Design of methane sensor based on slow light effect in hollow core photonic crystal fiber

A tunable methane gas sensor is proposed and optimized by introducing a gas-sensitive film into the cladding air holes of hollow core photonic crystal fiber (HC-PCF). The characteristics of dispersion curve and group index of band-gap photonic crystal fiber are analyzed by the Plane Wave Expansion Method (PWM) and Finite Element Method (FEM). The results show that the micro-fluid infiltration technology can effectively improve the slow light characteristics of photonic crystal fiber (PCF), and make the central wavelength of slow-light region at the target gas absorption to discriminate the gas species. The coating technique allows the spectrum of absorption enhancement factor linearly shift with the increase of methane concentration, and the sensitivity can reach up to 0.794 nm/%. The sensor is simple and reliable with good linearity, which provides a new way for mixed gas measurements. (C) 2020 Elsevier B.V. All rights reserved.