Room-temperature continuous-wave operation of quantum-cascade lasers at λ∼4 μm -: art. no. 041111

High-power cw lambda similar to 4 mu m quantum-cascade lasers (QCLs) are demonstrated. The effect of different cavity length and laser die bonding is also investigated. For a high-reflectivity-coated 11-mu m-wide and 4-mm-long epilayer-down bonded QCL, cw output powers as high as 1.6 W at 80 K and 160 mW at 298 K are obtained, and the cw operation is achieved up to 313 K with 12 mW. The laser exhibits a threshold current density of 1.96 kA/cm(2), a slope efficiency of 737 mW/A, and a maximum wall-plug efficiency of 0.9% under cw mode at 298 K. In pulsed mode, a maximum average power of 552 mW at 298 K is achieved at 45% duty cycle and a characteristic temperature is 176 K from 80 to 393 K. (c) 2006 American Institute of Physics.