Single-mode tunable quantum cascade lasers in the spectral range of the CO₂ laser at /spl lambda/=9.5-10.5 μm

Widely tunable, single-mode quantum cascade distributed feedback (QC-DFB) lasers based on a complex coupling scheme and operating in the wavelength range of the CO2laser (/spl lambda//spl ap/9.5-10.5 μm) are reported. Dynamic single-mode emission up to high current levels is obtained. The continuous single-mode tuning range is 150 nm, while the tuning range of the equivalent Fabry-Perot laser is /spl sim/400 nm. By homogeneously reducing all layer thicknesses by 10%, the wavelength coverage of a single QC-laser design can be extended to cover one entire regular band of the fundamental CO2laser spectrum.