等离子体纳米结构Fano谐振的Q值计算研究  

The Study of Quality Factor Calculation of Fano Resonance in Plasmonic Nanostructures

作　　者：胡治朋 刘芬[1] 刘柳[1] 张渊[1] 

机构地区：[1]华南师范大学华南先进光电子研究院,光及电磁波研究中心,广州510006

出　　处：《华南师范大学学报（自然科学版）》2016年第1期47-51,共5页Journal of South China Normal University(Natural Science Edition)

基　　金：国家自然科学基金项目(61108022);广东省自然科学基金项目(201001D0104799318)

摘　　要：品质因子(Q值)是谐振模式电磁存储能力的一个重要评价指标,文中从定义出发得到了Q值的时域拟合公式,并结合时域有限差分方法对典型金属纳米结构以及Fano谐振各特征模式的Q值展开研究;此外,用较为简单方便的频域半高宽公式对上述结构进行了Q值计算.通过对比2种方法得到的结果,发现尽管频域半高宽公式能够适用于简单的金属纳米结构谐振模式Q值计算,但在处理Fano谐振的Q值时将会带来较大的误差,有时甚至极大地偏离实际值导致计算结果失去意义.文中采用的时域拟合Q值公式从谐振模式的本质出发,不受结构响应谱线型的影响,适用于各种情况下对谐振模式Q值的准确计算.Fano resonance in plasmonic nanostructures has been attracted more and more attentions because of its special optical properties and application potential. Quality factor （ Q factor） is very important to evaluate the abili- ty of electromagnetic energy storage of a resonator. In this paper, the fitting formula in time domain is firstly got from the original definition of the Q factor; based on this formula and combining with FDTD method, the Q factors of typical resonance of several plasmonic nanostructures （ including metallic nanorod, nano-antenna and one sample showing evident Fano resonance） is calculated. Besides, the Q factor is also calculated by using the common fre- quency method （ the FWHM formula）. By comparing calculation results from the two method above, it is found that the FWHM formula is not suitable （sometimes incorrect） when dealing with the Q factor of Fano resonance, al- though it could be accuracy enough and fast when treating simple plasmonic resonance with single peak; while the Q factor fitting formula from FDTD method could be used for all type of plasmonic resonance （ including Fano reso- nance） because of its direct origin from the definition of Q factor.

关 键 词：Q值 金属纳米结构 表面等离子体光子学 Fano谐振 

分 类 号：O436.2[机械工程—光学工程]