Single-mode tunable quantum cascade lasers in the spectral range of the CO2 laser at lambda=9.5-10.5 mu m

Widely tunable, single-mode quantum cascade distributed feedback (QC-DFB) l asers based on a complex coupling scheme and operating in the wavelength ra nge of the CO2 laser (lambda approximate to 9.5-10.5 mu m) are reported. Dy namic single-mode emission up to high current levels is obtained. The conti nuous single-mode tuning range is 150 nm, while the tuning range of the equ ivalent Fabry-Perot laser is similar to 400 nm, By homogeneously reducing a ll layer thicknesses by 10%, the wavelength coverage of a single QC-laser d esign can be extended to cover one entire regular band of the fundamental C O2 laser spectrum.