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使用飞秒时间分辨抽运-探测透射光谱技术,实验研究了GaAs体材料中光激发载流子的超快弛豫动力学的波长依赖.在相同的光激发载流子浓度和抽运/探测比时,发现760nm和780nm两中心波长处的瞬态透射变化延迟扫描信号出现负的和振荡的信号.与模拟计算结果对比,判定该实验瞬态信号是错误的.分析探测器输出波形,发现是由于反相波形导致的,而引起反相波形的原因在于样品中存在长寿命的吸收过程.指出通过提高探测器上的抽运/探测比能够矫正反相波形,从而获得正确的瞬态透射变化动力学.提高探测器上的抽运/探测比与目前的应尽量减小抽运光对探测器的散射贡献的观点是对立的.文章的研究结果对应用抽运-探测时间分辨光谱技术正确地测量超快瞬态动力学过程具有重要的参考价值.
Using the femtosecond time-resolved pump-probe transmission spectroscopy technique, the wavelength dependence of the ultra-fast relaxation kinetics of photoexcited carriers in GaAs bulk materials has been investigated experimentally. At the same photoexcited carrier concentration and pump / Compared with the experimental results, it is found that the negative and oscillatory signals of the transient transmission delay scan signals appear at the two center wavelengths of 760 nm and 780 nm, which are wrong compared with the simulation results.It is found that the output waveform of the detector is found Is due to the reverse phase waveform, which causes the reverse phase waveform because of the long-lived absorption process in the sample.It is pointed out that by increasing the pump-to-detect ratio on the detector, the reverse phase waveform can be rectified to obtain the correct transient transmission Variations of kinetics. Increasing the pump / detector ratio on the detector is antithetical to the current belief that the contribution of the pump light to the scatter of the detector should be minimized. The results of this study are based on the use of pump-detector time-resolved spectroscopy Correct measurement of ultra-fast transient dynamics has important reference value.