Widely tunable mode-hop free external cavity quantum cascade lasers for high resolution spectroscopy and chemical sensing

Recent progress in the development of room temperature, continuous wave, widely tunable, mode-hop-free mid-infrared external cavity quantum cascade laser (EC-QCL) spectroscopic sources is reported. A single mode tuning range of 155 cm(-1) (similar to 8% of the center wavelength) with a maximum power of 11.1 mW and 182 cm(-1) (similar to 15% of the center wavelength) with a maximum power of 50 mW was obtained for 5.3 and 8.4 mu m EC-QCLs respectively. This technology is particularly suitable for high resolution spectroscopic applications, multi species trace-gas detection and spectroscopic measurements of broadband absorbers. Several examples of spectroscopic measurements performed using EC-QCL based spectrometers are demonstrated.