Appearance and reorientation of photoinduced anisotropy in chalcogenide glassy films

The kinetics of appearance and reorientation of photoinduced dichroism (a manifestation of photoinduced anisotropy) is studied in chalcogenide glassy films by means of the polarization modulation technique. Two distinct processes are identified: creation of photoinduced defects and photo-stimulated orientation of defects both native and photoinduced. Of these processes, the first one can be carried out by both unpolarized and polarized radiation and has much larger time constant than the second. The annealing temperatures of the two effects are also different. In all of materials studied (AsSe, Ge₂Pb₁S₄, Se) the effect of photoinduced anisotropy was shown to be a one-photon process. Unusual behavior of dichroism in partially crystallized Se films is revealed.