Mid-infrared quantum cascade laser based trace gas sensor technologies: Recent advances and applications

Recent advances in the development of trace gas sensors based on the use of quantum cascade lasers (QCLs) for the sensitive, selective detection, quantification and monitoring of small molecular gas species with resolved spectroscopic features will be described. High detection sensitivity at ppbv and sub-ppbv concentration levels requires detection sensitivity, enhancement schemes such as multipass absorption cells, cavity enhanced absorption techniques, or quartz enhanced photo-acoustic absorption spectroscopy (QEPAS).