Simultaneously at two wavelengths (5.0 and 7.5 mu m) singlemode and tunable quantum cascade distributed feedback lasers

Quantum cascade distributed feedback (QC-DFB) lasers based on a heterogeneous-cascade two-wavelength active waveguide core and a multisectioned cavity featuring two different Bragg gratings are demonstrated. Optimised lasers display singlemode emission at lambda similar to 5.0 and 7.5 mum simultaneously and a tunability on both modes equal to single-wavelength QC-DFB lasers.