Am. Andriesh et al., THE MECHANISM OF ENHANCEMENT OF PHOTOINDUCED ABSORPTION IN AS2S3 GLASS AT SUB-BANDGAP ILLUMINATION, Journal of non-crystalline solids, 189(1-2), 1995, pp. 147-153
The dependence of additional optical lasses due to illumination of opt
ical As2S3 glass fibers has been investigated. The qualitative explana
tion of the observed dependence is given based on the model of activat
ion of carriers and their redistribution on localized states in As2S3
glass stimulated by sub-bandgap light h omega(sb)< E(g) at 77 K, which
leads to the value of photoinduced absorption in the material studied
. It was found that subsequent illumination of the samples with sub-ba
ndgap light can not only bleach the previously induced absorption but
it can also produce an enhancement of photoinduced absorption. The mec
hanism of non-monotonic property of the kinetics and transient enhance
ment of photoinduced absorption is discussed. A system of rate equatio
ns which describes the process of excess carrier generation, their tra
pping and redistribution on localized states is proposed. The results
of computer simulation of mathematical solutions obtained from photoin
duced absorption rate equations are in good agreement with experimenta
l results.