Distributed gas sensing with optical fibre photothermal interferometry

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.

Modeling and performance evaluation of in-line Fabry-Perot photothermal gas sensors with hollow-core optical fibers

“…Different types of HCFs such as HC-PCFs and anti-resonant hollow-core fibers (AR-HCFs) may be used for PT gas detection [2,[4][5][6][7][8][9]. Understanding PT phase modulation dynamics in these fibers with varying structural parameters is important for the design of sensors with optimal performance.…”

High-resolution distributed shape sensing using phase-sensitive optical time-domain reflectometry and multicore fibers

“…However, due to the recent development of specialty optical fibers like few-mode fibers [6], photonic crystal fibers [7,8] and hollow-core fibers [9], the breadth of potential applications for DOFSs has got enlarged. The synergy between specialty optical fibers and DOFSs makes it now possible to measure parameters that cannot be measured with the use of standard single-mode fibers, such as pressure sensing [10], axial stress sensing [11], or gas concentration [12]. On the other hand, multicore fibers (MCFs) were initially developed to face the capacity crunch of the optical fiber networks based on single-core fibers [13].…”

Combining Hollow Core Photonic Crystal Fibers with Multimode, Solid Core Fiber Couplers through Arc Fusion Splicing for the Miniaturization of Nonlinear Spectroscopy Sensing Devices

“…Owing to their unique structures and optical properties, HCFs successfully found application in many fields of science and techniques, including biological, chemical and environmental sensing. HCFs have been used in different kinds of sensing and measurement applications, i.e., temperature measurement [2][3][4][5], gas [6][7][8][9], strain [10], magnetic field [11], hydrostatic pressure [12], flying particle [13,14] and plasmonic sensors [15].…”