed, similarly to cw, irradiation induces a three-dimensional reorientation of azobenzene chromophores. For the same light dose, pulsed irradiation using ns pulses of appropriate pulse energy led to higher values of birefringence, which can be attributed to a cooperative motion of azobenzene side chains and thermal effects induced by the laser pulses. (C) 2002 American Institute of Physics.