Photoabsorption and photorefraction in glassy As2Se3 films under pulsed excitation

Time-resolved photoabsorption (PA) and photorefraction (PR) in glassy As 2 Se 3 films were investigated under pulsed excitation above the optical threshold. At a pumping power of 300 W/cm 2 considerable relative changes of the absorption coefficient (Δα/α) and refractive index (Δn/n) were found to occur in the transparency region. Investigation of the PA decay kinetics in the context of the multiple trapping model and the Kramers-Kronig analysis of the PR data permit us to identify the revealed large optical nonlinearity with the filling of localized states.