A reflective methane concentration sensor based on biconvex cone photonic crystal fiber

Abstract

A methane sensor based on photonic crystal fiber Mach-Zehnder interference is proposed. The sensor is a reflective sensor made by coating a section of photonic crystal fiber cladding with cryptophane molecule A/E sensitive film and fusing in the middle of single-mode fiber, forming two convex cones at the node and silver plating on the end face. The sensing principle is analyzed based on the mode interference theory of photonic crystal fiber, and the fabrication method of sensing film and sensing probe is introduced. The methane concentration response results when the sensing film is cryptophane molecule A or cryptophane molecule E is studied by experiments. The sensitivity of the sensor with cryptophane molecule A is 1.069 nm/% when the methane concentration is 0–5%. When the sensitive film is cryptophane molecule E, the sensitivity of the sensor is 1.272 nm/%. Due to its high sensitivity, simple structure and low cost, the sensor has a good prospect in various application fields.