Light-induced light absorption changes in AsSe and GeSe2 thin films

Reversible transmittance (T) changes for λ = 6328 Å light were observed in stabilized AsSe and GeSe₂ thin films when irradiated by λ = 5145 Å and λ = 4880 Å wavelength exciting light pulses. During photodarkening, T reaches a steady state value obeying a T ∝ t^-1 relationship then approaches its starting value exponentially when the light is switched off. Both of these processes develop in a few seconds. The transmittance changes are explained by variations in the absorption coefficients with temperature, controlled by the absorption and loss of energy.