1.9–3.3 μm Type-I quantum-well cascade diode lasers
GaSb-based type-I quantum well (QW) diode lasers can operate in continuous wave (CW) regime at room temperature (RT) in spectral range from 1.9 to 3.5 μm. CW output power levels from 100-μm-wide aperture of multimode lasers exceeded 1 W for devices emitting below 2.5 μm and hundreds of mW were achieved for lasers operating at longer wavelength. Recently cascade pumping of type-I quantum well gain sections was utilized to increase output power and efficiency of GaSb-based diode lasers. Carrier recycling between two QWs emitting near 3 μm led to reduction of the threshold current density from ∼200 down to ∼100 A/cm2 and increase of the maximum CW power level from ∼350 up to ∼650 mW compared to non-cascade diodes. Narrow ridge lasers fabricated from the same material demonstrated record 100 mW of CW power in nearly diffraction limited beam.