Demonstration of a compact reflective gas sensing probe based on a negative-curvature hollow-core fiber

In this study, we demonstrate a compact reflective gas sensing probe based on a negative-curvature hollow-core fiber. The probe's design simplifies gas detection by eliminating the need for additional tubing, thereby improving the response time of gas sensing with hollow-core fibers. Using tunable diode laser absorption spectroscopy and wavelength modulation spectroscopy, we achieved detection limits of ∼1.5<i>p</i><i>p</i><i>m</i> for near-infrared methane sensing and below 100 ppb for mid-infrared detection. The probe's straightforward construction and compact form factor make it suitable for <i>in situ</i> measurements in hard-to-reach locations, offering a practical solution for gas leak detection and environmental monitoring.