SPECTRAL CHANGE OF FEMTOSECOND PULSES DUE TO INDUCED AMPLITUDE AND PHASE MODULATIONS

Pump-probe spectroscopy of amorphous semiconductor and glass samples was performed. The spectral shift of a continuum probe because of induced phase modulation was observed when the continuum had a sharp peak in the spectrum. When a fundamental pulse was used for the probe, oscillatory structures in the difference transmission spectra were observed for both negative and positive time delays. This behavior can be reproduced by a numerical simulation with the assumption of induced amplitude and phase modulations of the probe pulse. Both the real and the imaginary parts of chi(3) were simultaneously estimated from the modulations.