Theoretical And Methodological Research Of The Optical Fiber SPR Sensing Based On The Sensitivity Enhancement Of The Film Structure And Materials

Optical fiber Surface Plasmon Resonance（SPR）sensor is one of novel optical fiber sensors,which has the advantages of high sensitivity and label-free.It has shown broad application prospects in the fields of chemistry,biology,environment and medicine.In this dissertation,aiming at the urgent requirement of the sensitivity enhancement for the application in biology and health areas,the sensitivity enhancement mechanism and method research of optical fiber SPR sensing were carried out,from the optimization of the film structure and materials respectively.The whole theoretical model of the optical fiber SPR sensor for refractive index sensing was established,and two types of the optical fiber SPR sensor were fabricated,leading to refractive index sensing experiments with high sensitivity.Major innovations of this dissertation are including:1.The theoretical model of the dielectric waveguide-coupled SPR sensing with sandwich structure of three films was established,based on the transfer matrix calculation method of the multi-film structure.The influence of the film thickness,the metal materials type and the dielectric materials type on the performance of the sensor was investigated.When the sandwich structure of three films was Au 10 nm-Zn O 280nm-Au 20 nm,the sensor has the optimized performance.2.The complex permittivity of the Transition Metal Dichalcogenides（TMDCs）was calculated theoretically,based on the First Principle and the Density Functional Theory（DFT）.Based on the complex permittivity calculation,the theoretical model of the optical fiber waveguide-coupled SPR sensing with the TMDCs was established,and the influence of the film structure on the performance of the sensor was analyzed.The optical fiber waveguide-coupled SPR sensor with Zr S₂ as the dielectric film has the optimized performance,when the thickness of the gold film is 40 nm and the thickness of the Zr S₂ film is 240 nm.3.The dielectric waveguide-coupled SPR sensor with Au-Zn O-Au sandwich structure and the optical fiber waveguide-coupled SPR sensor with the TMDCs film were fabricated.The demodulation algorithm of the SPR wavelength was proposed based on all-phase filters,leading to the reduction of the demodulation error from 2 nm to 0.4 nm.With the two type senors,the refractive index sensing experiments was carried out,and the sensitivity can reach 4867 nm/RIU and 4544 nm/RIU respectively when the refractive index was 1.39 RIU.Combined with the Polydopamine（PDA）for sensitivity enhancement,the sensitivity can reach 9500 nm/RIU with the refractive index of 1.39 RIU.In addition,feasibility of the optical fiber waveguide-coupled SPR sensor for the biology immune-detection was tested by the specific experiments of the C-reactive protein（CRP）,which can monitor the whole process of the immunoreaction between antigen and antibody for CRP.