High-speed operation of gain-switched midinfrared quantum cascade lasers

We report on a simple technique for the generation of short pulses of midinfrared (5 and 8 μm) radiation, based on gain-switched quantum cascade lasers. In particular, an integrated step-recovery diode source (comb generator) is used to drive the lasers, properly packaged for high-speed operation. Using a fast HgCdTe detector, we measure optical pulses with duration as short as 200 ps, broadened by the detector response time, and peak power of a few tens of mW. The maximum operating temperature of these gain-switched sources is approximately 120 K.