泵浦光中有效频段对CARS信号选择激发作用的实验分析

Experimental Study on the Effective Frequency of the Pump Pulse to the Mode-Selective Excitation of the CARS Signals

运用基于遗传算法的自适应飞秒脉冲整形技术,实现了苯(C6H6,992 cm-1)和氘代苯(C6D6,945 cm-1)混合溶液中相干反斯托克斯(CARS)信号峰高分辨率的选择激发.谐波频率分辨光学开关(SHG-FROG)痕迹显示出飞秒CARS的选择激发主要是通过对泵浦光中与某待测振动模式相对应的有效频段的裁剪来实现的.通过在傅立叶平面对泵浦光进行频谱裁剪进一步在实验上验证了这一结论.该项研究成果对于进一步提高遗传算法搜索效率提供了重要思路.对于复杂分子系统飞秒CARS的选择激发研究具有深远意义.

High resolution mode-selective excitation of the CARS signal in the mixture of C6 H6 （992 cm^-1） and C6D6 （945 cm^-1） is experimentally achieved by adaptive femtosecond pulse shaping based on the genetic algorithm （GA）. The trace of second harmonic generation frequency-resolved optical gating （SHG-FROG） indicates that mode-selective excitation of the CARS mainly depends on the effective frequency components of the pump pulse related to specific molecular vibrational mode. This conclusion has been further experimentally demonstrated by masking the pump pulse at the Fourier plane. It provides important idea for improving the searching efficiency of GA and the experimental results have attractive potential applications in the complicated molecular system.