High sensitive methane sensor based on twin-core photonic crystal fiber with compound film-coated side-holes

A high-sensitive methane sensor based on a twin-core photonic crystal fiber (PCF) is proposed and analyzed. Two ultra-large side-holes of the PCF are polished and coated with methane-sensitive film to achieve fast response and high sensitivity. The finite element method is used to investigate the relationship between gas sensing performance and structural parameters. With the increase of the methane concentration from 0 to 3%, the gas sensitivity and low detection limit can reach to 4.60 nm/% and 435 ppm, respectively. The proposed sensor with high sensitivity and simple structure has great practical value and application prospects for environmental gas monitoring.