Photonic crystal fiber gas sensor for using in optical network protection systems

A new design of photonic crystal fiber based on octagonal array of air holes in the silica background is proposed for using as a sensor node in the optical network protection system of gas pipelines. The aim of our design is achieving more sensitivity and lowering the confinement loss. In addition, introducing a hollow high index ring with an air hole in the center of fiber simultaneously enhances the relative sensitivity and achieves low confinement loss. The dependence of sensing properties on the fiber parameters is numerically investigated by finite element method (FEM). We achieve the optimum design that has the relative sensitivity of 9.33% and the confinement loss of 6.8×10^-4 dB/m, at wavelength of λ=1.5μm. The results prove the ability of the proposed fiber in the optical wireless sensor networks as a gas or liquid sensor nod.