| In recent years,photonic crystal optical fiber surface plasmon resonance（PCF-SPR）sensing technology has become one of the most influential research directions in the field of optical fiber sensing,due to its high sensitivity,strong real-time detection,label-free detection and other characteristics,it has great application value and potential in the fields of biosensing,food safety,environmental monitoring and other fields.In this paper,three D-shape PCF-SPR sensors with different structures are designed based on COMSOL software,and the influence of structural parameters on SPR resonant wavelength,spectral sensitivity and sensing performance is investigated,which provides a theoretical basis for the development of micro-nano fiber sensors with different performances.Design a D-shape polished PCF-SPR sensor.Through the simulation analysis of the metal species（indium tin oxide,gold and silver）coated on the polished surface,the influence of the parameter change of the thickness of the metal film on its sensing performance was studied.It was found that the sensor coated with indium tin oxide film had much better performance than the other two metal films,and its maximum wavelength sensitivity was 24800nm/RIU.In the refractive index detection range of 1.30-1.38,the average wavelength sensitivity is11205.24nm/RIU,and the average refractive index resolution is 8.92×10-6RIU.When the thickness of the metal film changes in the range of 75nm-90nm,the wavelength sensitivity of the sensor coated with indium tin oxide film changes the most obviously,and the wavelength sensitivity of the other two metal films changes very little.A D-shape indium tin oxide thin-film PCF-SPR sensor is proposed.The sensing characteristics are studied by finite element method,and the results show that the linear fit degree before optimizing the structural parameters is as high as 0.9873,the maximum wavelength sensitivity is 26000nm/RIU in the refractive index detection range of 1.30 to 1.39,the average wavelength sensitivity reaches 8981.9nm/RIU,the average refractive index resolution is 1.11×10-5RIU,and the maximum wavelength sensitivity after parameter optimization is 27500nm/RIU.The corresponding refractive index resolution is 3.64×10-6RIU.It can be seen that the wavelength sensitivity and refractive index resolution of the optimized PCF-SPR sensor are improved.A bisymmetric D-shape indium tin oxide thin-film PCF-SPR sensor was designed.The influence of structural parameters on sensor performance was studied by loss spectroscopy,and the relationship between structural parameters and wavelength sensitivity was obtained.The refractive index detection range of the sensor is 1.30-1.44,and the maximum wavelength sensitivity before optimizing the structural parameters is only 3300nm/RIU.After parameter optimization,the performance of the sensor has been significantly improved,the maximum wavelength sensitivity reaches 11200nm/RIU,and the refractive index resolution is 8.93×10-6RIU.PCF-SPR sensors have significant advantages in several aspects,such as spectral sensitivity and refractive index resolution.In the process of parameter optimization,it is found that when the diameter of the circular air hole,the distance between adjacent circular air holes,the width of indium tin oxide film,the long and short half axes of elliptical air holes and the thickness of indium tin oxide film change,the wavelength sensitivity of the sensor changes very small,indicating that the sensor has low requirements for accuracy in the production of these structural parameters,which can facilitate its large-scale production. |
