Anti-Resonant Hollow-Core Fiber Sensor With Microchannel Arrays for Fast CO2 Sensing
A fast carbon dioxide (CO2) sensor utilizing an anti-resonant hollow-core fiber with microchannel arrays is demonstrated, where the microchannel arrays along the fiber cladding are precisely fabricated by a femtosecond laser to enhance the internal gas mass transfer rate to speed up the response. We utilized the method of direct absorption spectroscopy to calibrate the fiber sensor within a CO2 concentration range of 1% to 10% at the $2~\mu $ m wavelength band. A sensitivity of 0.155 a.u./% with a high linearity (R2) of 0.9935 in the experimental detection is characterized at 2004.33 nm. Meanwhile, the design of microchannel arrays along the fiber significantly improves diffusion dynamics, which reduces the response time from 355 s to 185 s at the steady state and achieves a limit of detection of 896.1 ppm. Benefiting from rapid dynamic response and excellent repeatability, the proposed fiber sensor provides a highly efficient in-line gas cell solution for the real-time quantitative monitoring of trace gases.