Diode lasers operating in spectral range from 1.9 to 3.5 μm

Mid-infrared lasers operating at room temperature (RT) in continuous wave (CW) mode are in demand for a variety of applications including laser detection and ranging, spectroscopy and infrared countermeasures. GaSb-based type-I quantum well (QW) diode laser technology addresses this demand providing compact lasers operating in spectral region from 1.9 to 3.4 μm, ex. [1,2,3]. The devices operate at voltages below 2 V and demonstrate RT CW power conversion efficiencies in excess of 25% near 2 μm and above 8 % at 3 μm [4]. These results show that Auger recombination does not preclude the CW RT operation of mid-infrared diode lasers. Low CW RT threshold current densities below 100 and 200 A/cm² obtained for 2 and 3 μm diode lasers, respectively revealed a bonus of the narrow bandgap QWs for laser development arising from the low density of states. This fundamental advantage became apparent in experiments after the optical and carrier confinement in active GaInAsSb QWs [5] were improved. This was achieved after the quaternary AlGaAsSb barrier material was replaced with the quinary AlGaInAsSb alloys [6]. In this work we report on progress in development of the metamorphic GaSb-based laser heterostructures and fabrication of the diffraction limited laser diodes.