Advanced gas sensors based on substrate-integrated hollow waveguides and dual-color ring quantum cascade lasers

This study shows the first combination of a ring-shaped vertically emitting quantum cascade laser (riQCL) providing two distinct emission wavelengths combined with a substrate-integrated hollow waveguide (iHWG). This ultra-compact riQCL-iHWG gas sensing device enables the simultaneous detection of two vapor phase species - here, furan and 2-methoxyethanol - providing distinctive absorption features at the emission wavelengths of the riQCL (i.e., 1144 and 1170 cm^-1). Hence, multianalyte gas sensing via a unique mid-infrared (MIR) sensor concept is demonstrated.