Transient grating measurements at ultralow probe power

摘要

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 similar to 5 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 CrCl3, and a thin film of Cu vapor deposited on a Si substrate, demonstrating the flexibility of the technique. (C) 2020 Optical Society of America