A methane concentration sensor with heightened sensitivity and D-shaped cross-section U-shaped channel utilizing the principles of surface plasmon resonance

Based on the lack of sensors for high concentration methane in life, the present study introduces a new type of D-shaped photonic crystal fiber utilizing surface plasmon resonance effects, designed for the detection of high concentrations of methane. Differing from conventional D-type photonic crystal fiber, this model coats a gold film on an open-loop channel for excitation. Through the finite element method analysis, the simulation results demonstrate, this sensor exhibits an effective scope of 1.24–1.32 for the refractive index of analyte. The escalation of the analyte's refractive index leads to a gradual intensification of the loss peak within the spectrum. And then remains stable. The sensor demonstrates excellent performance at a refractive index of 1.32, delivering a maximum sensitivity of 22000 nm/RIU and a resolution of 4.55∙10−6 RIU. Achieving the methane concentration detection in the range of 27%–45% was made possible through the establishment of the relationship between refractive index and methane concentration. According to simulation results, within the concentration scope of 29%–39%, the maximum detection sensitivity for methane can reach 700 nm/%. The sensor has simple structure and excellent performance. We conducted an analysis of how structural parameters impact the resonance spectrum with the goal of optimization. The outstanding sensing performance makes it more competitive in the field of methane concentration detection, and it is not only used for methane detection.