Fig. 5.
Lifetime data for CW operation of a 6.39-mm QCL with uncoated facets and thick electroplated Au on the epi-side contact, mounted epi-down on an AlN submount. Conditions were as follows: drive current, 1.25 A CW; Tsubmount = 25°C; active TEC temperature control; nitrogen-rich air; intentional power cycling. Power variations are due to optical mode switching; however, average power in either of the modes does not degrade with run time. At t≈320 h, the data collection system failure led to the loss of data for ≈60 h. The laser, however, continued to function throughout.