Next-Generation Mid-Infrared Chemical and Biological Sensors: Combining Quantum Cascade Lasers with Thin-Film and Hollow Waveguides

Mid-infrared (MIR, 3-20 mu m) sensor platforms are increasingly adopted in chemical and biological analysis, and they are applied in areas ranging from process monitoring to medical diagnostics. Because of the inherent access to molecule-specific fingerprints via well-pronounced fundamental vibrational, rotational, and rotovibrational transitions, quantitative information at parts-per-million to parts-per-billion concentration levels and beyond is achievable in solids, liquids, and gases. In particular, the combination of quantum cascade lasers (QCLs) with correspondingly tailored waveguide technologies serving as optical transducers thin-film waveguides for liquid-solid phase analysis, and substrate-integrated hollow waveguides for gaseous samples facilitates the use of miniaturizable and integrated optical chemical and biological sensors and diagnostics for applications such as exhaled breath analysis, food safety, and environmental monitoring.