High-temperature continuous-wave operation of lambda similar to 8 mu m quantum cascade lasers

We report single-mode continuous-wave operation of a lambda similar to 8 mu m quantum cascade laser at 140 K. The threshold current density is 4.2 kA/ cm(2) at 300 K in pulsed mode and 2.5 kA/cm(2) at 140 K in continuous wave for 2 mm long index-guided laser cavities of 20 mu m width. Wide stripe (W similar to 100 mu m), index-guided lasers from the same wafer in pulsed ope ration demonstrate an average T-0 of 210 K with other wafers demonstrating a T-0 as high as 290 K for temperatures from 80 to 300 K. This improvement in high-temperature performance is a direct result of three factors: excell ent material quality, a low-loss waveguide design, and a low-leakage index- guided laser geometry. (C) 1999 American Institute of Physics. [S0003-6951( 99)05402-9].