High-Power Operation of Quantum Cascade Lasers Endured Prolonged Air-Oxidation

High-power strain-compensated In
_1-x
Ga
_x
As/In
_1-y
Al
_y
As quantum cascade lasers (lambda~5.5 mum) are demonstrated. Peak power at least 1.2 W per facet for a 32 mum times 2 mm uncoated laser stored in ambient condition for 240 days, is obtained at 80 K. Considering the collection efficiency of 60%, the actual output power is 4 W at this temperature.