High-power, continuous-wave, current-tunable, single-mode quantum-cascade distributed-feedback lasers at λ ≅ 5.2 and λ ≅ 7.95 μm

Quantum-cascade distributed-feedback lasers with high-power, continuous-wave (cw), tunable, single-mode emission are reported. The emission wavelengths are near 5.2 and 7.95 μm. The lasers are operated at liquid-nitrogen temperature and above. A maximum output power of >100 mW is obtained per facet 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 with either heat-sink temperature or cw current is demonstrated. The tuning coefficients are 0.35 nm/K (5.2 μm) and 0.51 nm/K (7.95 μm) 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.