Hollow optical fiber based spectroscopy gas sensing

•Summarizes the manufacturing, connection, and post-processing technologies of HCF that are closely related to the performance of spectroscopic gas sensing systems.•Several HCF sensing structures (interferometers and gratings) which are widely used in gas sensing, are introduced.•The structure and performance of typical HCF-based DAS (direct absorption spectroscopy), PTS (photothermal spectroscopy) and PAS (photoacoustic spectroscopy) gas sensing system are analyzed. In recent years, the advantages of HCF as a gas analysis platform have been continuously explored. Gas sensing technology based on HCF spectroscopy has also developed rapidly, and the detection limit of such system has reached the level of several pptv. This article first summarizes the manufacturing, connection, and post-processing technologies of HCF that are closely related to the performance of spectroscopic gas sensing systems. Then, several HCF sensing structures (interferometers and gratings) which are widely used in gas sensing, are introduced. Next, the structure and performance of typical HCF-based DAS (direct absorption spectroscopy), PTS (photothermal spectroscopy) and PAS (photoacoustic spectroscopy) gas sensing system are analyzed. The development of HCF spectroscopic gas sensing technology is finally prospected.