High-power, room-temperature, and continuous-wave operation of distributed-feedback quantum-cascade lasers at λ∼4.8 μm -: art. no. 041104

A high-power continuous-wave (CW) operation of distributed-feedback quantum-cascade lasers using a buried grating with epitaxial regrowth up to temperatures of above 60 degrees C is demonstrated. For a high-reflectivity-coated 13 mu m-wide and 3 mm-long cavity, CW output powers of 135 mW at 25 degrees C and still 37 mW at 60 degrees C are obtained. The device exhibits a CW threshold current density of 1.1 kA/cm(2), a maximum CW wall-plug efficiency of 1.48% at 25 degrees C, and a characteristic temperature of 177 K in pulsed mode. Single-mode emission near 4.8 mu m with a side-mode suppression ratio of > 30 dB and a tuning range of similar to 8.1 cm(-1) (i.e., tunability of 0.18 cm(-1)/K) in the temperature range from 15 to 60 degrees C is observed. (c) 2005 American Institute of Physics.