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High-power mid-infrared lasers based on type-II heterostructures with asymmetric band offset confinement

We have proposed a new physical approach to design mid-IR lasers based on type II heterostructures with strong asymmetric band offset confinement at the interface. It allows to create the high barriers for carriers and to reduce leakage current from an active region, that leads to increase the quantum efficiency of the emission due to the strong accumulation of recombining carriers. Here this approach was successfully used for fabrication high power lasers operating at (lambda) equals 3.26 micrometers . The laser structure containing narrow-gap active InGaAsEb (Eg equals 0.380 eV) layer and wide-gap confined InAsSbP (Eg equals 0.520 eV) and GaInAsSb (Eg equals 0.640 eV) layers lattice-matched to InAs substrate was grown by LPE. Such heterostructure has the band energy diagram with strong asymmetric band offsets and allows to provide high barriers for electrons at the InGaAsSb/GaInAsSb heterointerface ((Delta) Ec equals 0.60 eV) and for holes at the InGaAsSb/InAsSbP one ((Delta) Ev equals 0.15 eV). Maximum output power of 1.5 W was achieved in pulsed mode with pulse duration 1 microsecond(s) and repetition rate 100 Hz for 100 micrometers broad area laser with cavity length about of 1000 micrometers . Threshold current density was about 450 A/cm2. Characteristic temperature T0 equals 47 K was observed in the range of 77 - 140 K.