Ashner Matthew N, Tisdale William A
Opt Express. 2018 Jul 9;26(14):18331-18340. doi: 10.1364/OE.26.018331.
Time-resolved femtosecond stimulated Raman spectroscopy (FSRS) is a powerful tool for investigating ultrafast structural and vibrational dynamics in light absorbing systems. However, the technique generally requires exposing a sample to high laser pulse fluences and long acquisition times to achieve adequate signal-to-noise ratios. Here, we describe a time-resolved FSRS instrument built around a Yb ultrafast amplifier operating at 200 kHz, and address some of the unique challenges that arise at high repetition-rates. The setup includes detection with a 9 kHz CMOS camera and an improved dual-chopping scheme to reject scattering artifacts that occur in the 3-pulse configuration. The instrument demonstrates good signal-to-noise performance while simultaneously achieving a 3-6 fold reduction in pulse energy and a 5-10 fold reduction in acquisition time relative to comparable 1 kHz instruments.
时间分辨飞秒受激拉曼光谱（FSRS）是研究光吸收系统中超快结构和振动动力学的有力工具。然而，该技术通常需要将样品暴露在高激光脉冲能量密度下并进行长时间采集，以获得足够的信噪比。在此，我们描述了一种基于工作频率为200 kHz的Yb超快放大器构建的时间分辨FSRS仪器，并解决了高重复频率下出现的一些独特挑战。该装置包括使用9 kHz的CMOS相机进行检测以及一种改进的双斩波方案，以抑制三脉冲配置中出现的散射伪像。与类似的1 kHz仪器相比，该仪器在实现良好信噪比性能的同时，还能将脉冲能量降低3至6倍，采集时间缩短5至10倍。
