Tuning of mid-infrared diode lasers for spectroscopy operated in sub-/spl mu/s-pulses

Near room temperature operation and hence Peltier cooling for lead chalcogenide diode lasers can be achieved by using sub-/spl mu/s-pulses. At present, the typical CW low operation temperatures of these lasers limit their commercial gas analysis applications. We experimentally investigated the spectral characteristics concerning tuning width, temporal and current tuning rate, and mode behaviour of short pulsed diode lasers. For understanding of the pulse tuning, we present a qualitative thermodynamic model calculation. We observed for the first time a temporary negative tuning, that is opposite to the common mechanisms of temperature and current tuning.