Research On Humidity Sensing Based On Fabrication Of M-Z Optical Fiber Microstructure Sensor And PCF Simulation

Microstructured optical fibers are widely used in environmental monitoring,food safety,chemistry,biomedicine and other fields;moisture-sensitive material graphene oxide(Graphene Oxide,GO)can increase the sensitivity of optical waveguide devices by adsorbing water molecules and changing its own refractive index.Based on surface plasmon resonance(Surface Plasmon Resonance,SPR),the metal layer can also be protected from oxidation.Compared with the existing optical fiber humidity sensor,this thesis conducts research on the preparation of humidity sensitive material GO,Mach-Zehnder(Mach-Zehnder,M-Z)sensing unit,theory and structural design based on finite element simulation,and proposes and A finite element-based GO composite microstructure fiber optic humidity sensor system is designed.First,the paper analyzes the principle of refractive index change caused by humidity-sensitive material GO and M-Z structure fiber under the influence of humidity.Through the COMSOL Multiphysics full vector finite element simulation software,the electric field of the optical fiber composite sensitive material sensing unit is simulated,and the material property changes of different sensing units are studied through theoretical derivation and simulation,which lays the foundation for the research of microstructure optical fiber humidity sensing basis.Secondly,GO is prepared by the improved Hummers method,the M-Z sensing structure fiber(multimode fiber-single-mode micro-nano fiber-multimode fiber)is obtained using the fiber fusion taper machine and fiber fusion splicing mechanism,and then the GO Coated on single-mode micro-nano fiber.Construct a fiber optic humidity sensing system with a direct high frequency optical path,and conduct humidity sensing experiments on different fiber optic MZ sensing structures within a humidity range of 49%RH?70%RH,and the sensitivity of the fiber optic MZ sensing structure is as high as 44.1pm/%RH Humidity sensor.Finally,using COMSOL,an Ag-GO coated PCF humidity sensor based on SPR effect was designed.By covering the outer side of the photonic crystal fiber(Pohotonic Crystal Fiber,PCF)cladding with a metallic argentum film and a graphene oxide film,a high-sensitivity photonic crystal fiber humidity sensor based on surface plasmon resonance was designed.The PCF surrounds two rows of regularly arranged small air holes of different sizes,and the outer two layers are respectively coated with argentum and graphene oxide(Ag-GO)to form the SPR sensing channel.At the same time,the outer layer is doped with agarose gel material to form the humidity sensing medium layer,and the outermost layer uses a perfect matching layer(PML)to limit light loss.Numerical analysis results show that the humidity sensitivity of the sensing structure is as high as 0.3183 d B/%RH.In addition,it can achieve an average sensitivity of 0.2131 d B/%RH in the range of 10?60%RH,which can be widely used in the field of intelligent detection and safety monitoring.