Mode-phase-difference photothermal spectroscopy for gas detection with an anti-resonant hollow-core optical fiber.

Zhao, Pengcheng; Zhao, Yan; Bao, Haihong; Ho, Hoi Lut; Jin, Wei; Fan, Shangchun; Gao, Shoufei; Wang, Yingying et al. · Nat Commun · 2020

basic_science · Level V

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Abstract

Laser spectroscopy outperforms electrochemical and semiconductor gas sensors in selectivity and environmental survivability. However, the performance of the state-of-the-art laser sensors is still insufficient for many high precision applications. Here, we report mode-phase-difference photothermal spectroscopy with a dual-mode anti-resonant hollow-core optical fiber and demonstrate all-fiber gas (acetylene) detection down to ppt (parts-per-trillion) and <1% instability over a period of 3 hours. An anti-resonant hollow-core fiber could be designed to transmit light signals over a broad wavelength range from visible to infrared, covering molecular absorption lines of many important gases. This would enable multi-component gas detection with a single sensing element and pave the way for ultra-precision gas sensing for medical, environmental and industrial applications.