Optical Nonlinearities and Ultrafast Carrier Dynamics in Semiconductor Doped Glasses

Abstract

The linear and nonlinear optical properties of commercially available CdS_xSe_{1m x} doped glasses are reviewed and the origin, magnitude, and temporal response of the nonlinearities are discussed. The room-temperature carrier dynamics are analysed using femtosecond interband pump-probe measurements. Our experimental results show the evolution of the carriers into a hot, quasi-thermal plasma distribution via electron-electron and electron-phonon scattering. The quasi-thermal distribution cools to the lattice temperature in about 750 fs filling the states just above the band-edge. This band-filling nonlinearity is seen as the bleaching of the absorption above the bandedge. The carrier recombination lifetime is measured to be ; 10 ps at higher carrier densities.