PHOTODARKENING EFFECT ON ABSORPTION NONLINEARITY IN CDSXSE1-X-DOPED GLASS

We study the influence of laser exposure on transient absorption in a commercial Schott color glass filter doped by CdSxSe1-x microcrystals. With laser exposure the magnitude of the transient absorption at wave lengths above the band gap (negative, with the fast decay rate greater -than-or-equal-to 10(11) s-1), decreases, whereas that at wavelengths below the band gap (positive, decay time of 500 ps) increases (in the spectral interval 600-850 nm) or does not change (at 900-1060 nm). At wavelengths near the band gap the differential absorbance changes in b oth magnitude and sign. A broad maximum between 700-800 nm, which incr eases with photodarkening, has been found in the spectrum of transient absorption. We interpret this maximum as arising from an increase in the number of energy states in the gap. The compatibility of our resul ts with the results published previously is discussed, and a modificat ion of recently proposed models of photodarkening is suggested.