Abstract: The authors theoretically investigated the fluorescence enhancement of single molecules near the resonant silver nano-antenna. The optimal fluorescence effect occurs at the large optimal coefficient, defined by the ratio between the normalized near field and decay rate. It shows that when the polarization of dipoles is parallel to the polarization of incident field and the dipoles are located within the specific nanoregion of 30-100 nm away from the metallic surface, a large fluorescence enhancement is achieved. For the different polarazition of dipoles, the enhancement effects of emission are also discussed at different location of dipoles and different incident wavelength. The results are helpful in the experiment design of single molecular fluorescence near the plasmonic nano-antenna.

Key words: surface plasmon, single molecular fluorescence, near field enhancement, modified decay rates

摘要： 从理论上研究了发生表面等离激元共振时, 银纳米天线对其周围近场区域单分子荧光性质的影响。最优的荧光增益效果在电场增益率和弛豫系数变化率的比值(即优化系数)较大时发生。通过对优化系数的计算, 发现当荧光分子的偶极矩与入射光偏振相同时, 并且在距离纳米天线30～100 nm的近场区域内, 荧光增益效果最佳。讨论了不同偏振方向荧光分子在天线周围不同距离、不同方向的平面以及入射波长变化时对于荧光性质的影响, 可以为金属纳米天线调控荧光行为的实验给予指导。

关键词: 表面等离激元共振, 单分子荧光, 近场增益, 弛豫系数变化