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

Pump-probe spectroscopy of amorphous semiconductor and glass samples w as performed. The spectral shift of a continuum probe because of induc ed phase modulation was observed when the continuum had a sharp peak i n the spectrum. When a fundamental pulse was used for the probe, oscil latory structures in the difference transmission spectra were observed for both negative and positive time delays. This behavior can be repr oduced by a numerical simulation with the assumption of induced amplit ude and phase modulations of the probe pulse. Both the real and the im aginary parts of chi(3) were simultaneously estimated from the modulat ions.