Watt level performance of quantum cascade lasers in room temperature continuous wave operation at λ∼3.76 μm

An InP-based quantum cascade laser heterostructure emitting at 3.76 μm is grown with gas-source molecular beam epitaxy. The laser core is composed of strain balanced In0.76Ga0.24As/In0.26Al0.74As. Pulsed testing at room temperature exhibits a low threshold current density (1.5 kA/cm2) and high wall plug efficiency (10%). Room temperature continuous wave operation gives 6% wall plug efficiency with a maximum output power of 1.1 W. Continuous wave operation persists up to 95 °C.