Research On Mach-Zehnder Gas Sensor Based On Photonic Crystal Fiber

With the development of society and the progress of science and technology,the process of industrialization and urbanization is accelerating.At the same time,there are a large number of toxic and harmful gases in industrial production,which are extremely harmful to human security.Therefore,it is extremely important to develop testing equipment for detecting flammable,explosive and toxic and harmful gases.Photonic Crystal Fiber(PCF)contains various arrangements in cross section.These air holes run all over the fiber.This unique structure produces some unique properties and is used for sensing.The potential of the sensing field combined with sensitive substances can gain new properties and provide new vitality for the development of optical fiber sensing technology.In this paper,solid photonic crystal fiber is used as the research object.Acarbon monoxide fiber gas sensor based on the Mach-Zehnder interference with copper oxide/polyanilino composite material coated on the surface of photonic crystal fiber,which combined with single-mode fiber.This article has done the following work:(1)The welding parameters were optimized through experimental investigation.The Mach-Zehnder interference structure is successfully fabricated by using single mode fiber and photonic crystal.(2)According to the principle of Mach-Zehnder interference,the working principle of the sensor is studied,and the length of PCF in the structure is confirmed by experiment.(3)Polyaniline is combined with copper oxide.The X-ray photoelectron spectroscopy(XPS)characterization showed that the copper oxide/polyaniline composite is successfully prepared.The composite is coated on the surface of PCF by dip coating method and the thickness is about 2 ?m.(4)The coated PCF is fused with the single-mode fiber to produce a carbon monoxide fiber gas sensor.A high sensitivity of 17 pm/ppm and a good linear relationship are achieved within a measurement range from 0 to 75 ppm.The response time and recovery time are about 80 s and 110 s respectively.(5)Corroding of the PCF cladding layer with 40% HF solution to increase the sensitivity of the structure to the external refractive index.