Wide-field polarimetric analysis of photoinduced birefringence in azo-dye-doped thin films: irradiance and time dependence

Research paper by I.-G. Marino, C. Razzetti, P.P. Lottici

Indexed on: 09 Nov '06Published on: 09 Nov '06Published in: Applied Physics B


We have investigated by wide field polariscopy the behaviour of photoinduced birefringence (PIB) in sol–gel hybrid disperse red 1 (DR1) doped films. This technique allows the mapping of the local values of a bell-shaped pump beam irradiance and those of the corresponding photoinduced birefringence. By means of a point-to-point correlation of these maps, we have tracked the dependence of PIB, simultaneously and continuously, on exposure times and pump irradiances. We have then applied some of the available theoretical models, representing birefringence as an analytical function of irradiance and time, to interpolate the experimental PIB data. As compared to the usual PIB measurements, which neglect the spatial distribution of the pump irradiance, our results provide a more detailed and reliable empirical basis on which models of the orientational mechanisms of the photoisomerizable molecules can be developed.