Abstract
Strain compensated In(0.67)Ga(0.33)As/AlAs(0.8)Sb(0.2)/InP quantum cascade lasers emitting at wavelengths near 3.1 mu m at room temperature have been demonstrated. The lasers operate in pulsed mode with threshold current density of 3.6 kA/cm(2) at 80 K and 19.2 kA/cm(2) at 295 K. The peak optical power for an as-cleaved 3 mm long and 10 mu m wide ridge device exceeds 1 W per facet at 80 K and is around 8 mW at 295 K. The observed laser performance suggests that room temperature operation for these lasers remains possible beyond the predicted threshold for Gamma-L intervalley scattering of electrons in the upper laser levels.