Transient spectroscopy with a current-switched semiconductor diode laser

We describe transient spectroscopic measurements with a current-switched se miconductor diode laser. Following a fast pulse modulation in the injection current of the diode laser, the diode laser frequency is switched by a few hundred MHz and, then, is scanned over 10 GHz range in a short-time evolut ion (<0.5 mu s). Free-induction decay based on the frequency switching and transient absorption spectroscopy of rubidium D1 lines based on the fast fr equency-scan are experimentally demonstrated. These fast spectroscopic meas urements are accomplished in a single-shot pulse modulation and are, thus, applicable to short-lived samples such as in flowing or combustion systems.