Design and optimization of index guiding photonic crystal fiber-based gas sensor

Hydrogen sulfide(H2S) and methane(CH4) are flammable, toxic, and colorless gases that exist in oil rigs/refineries. The PCF based gas sensors can detect the concentration of chemical materials such as hydrogen sulfide and methane. This paper presents a hexagonal PCF for sensing these gases. Characteristics of the proposed structure have been investigated for the wavelength range of 1.1 mu m-1.6 mu m using the full vector finite element method (FEM). The numerical results show that using non-circular holes around the central ring holes and a higher number of ring holes improves sensitivity and confinement loss respectively. Eventually, the relative sensitivity is enhanced to 62.07% and 67.07% and also the confinement loss 2.33 x 10(-9)dB/m and 8.61 x 10(-5)dB/m at the wavelength of 1.33 mu m and lambda = 1.578 mu m at which the CH4 and H2S have a strong absorption line, respectively.