Femtosecond and coherent effects in bulk CdSe and CdSexS 1-x doped glasses

Abstract

Bulk CdSe and microcrystallites of CdSexS1- x embedded in a glass matrix are studied using femtosecond laser techniques. The ultrafast dynamics of the photogenerated carriers are measured. Spectral hole burning due to creation of a non-thermal carrier population is observed in both types of materials. The carrier recombination lifetime is measured. Coherent interaction between the probe pulse and the polarization induced in the material as a result of band-to-band excitation by pump pulse is observed. This coherent effect manifests itself as oscillations in the frequency spectrum for very early times when the probe precedes the pump. A semiclassical theory is developed to analyse the observed behaviour. It calculates the transmission spectrum of a weak probe pulse which interacts with the pump-induced polarization of the medium. Qualitative agreement between theory and experiment is obtained