This technology is suitable for spectroscopic applications, multi-species trace-gas detection, and measurements of broadband absorbers.

The external-cavity quantum cascade laser (EC-QCL) system is based on an optical configuration of the Littrow type. It is a room-temperature, continuous-wave, widely tunable, mode-hop-free, mid-infrared, EC-QCL spectroscopic source. It has a single-mode tuning range of 155 cm^–1 (≈8% of the center wavelength) with a maximum power of 11.1 mW and 182 cm^–1 (≈15% of the center wavelength), and a maximum power of 50 mW as demonstrated for 5.3 micron and 8.4 micron EC-QCLs, respectively. This technology is particularly suitable for high-resolution spectroscopic applications, multi-species trace-gas detection, and spectroscopic measurements of broadband absorbers.