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 bandedge 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/cm(2) Above this value, departure from linearity is observed. For a pump intensity of 3 GW/cm(2), the band shifts by 11 meV. The response of the shift tracks the profile of the pumping pulse. (C) 1996 American Institute of Physics.6881093109
