Type-I quantum well cascade diode lasers emitting near 3 μm

Cascade GaSb-based type-I quantum well diode lasers were designed and fabricated. Cascade pumping was achieved utilizing efficient interband tunneling through "leaky" window in band alignment at GaSb/InAs heterointerface. The carrier recycling between stages was confirmed by twofold increase of the slope efficiency in two-stage devices as compared to reference single-stage lasers. Moderate internal optical loss increase was observed in cascade lasers with interband injector located near the optical mode peak. Cascade pumping scheme increased the continuous wave output power of room temperature operated 3 μm semiconductor lasers up to 590 mW and led to improved power conversion efficiency.