High-power, continuous-wave, current-tunable, single-mode quantum-cascade distributed-feedback lasers at lambda congruent to 5.2 and lambda congruentto 7.95 mu m

Quantum-cascade distributed-feedback lasers with high-power, continuous-wav e (cw), tunable, single-mode emission are reported. The emission wavelength s are near 5.2 and 7.95 mu m. The lasers are operated at liquid-nitrogen te mperature and above. A maximum output power of >100 mW is obtained per face t at 80 K for both wavelengths, which is the result of careful positioning of the peak gain with respect to the Bragg wavelength. Continuous tuning wi th either heat-sink temperature or cw current is demonstrated. The tuning c oefficients are 0.35 nm/K (5.2 mu m) and 0.51 nm/K (7.95 mu m) for thermal tuning and vary from 20 to 40 nm/A for tuning with current. The lasers are being used in high-resolution and high-sensitivity gas-sensing applications . (C) 2000 Optical Society of America OCIS codes: 140.3070, 140.3600, 140.5 960.