Simultaneously at Two Wavelengths (5.0 and 7.5 mum) Single-Mode and Tunable Quantum Cascade Distributed Feedback Lasers

Quantum cascade distributed feedback (QC-DFB) lasers based on a hetergeneous-cascade active waveguide core and a multi-sectioned cavity featuring two different Bragg gratings are demonstrated. Optimized lasers display single-mode emission at lambda ~ 5.0 and 7.5 mum simultaneously and a tunability on both modes equal to single-wavelength QC-DFB lasers.