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We review studies of resonant and nonresonant ultrafast optical processes in semiconductor doped glasses, made at the University of Campinas. First we discuss measurements done in CdTe quantum-dots in glass, excited resonantly. In this case we observe a fast recombination, that depends on the size of the quantum-dot. For the smallest dots, with 3.2 nm average radius, the recovery time constant was found to be 360 fs. Then we describe the observation of the Optical Stark shift in CdSxSe1−x semiconductor-doped glass (SDG) excited under nonresonant below gap condition and probed with femtosecond optical pulses. An ultrafast and pure light-induced shift of the band edge is observed. For a pump intensity of 3 GW/cm2 the band shifts by 11 meV. The response of the shift tracks the profile of the pumping pulse.

A polarization-rotation switch is demonstrated that is based on semiconductor-doped glasses. The response time is shorter than 50 fs, and an on-off ratio of 38:1 could be obtained at a pulse fluence of 1.5 x 10(-6) J/cm(2), which corresponds to an intensity of 10 MW/cm(2).

We report the observation of the optical Stark shift in CdSxSe1−x semiconductor‐doped glass excited under nonresonant below gap condition and probed with femtosecond optical pulses. An ultrafast and pure light‐induced shift of the band edge is observed. The measured dependence of the band edge shift with the pump pulse peak intensity is linear for pump intensities up to 0.3 GW/cm2. Above this value, departure from linearity is observed. For a pump intensity of 3 GW/cm2, the band shifts by 11 meV. The response of the shift tracks the profile of the pumping pulse.

We present femtosecond resolution measurements that demonstrate the occurrence of the ac Stark effect in glass samples doped with CdSSe nanocrystallites. The sample is excited by a 50 fs pulse 80 meV below the band edge. The absorption edge shifts tracking the profile of the pumping pulse. At intensities below 0.5 GW/cm2 the edge shift is linear in the pump intensity. Above this value the shift tends to saturate. We also studied CdTe quantum dots in a glass matrix excited resonantly with the 1S - 1S transition. In this case we observe the dynamics of hole relaxation in the valence band. The hole population equilibrates with a time constant of less than 100 fs.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.