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

We study photothermal phase modulation in gas-filled hollow-core optical fibers with differential structural dimensions and attempt to develop highly sensitive practical gas sensors with an in-line Fabry-Perot interferometer for detection of the phase modulation. Analytical formulations based on a h...

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Bibliographic Details
Published in:Optics express 2020-02, Vol.28 (4), p.5423-5435
Main Authors: Bao, Haihong, Hong, Yingzhen, Jin, Wei, Ho, Hoi Lut, Wang, Chao, Gao, Shoufei, Wang, Yingying, Wang, Pu
Format: Article
Language:English
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Summary:We study photothermal phase modulation in gas-filled hollow-core optical fibers with differential structural dimensions and attempt to develop highly sensitive practical gas sensors with an in-line Fabry-Perot interferometer for detection of the phase modulation. Analytical formulations based on a hollow-capillary model are developed to estimate the amplitude of photothermal phase modulation at low modulation frequencies as well as the -3 dB roll-off frequency, which provide a guide for the selection of hollow-core fibers and the pump modulation frequencies to maximize photothermal phase modulation. Numerical simulation with the capillary model and experiments with two types of hollow-core fibers support the analytical formulations. Further experiments with an Fabry-Perot interferometer made of 5.5-cm-long anti-resonant hollow-core fiber demonstrated ultra-sensitive gas detection with a noise-equivalent-absorption coefficient of 2.3×10 cm , unprecedented dynamic range of 4.3×10 and
ISSN:1094-4087
1094-4087
DOI:10.1364/OE.385670