Nano-Photonic and Optoelectronic Research Laboratory (NORLab), Faculty of Electrical and Computer Engineering,Shahid Rajaee Teacher Training University, Tehran 16788-15811, Iran
The propagation loss of a fiber can be increased by coupling core mode and surface mode which will deteriorate the performance of photonic bandgap fiber (PBGF). In this paper, we presented an aircore PBGF for gas sensing applications. By designing Λ = 2.63 μm, d = 0.95 Λ, and Rcore= 1.13 Λ, where Λ is the distance between the adjacent air holes, the fiber was single-mode, no surface mode was supported with fiber, and more than 90% of the optical power was confined in the core. Furthermore, with optimizing the fiber structural parameters, at wavelength of l = 1.55 μm that is in acetylene gas absorption line, significant relative sensitivity of 92.5%, and acceptable confinement loss of 0.09 dB/m, were simultaneously achieved.