The influence of coherent transient energy transfer on femtosecond time-resolved Z-scan measurements

We investigate the influence of the coherent effect on femtosecond time-resolved Z-scan measurements using a degenerate pump-probe Z-scan technique. The time response of the light-induced transient grating (LITG) of Bi₂O₃-B₂O₃-SiO₂ (BI) glass shows a valley-peak variation, which has an obvious influence on the time-resolved Z-scan measurements. The valley-peak variation of the LITG signals with the delay time in BI glass is due to coherent transient energy transfer between positively chirped pump and probe pulses. The influence of the LITG effect on the closed-aperture time-resolved Z-scan measurements could be reduced by adjusting the position of the aperture transversely.