Abstract
We report the development of high-peak-power lambda similar to 3.6 mu m strain-compensated In(0.7)Ga(0.3)As-AlAs(Sb) quantum cascade lasers (QCLs). The QCLs operate up to at least 400 K with high wall-plug efficiency (similar to 9% at 300 K) in the pulsed regime. The lasers are based on a vertical transition bound-to-continuum design. Devices of 30-mu m width and 4-mm length, with high reflectivity coating on the rear facet, deliver more than 20-W peak optical power at 285 K with a threshold current density of 3.1 kA/cm(2). Over 2 W of peak power is obtained at 400 K.