Femtosecond pulses from a mid-infrared quantum cascade laser

Abstract

We report on the formation of near-transform-limited sub-picosecond pulses from a mid-infrared quantum cascade laser with several Watts of peak power. Starting from a frequency-modulated phase-locked state, which most efficiently exploits the gain from the active region, ultrashort high peak power pulses are generated via external pulse compression. The temporal nature of these pulses is assessed by means of coherent beatnote interferometry, optical sampling and an interferometric autocorrelation technique.