Enhancing Gas Diffusion in Antiresonant Hollow-Core Fiber Gas Sensors Using Microchannels

In this paper, we analyze the performance of diffusion-based gas distribution in antiresonant hollow-core fiber-based gas absorption cells. Performed theoretical analysis was based on Fick's second law using the OpenFOAM (R) software and finite volume method (FVM), followed by an experimental verification of the obtained simulations. The diffusion time was tested for a 1.25 m long fiber, with laser-micromachined microchannels. Full analysis of the correlation between the microchannel count, position, and separation on the rate at which the fiber-based gas cell was filled with the target gas was presented. Experimental results showed that with the proper microchannel configuration, the purely-diffusion-based gas exchange time in the 1.25 m fiber could be reduced from 6 h, down to 330 s. Obtained results correlated with the simulations, giving perspective for the development and implementation of novel miniaturized passively filled gas absorption cells for compact laser spectrometers.