A simple phenomenological study of photodarkening in As2S3 glasses

Abstract By using a simple photodarkening model we investigate the dynamics of photodarkening in As 2 S 3 glasses under laser illumination. We find that, for illumination at 633 nm, the quantum efficiency of the photodarkening process is of about 4% and that the absorption cross-section of the dark centers is ∼2.2 times larger than that of the intrinsic structural units. The insights gained from the modeling are compared with the experimental results obtained when writing Bragg gratings using 633 nm, 594 nm and 568 nm laser light.