Open AccessEthane detection with mid-infrared hollow-core fiber photothermal spectroscopy
Author(s) -
Feifan Chen,
Shoulin Jiang,
Wei Jin,
Haihong Bao,
S. L. Ho,
Chao Wang,
Shoufei Gao
Publication year - 2020
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.410927
Subject(s) - materials science , optics , optical fiber , infrared , fiber , photothermal therapy , fiber optic sensor , optoelectronics , detection limit , core (optical fiber) , chemistry , nanotechnology , physics , composite material , chromatography
We report a compact mid-infrared (MIR) photothermal spectroscopic ethane (C 2 H 6 ) sensor with a hollow-core negative-curvature-fiber (HC-NCF) gas cell. The HC-NCF supports low-loss transmission of an MIR pump (3.348 µm) and a near-infrared (NIR) probe (1.55 µm). The pump and probe laser beams are launched into the gas cell from the opposite ends of the HC-NCF, allowing independent MIR pump delivery and NIR fiber-optic probe circuitry. The use of Fabry-Perot as the probe interferometer simplifies the sensor design and suppresses the common-mode noise in the lead in/out single-mode fiber. With a 14-cm-long HC-NCF, an ethane sensor system with the limit of detection (LOD) of 13 parts-per-billion (ppb) is achieved with 1 s lock-in time constant. The LOD goes down to 2.6 ppb with 410 s average time, which corresponds to noise equivalent absorption (NEA) of 2.0×10 -6 and is a record for the hollow-core fiber MIR gas sensors. The system instability is 2.2% over a period of 8 hours.