Photoinduced generation and reorientation of linear dichroism in AsSe glassy films

The kinetics of linear dichroism generation and reorientation in glassy AsSe films induced by linearly polarized He-Ne laser light of different intensities is studied by means of a polarization-modulation technique. Two distinct processes are identified: creation of photoinduced defects and their photostimulated orientation and reorientation. The first process can be carried out by both unpolarized and polarized light and has a much larger time constant than the second one. The annealing temperatures of the two effects are also shown to be different. Comparison of restoration of the initial dichroism-generation kinetics after annealing with the photodarkened AsSe film thermobleaching leads to a conclusion about certain identity of the defects responsible for the photodarkening and photoinduced anisotropy phenomena. Tikhomirov and Elliott's model of photoinduced anisotropy in chalcogenide glasses is further developed.