激励表面等离子共振的金属薄膜最佳厚度分析

根据电磁场在金属薄膜中的能量分布规律和金属薄膜具有复介电常数的特点，对激励表面等离子共振的金属薄膜的最佳厚度进行了探讨. 指出金属薄膜的最佳厚度与激励光波长和金属薄膜的折射率有关，建立了描述它们之间关系的数学表达式,并用实验方法进行验证. 将理论结果与他人的测量结果进行对比后发现，两者符合较好. 研究结果表明：在角度调制下的表面等离子共振传感器，为了获得更高的灵敏度，可根据激励光波长和金属薄膜折射率的虚部确定所要制备金属薄膜的最佳厚度；在波长调制下，则由中心波长和折射率的虚部确定金属薄膜的最适宜使用厚度. 关键词： 折射率 金属薄膜 全内反射 表面等离子共振

Research on the optimum thickness of metallic thin film utilized to excite surface plasmon resonance

The optimum thickness of metallic thin film utilized to support the surface plasmon resonance (SPR) has been investigated, based on the characteristics of electromagnetic field energy distributing in the film and its compound permittivity. It was shown that the optimum film thickness is related to the wavelength of exciting light and the refractive index (RI) of the metallic thin film. In this paper, a mathematical expression has been established to describe their relationship, and verified in the experiment. Our theoretical analysis is also consistent with previous experimental results. When the SPR sensor is employed in angular interrogation, in order to obtain highest sensitivity, the optimum thickness of metallic thin film can be deduced from the wavelength of the exciting light and the imaginary part of the film RI, or be obtained with the center wavelength of the exciting light and imaginary part of RI when the sensor is utilized in wavelength interrogation.