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632.8 nm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45 nm的复合结构进行了参数优化,得到最优参数为:光栅厚度100 nm、光栅周期500 nm。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 with a composite structure based on dielectric grating with metal films is designed. The surface plasmas in the composite structure are excited by the transverse magnetic polarized light with a wavelength of 632.8 nm from a He-Ne laser and the refractive index sensor with a high sensitivity is obtained. With the finite element method, the reflection spectra for the analyte with different refractive indexes, grating thicknesses, and periods are numerically simulated. A grating thickness of 100 nm and a grating period of 500 nm are selected as the optimal parameters after the parameter optimization for the composite structure with a duty cycle of 0.5 and a metal film thickness of 45 nm. The variation of the resonance angle of the interface between the metal film and the analyte with different refractive indexes is calculated under the optimal parameters, and an angular sensitivity of 500 (°)/RIU is obtained. This refractive index sensor possesses the advantages of simple operation, low cost, and high angular sensitivity, which has considerable application prospects.