Distributed gas sensing with optical fibre photothermal interferometry

  • L. I.N. Yuechuan
  • , L. I.U. Fei
  • , H. E. Xiangge
  • , JIN Wei
  • , Min Zhang
  • , Fan Yang
  • , Hoi Lut Ho
  • , T. A.N. Yanzhen
  • , Lijuan Gu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

We report the first distributed optical fibre trace-gas detection system based on photothermal interferometry (PTI) in a hollow-core photonic bandgap fibre (HC-PBF). Absorption of a modulated pump propagating in the gas-filled HC-PBF generates distributed phase modulation along the fibre, which is detected by a dual-pulse heterodyne phase-sensitive optical time-domain reflectometry (OTDR) system. Quasi-distributed sensing experiment with two 28-meter-long HC-PBF sensing sections connected by single-mode transmission fibres demonstrated a limit of detection (LOD) of ~10 ppb acetylene with a pump power level of 55 mW and an effective noise bandwidth (ENBW) of 0.01 Hz, corresponding to a normalized detection limit of 5.5ppb.W/√Hz. Distributed sensing experiment over a 200-meter-long sensing cable made of serially connected HC-PBFs demonstrated a LOD of ~ 5 ppm with 62.5 mW peak pump power and 11.8 Hz ENBW, or a normalized detection limit of 312ppb.W/√Hz. The spatial resolution of the current distributed detection system is limited to ~ 30 m, but it is possible to reduce down to 1 meter or smaller by optimizing the phase detection system.

Original languageEnglish
Pages (from-to)31568-31585
Number of pages18
JournalOptics Express
Volume25
Issue number25
DOIs
Publication statusPublished - 11 Dec 2017

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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