Antiresonant hollow core fiber-assisted differential absorption spectroscopy of gas molecules

We present a proof-of-concept of the ARHCF-assisted gas molecules detection setup applying a non-wavelength modulation differential optical absorption spectroscopy (DOAS) technique to reduce an intermodal interferences effect and the compensation of changes in laser beam propagation parameters through ARHCF air-core. Toggled intensities of two air-core propagated laser beams have closely spaced wavelengths, while only one coinciding with targeted absorption line of acetylene at 1532.83 nm (~6524 cm-1). The difference in detected light intensities is used to determine a targeted gas concentration. Self-designed boxcar average unit allowed to 50 000 times/sec signals averaging, providing a minimal detection limit equal to 2.7 ppmv at 10s integration time.