Extraordinarily wide optical gain spectrum in 2.2–2.5 μm In(Al)GaAsSb/GaSb quantum-well ridge-waveguide lasers

A wide optical gain spectrum with full width at half maximum Δλ≈350 nm has been demonstrated in midinfrared (2.2–2.5 μm) room-temperature-operated InGa(As)Sb/GaSb quantum-well (QW) ridge-waveguide diode lasers. A QW width of 200 Å ensured a small energy separation between the first and second quantized states in the QW. Transitions from both quantized states contributed equally to the overall gain spectrum when the optical loss was optimized.