Part-per-billion level photothermal nitric oxide detection at 5.26 µm using antiresonant hollow-core fiber-based heterodyne interferometry

Abstract

In this work, I demonstrate a novel configuration of a photothermal gas sensor. Detection of nitric oxide at a wavelength of 5.26 µm was possible by constructing an absorption cell based on a self-fabricated antiresonant hollow core fiber characterized by low losses at both the pump and probe wavelengths. Proper design of the sensor allowed using the heterodyne interferometry-based signal readout of the refractive index modulation, which yielded a record noise equivalent absorption of 2.81×10 −8 cm -1 for 100 s integration time for mid-infrared fiber-based gas sensors. The obtained results clearly demonstrate the full potential of using properly designed antiresonant hollow core fibers in combination with sensitive gas detection methods.