Laser-based gas sensing using mid-infrared semiconductor lasers combined with hollow-core fibers

In this paper we presents a gas sensing setup based on interband cascade laser (ICL) and quantum cascade laser (QCL) combined with a negative-curvature hollow core fiber (HCF). We demonstrate simultaneous detection of water vapor, methane, nitrous oxide and carbon monoxide using wavelength modulation spectroscopy technique. With a 1m-long HCF we were able to record WMS signals with high signal/noise ratio for ambient concentrations of nitrous oxide and methane. Presented setup marks the first instance of a HCF-based sensor combining two mid-infrared semiconductor lasers (ICL near 3.3 μm and QCL near 4.5 μm) into a hollow-core fiber, giving good perspective for the development of portable, compact mid-infrared systems that enable multi-species detection with high sensitivity and selectivity.