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设计了一种基于介质光栅金属薄膜复合结构的折射率传感器。利用He-Ne激光器输出的632.8nm横磁偏振光激发复合结构中的表面等离子体,得到了高灵敏度的折射率传感器。运用有限元方法,数值模拟了具有不同光栅厚度、周期以及折射率的分析物的反射光谱。对占空比为0.5、金属薄膜厚度为45nm的复合结构进行了参数优化,得到最优参数为:光栅厚度100nm、光栅周期500nm。在最优参数条件下,计算了金属薄膜与具有不同折射率的分析物之间的界面共振角的变化,得到了高达500(°)/RIU的角灵敏度。该折射率传感器操作简单、成本低、角灵敏度高,具有很好的应用前景。
A refractive index sensor based on dielectric grating metal thin film composite structure is designed. Using the 632.8nm transverse magnetic polarized light output from a He-Ne laser to excite the surface plasmon in the composite structure, a highly sensitive refractive index sensor was obtained. Using the finite element method, the reflectance spectra of analytes with different grating thicknesses, periods and refractive indices were numerically simulated. For the composite structure with a duty ratio of 0.5 and a metal film thickness of 45 nm, the optimal parameters were obtained: grating thickness 100 nm and grating period 500 nm. Under optimal parameters, the change of the interface resonance angle between the metal thin film and the analytes with different refractive indices was calculated and the angular sensitivity was obtained up to 500 (°) / RIU. The refractive index sensor has the advantages of simple operation, low cost, high angular sensitivity and good application prospect.