Mode-phase-difference photothermal spectroscopy for gas detection with an anti-resonant hollow-core optical fiber
Pengcheng Zhao, Yan Zhao, Haihong Bao, Hoi Lut Ho, Wei Jin, Shangchun Fan, Shoufei Gao, Yingying Wang, Pu Wang
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.