Methane sensing inside anti-resonant hollow-core fiber in the near- and mid-infrared spectral regions

Anti-resonant hollow-core silica fiber is used to demonstrate near- and mid-infrared laser absorption spectroscopy of methane. Molecular transitions near 6057 cm-1 (~1651 nm) and at 3057.7 cm-1 (~3270 nm) are targeted. Distributed feedback laser diode and interband cascade lasers are used as tunable laser sources. Detection of methane in ambient air is demonstrated using this mid-infrared system.