Photodarkening in Ge3Se17 glass

In this paper, we present measurements of the kinetics of photodarkening in Ge3Se17 glass. The photodarkening is induced with sub-bandgap light and ob served as transmission changes through a 1 mm thick sample of the glass. Bo th transient nonlinear and permanent processes are detected with these meas urements. We consider the Various sources that could lead to changes in sam ple optical properties and suggest that changes in electronic structure are the most reasonable explanation for the observed photodarkening. Compariso n of the results with a model of light induced changes in amorphous seleniu m leads to an explanation for these effects based on the formation of dynam ical bonds during illumination. (C) 2000 Elsevier Science B.V. All rights r eserved.