基于双电介质层的棱镜表面等离子共振传感的研究

Study of Prism Surface Plasmons Resonance Sensor Based on Double Dielectric Layers

为了提高表面等离子共振系统的分辨率,提出了一种五层结构的表面等离子共振效应的激励模型:棱镜基底-银膜-电介质层1-电介质层2-待测介质.采用薄膜光学和波导理论,讨论了银和双电介质层复合而成的共振薄膜对表面等离子共振效应的激励机理与调制特性的作用.借助有限元分析方法,数值模拟得到双电介质表面等离子共振激励模型的共振光谱.分析结果表明,当待测介质折射率相同时,双电介质表面等离子共振激励模型共振光谱的半峰宽约为传统棱镜表面等离子体共振的0.1倍,理论计算得到双电介质表面等离子共振激励模型的系统分辨率相较于传统棱镜表面提高了5.4倍.以乙二醇溶液为待测样本,分析得到传感器的灵敏度约为7.2°/RIU,品质因数约为465,证明了该结构设计的可行性,为设计高分辨率和高品质因数的传感系统提供了理论参考.

To improve the system resolution of the surface plasmons resonance,a surface plasmons resonance incentive model based on the five-layer structure was proposed which is prism base-silverdielectric layer1-dielectric layer2-environment media.Silver film and double dielectric layers composed the composite resonance film.According to the thin film optics and waveguide theory,the effect of the double dielectric layer on the incentive mechanism and modulation characteristics of the surface plasmons resonance was discussed.Numerical simulation was conducted on the resonance spectroscopy of the double dielectric layers structure by finite element analysis method.The simulation result shows that,the full width half maximum of the double dielectric structure is about 0.1times narrower than traditional prism surface plasmons resonance when the refractive index of analyte is same.The resolution of the double dielectric layers structure is 5.4times higher than the traditional prism surface plasmons resonance.The ethylene glycol was adopted as the sample detected,the quality factor and sensitivity of the refractive index sensor were analyzed.The quality factor can attain 465 and the sensitivity can attain7.2°/RIU,which demonstrates the feasibility of the sensing structure.This structure provides a theoretical reference for the design of high resolution and high quality factor sensing system.