ROOM-TEMPERATURE CONTINUOUS-WAVE METAL GRATING DISTRIBUTED FEEDBACK QUANTUM CASCADE LASERS

We report on the design and elaboration of continuous wave (cw) distributed feedback quantum cascade lasers (QCLs) using a simple metal grating approach without epitaxial regrowth, neither for the grating nor for the thermal extraction. Room temperature cw single monomode QCLs with 30 dB side mode suppression ratio are demonstrated down to 4.5 ?m with 20 mW output power and threshold of 1.5 kA?cm-2. The beam quality factor (M2) does not exceed 1.22 for both axes. These results are discussed and the key issue of thermal management of the device is emphasized.