Research On Design And Sensing Properties Of The Photonic Crystal Fiber Based On Surface Plasmon Resonance

The SPR sensor based on photonic crystal fiber is a new type of sensor developed in recent years.It has excellent characteristics such as small size and low propagation loss,and it also breaks through the limitations of application of many SPR technologies in traditional optical fibers,and has received extensive attention.In this paper,three PCF-SPR sensors were designed and simulated using COMSOL software and finite element method.The parameters affecting their sensing performance,such as the dimensions of the metallic material,the air hole size of the core,and the channel size of the liquid to be measured,were separately studied.A novel sensing structure of PCF-SPR based on gold nanowires is proposed.The gold nanowires are set at the junction of the liquid to be measured and the quartz core.The sensor achieves two low refractive index ranges of 1.27-1.36 and 1.23-1.29.The analysis of the loss spectrum shows that a strong resonant coupling can occur between a single gold nanowire and the core guided mode.The amplitude sensitivity increases first and then decreases with increasing wavelength,the maximum amplitude sensitivity is as high as 600 RIU^-1.The sensor avoids the process of coating in the micropores,reduces the manufacturing difficulty,and has a good application prospect.A novel PCF-SPR sensor with two open-ring channels is designed and described.Two layers of air holes set inside of the fiber core.There are two open rings analyte channel on both left and right side of quartz core,two thin gold films are deposited on the wall of the open-rings.When the refractive index of the medium to be measured changes from 1.23 to1.29,the resonance wavelength is between 2550 nm and 2900 nm.The sensitivity of the sensor is as high as 13,000nm/RIU,and the sensing resolution is about 7.69×10^-66 RIU.The amplitude sensitivity is sensitive to the refractive index of the analyte to be measured.When the refractive index of the analyte varies from 1.25 to 1.28,the maximum amplitude sensitivity can vary between 132 RIU^-1and 210 RIU^-1.The entrance size of the open-rings can be specifically designed according to the molecular size of the analyte serving the function of filtering.A PCF-SPR sensor with an annular analyte channel was proposed,loss spectrum analysis method is used in this study.The spectral sensitivity is up to 4500nm/RIU and the refractive index resolution is about 2.5?10^-5RIU.Based on this study,graphene is added and placed on the outside of the gold nanolayer,the sensitivity is significantly improved,and the average spectral sensitivity was 7500 nm/RIU,indicating that adding appropriate thickness of graphene to the PCF-SPR sensor can improve the sensor performance.