We report on an ultralow probe-power transient grating apparatus with probing based on a laser diode pulser, a digital delay generator, and a data acquisition card. The electronic triggering of the diode pulser permits stroboscopic measurement of arbitrarily slow laser-induced dynamics using pulses of probe light with average power $ {\sim} 5 \,\, {\rm nW} $, significantly lower than what is currently used by continuous wave measurement. The proposed method also allows for flexibility in selection of the probe wavelength limited only by availability of low threshold current laser diodes. Examples of impulsive stimulated thermal scattering measurements are presented on liquid isopropanol, single crystal solid $ {{\rm CrCl}_3} $, and a thin film of Cu vapor deposited on a Si substrate, demonstrating the flexibility of the technique.

中文翻译：

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超低探头功率下的瞬态光栅测量

我们报告了一种基于探针的超低探针功率瞬变光栅设备，该设备基于激光二极管脉冲器，数字延迟发生器和数据采集卡。二极管脉冲发生器的电子触发功能允许使用平均功率为{{\ sim} 5 \，\，{\ rm nW} $的探测光脉冲对频闪测量任意慢的激光诱导的动力学进行频闪测量，该功率明显低于当前使用的功率。连续波测量。所提出的方法还允许仅由低阈值电流激光二极管的可用性所限制的探针波长选择的灵活性。在液体异丙醇，单晶固体$ {{\ rm CrCl} _3} $以及在Si衬底上沉积的Cu蒸气薄膜，证明了该技术的灵活性。