研究了一种基于波分复用原理的准分布式光纤表面等离子体波传感器。应用光波导理论和多层膜反射理论分析了表面等离子体波效应在同一光纤探头中连续被激励的原理及其传感模型。通过数值模拟和相应实验分别考察了蒸镀调制层对表面等离子体波共振(SPR)效果的影响, 并在此基础上给出了设计的一般步骤和原则。实验结果表明, 蒸镀不同厚度的Ta2O5薄膜将导致表面等离子体波共振光谱发生偏移, 且随着膜厚增加而逐渐发生红移; 当液体折射率n0处于1.333～1.388之间时, 蒸镀有Ta2O5薄膜的光纤表面等离子体波传感器波长灵敏度达到2235 nm/RIU(Refractive Index Unit); 通过在一支光纤探头上依次加工两个表面等离子体波传感区域, 实现了对光波信号的连续调制。

A quasi-distributed optical fiber surface plasmon resonance (SPR) sensor based on wavelength division multiplexing is studied. Theory and sensing model of SPR effect excited continuously in the same optical fiber probe are analyzed with light waveguide theory and multi-layer reflection theory. Influences of thickness and type of modulation layer on resonance effect are analyzed quantitatively by utilizing numerical simulation and experiment, and the design approach and principle are also presented. The experiment shows that the variety of thickness of Ta2O5 film will lead to the change of SPR spectrum. Resonance dip shifts gradually to longer wavelength as the thickness of Ta2O5 film becomes thicker. For the range of liquid refractive index from 1.333 to 1.388, the measuring sensitivity of optical fiber SPR probe coated Ta2O5 film can up to 2235 nm/RIU (Refractive Index Unit). Broadband light can be modulated continuously by processing two SPR sensing areas within one optical fiber probe.