基于Kretschmann结构,建立了一种具有四层介质的光纤表面等离子体共振(SPR)传感器理论模型。通过仿真可知,当折射率为1.333~1.336时,反射波p、s偏振分量的相位差与折射率呈近似线性的变化关系,并得到了光纤SPR的传感测量公式。实验使用双频He-Ne激光器作为光源,提出了一套基于共光路结构的外差干涉光纤SPR测量系统,并采用相位解调的信号处理方法,使传感器具有较高的测量分辨率。甘油溶液的实验标定数据表明测量结果与理论分析一致,且结果与采用其他测量方法得到的结果吻合度较好,二者所得折射率的相互误差小于8.0×10 -5。所提传感器可以应用于环境检测、食品安全、药物筛选及临床医学等领域中。

This study builds an optical fiber surface plasmon resonance (SPR) sensor theoretical model with four-layered media based on the Kretschmann structure. Simulation results show that the phase difference between p- and s-polarized components changes almost linearly with the refractive index in the section of 1.333--1.336, deriving the sensor measurement formulas of optical fiber SPR. Using a dual-frequency He-Ne laser, an optical fiber SPR measurement system with heterodyne interferometry based on a common optical path structure is presented. A higher measurement resolution of the proposed sensor can be achieved through the signal processing method of phase demodulation. The experimental calibration data of glycerin solution show that the measurement results are consistent with the theoretical analysis. Results are in good agreement with those obtained by other methods, and the error of refractive index between the two methods is less than 8.0×10 -5. The proposed sensor can be applied in many fields such as environment detection, food safety, drug screening, and clinical medicine.