Continuous-wave distributed-feedback quantum-cascade lasers on a Peltier cooler

Continuous-wave operation of λ~9 <i>µ</i>m distributed-feedback quantum-cascade lasers is reported up to a temperature of 260 K. Single-frequency emission with a side mode suppression ratio of ≥27 dB and with a tuning range of 5 cm^–1 between 200 and 245 K (a tunability of –0.078 cm^–1/K and –0.764 cm^–1/W) is obtained for the junction-down mounted buried heterostructure devices. Uncoated lasers display an output power of up to 18 mW at 180 K and still 1 mW at 250 K. Lasers with high-reflection coated facets could be operated up to 260 K.