Study On Gas Sensitive Properties Of Graphene-nano-coated Photonic Crystal Fiber

The sensor has a wide range of applications,which is an important pillar of modern information technology and high-tech development.Gas sensing technology has an important measured application in hydrogen sulfide,carbon monoxide,carbon dioxide,ammonia,sulfur dioxide,nitrogen oxide gases because these gases are toxic and harmful.With the modern society development,it is necessary to quickly and accurately detect harmful and flammable gases with excellent performances of the sensors.In recent years,the study of sensors of the photonic crystal fiber is very extensive.The photonic crystal fiber can also be called microstructure fiber and porous fiber,which has a wide range of applications in optical fiber communication,fiber optic devices,optical fiber sensing because of special structure and optical properties,especially in optical fiber sensing.Graphene has a hexagonal lattice structure,which is consists of six carbon atoms with the single layer thickness of 0.334 nm.In this work,the photonic crystal fiber and the emerging graphene nanomaterial are combined to prepare the graphene-coated photonic crystal fiber gas sensor.This work is new and not reported in the previous studies.The main research items are as follows:(1)The fusion welding of single-mode fiber and photonic crystal fiber was realized by using a Furukawa S178 A fiber splicing machine.The welding parameters and welding loss of photonic crystal fiber and ordinary single-mode fiber were investigated.The welding loss is as low as 0.03 dB and the microstructure of the tapered fiber is successfully prepared.(2)Based on the reduction of graphene oxide and the abovemethioned fiber,a graphene-coated photonic crystal fiber was fabricated as a sensor-sensitive element,and the thickness is 80 nm,including high temperature cacination reduction graphene oxide,optical fiber fixation,and graphene coating method.(3)A test chamber based on graphene-coated photonic crystal fiber-optic element was designed,and a gas-sensing test platform was successfully constructed with optical platform,computer,ASE broadband light source and AQ6370 D spectrum analyzer.(4)Different concentrations of hydrogen sulfide gas were prepared,which were introduced into the designed chamber,and the sensitivity test was carried out.The gas sensitivity of the graphene nano-coated photonic crystal fiber was analyzed according to the detected results were 31.43pm/ppm.(5)Cu nanoparticles were deposited on the basis of graphene-coated photonic crystal fiber by mixing calcination of graphene and Cu nanoparticles,and compared with the non-deposited graphene coating,and the spectral characteristics and gas-sensing properties were observed,the sensitivity were 42.03pm/ppm.(6)Combining the principle of optical fiber sensing and the structure of gas-sensing film,the spectral change process and the sensing mechanism are analyzed by analyzing the tested data and the relevant sensing theory.