Analysis of gas flow dynamics in hollow core photonic crystal fibre based gas cell

Gas flow dynamics in hollow core photonic crystal fibre (HC-PCF) is a trivial problem to study the gas filling time in HC-PCF gas sensor and other gas filled HC-PCF devices. This article analyzes the pressure dependence of gas diffusion coefficient in core and cladding holes of HC-PCF under the same condition of temperature and pressure during filling of methane and acetylene gas. An analytical model has been proposed to study the gas flow dynamics in core and cladding of HC-PCF. Due to gas filling, as the pressure varies inside the HC-PCF, at each increment of time, this model computes the change in pressure and respective gas diffusion coefficient. Using incremental gas diffusion coefficient, this model computes the gas filling time in a process similar to practical scenario. The gas filling time inside the core and cladding holes of HC-PCF for both methane and acetylene gas has been analyzed in this article. The results obtained can be utilized for HC-PCF based gas cell design.