High-Peak-Power Room-Temperature $\lambda\sim 3.6\ \mu$m InGaAs–AlAs(Sb) Quantum Cascade Lasers

We report the development of high-peak-power λ ~ 3.6 μm 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 (~9% at 300 K) in the pulsed regime. The lasers are based on a vertical transition bound-to-continuum design. Devices of 30-μm 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.