为了有效提升光纤表面等离子体共振(SPR)传感器场增强效果的响应速度和场增强特性, 采用悬挂芯光纤结合表面等离子体共振增强检测机理来提高表面场增强程度, 提出了一种新型的光纤SPR-表面场增强芯片结构。采用有限元理论分析了上述结构的光场特性, 由分析可知, 当薄膜层在40nm~50nm附近时存在比较强的场增强; 场增强程度与激发SPR共振波长密切相关; 而缩小包层厚度、降低纤芯折射率对比度也有利于大幅度增加场增强强度, 但半径和包层厚度变化对穿透深度几乎没有影响。结果表明, 优化后的光纤芯片具有较高的场增强效果。该研究为高灵敏、快速流体检测应用提供了一种解决思路。

For solving the problems of low surface intensity enhancement and slow response speed of fiber surface plasma resonance (SPR) sensors, a new type of optical fiber SPR-induced surface enhancement chip structure was proposed by using the mechanism of surface plasma resonance to improve the surface field enhancement degree. The characteristics of the proposed chip structure were analyzed based on the finite element method. When Au film layer thickness was near 40nm~50nm, a stronger field enhancement appeared. The degree of field enhancement was closely related with the transmitting wavelength. Reduction of cladding thickness, core diameter and refractive index contrast could increase the degree of field intensity enhancement, but radius and thickness of cladding had almost no effect on penetration depth. The results show that a good surface enhancement effort is feasible after optimization. The study could be beneficial for the application of fluid testing with high sensitivity and rapidity.