Interband GaSb-based laser diodes for spectral regions of 2.3-2.4 μm and 3-3.1 μm with improved room-temperature performance

The paper describes the heterostructures and device output parameters of Type-I quantum-well (QW) laser diodes with InGaAsSb active regions designed for room-temperature operation near 2.3 μm and 3.1 μm. For both designs decrease of the threshold current density and increase of the room-temperature output power have been achieved with increase of the QW depth for holes. For the 2.3 μm laser diodes, confinement of holes in the QW embedded into the AlGaAsSb waveguide was improved with increase of the hole energy level with compressive strain. Arrays of 1-mm-long 100-μm-wide laser diode emitters with a fill-factor of 30 % have been fabricated. A quasi-CW (30 μs, 300 Hz) output power of 16.7 W from a 4-mm-wide array has been obtained with conductive cooling. For the laser diodes designed for room-temperature operation above 3 μm, the hole confinement was improved by lowering the valence band energy in the waveguide. Two approached were implemented: one with increase of the Al composition, and another with utilization of quinternary InAlGaAsSb waveguide with increased As composition compared to the conventional AlGaAsSb waveguide. With the quinternary waveguide approach, a room-temperature CW output power in excess of 130 mW and a threshold current as low as 0.6 A have been obtained at λ = 3 μm from 2-mm-long 100-μm-wide emitters.