Analysis of CH₄, C₂H₆, C₂H₄, C₂H₂, H₂, CO, and H₂S by forward Raman scattering with a hollow‐core anti‐resonant fiber

Abstract

Abstract Fiber‐enhanced Raman spectroscopy is applied actively for gas analysis. Hollow‐core anti‐resonant fibers (HC‐ARFs) with low loss and low spatial overlap between core and cladding modes show the potential of low background. We integrated an HC‐ARF into the Raman system, collected the forward scattering radiation with a lens‐coupled imaging spectrometer, and filtered most of the background through selection of region of interest. The limits of detection (LODs) of this system were determined as 1.2 ppm·bar for CH 4 , 2.9 ppm·bar for C 2 H 6 , 1.6 ppm·bar for C 2 H 4 , 2.7 ppm·bar for C 2 H 2 , 13.8 ppm·bar for H 2 , and 16.7 ppm·bar for CO with the excitation laser of 200 mW and the exposure time of 60 s. In addition, the LOD was better than 2.5 ppm·bar for H 2 S. By the detection of gas samples with the critical detectable concentration, it was proven that the estimated values of LOD from the preceding experimental results are reliable and the system had practical detectability. The gas samples we tested are relevant for multiple fields such as industrial process control and environment monitoring, showing the diversified application prospects of the Raman gas analysis system based on HC‐ARF.