银纳米棒四聚体的法诺共振和线宽压缩

Fano resonances in silver nanorod quadrumer and linewidth compression

利用有限元方法(FEM)研究了光场作用下由银纳米棒组成的四聚体(silver nanorod quadrumer,SNQM)的法诺共振(Fano resonances,FRs)和谱线线宽压缩现象。SNQM由两个相同纳米棒以上下平行排列方式组成的谐振腔(resonant cavity,RC)和由插入其中的两个相同纳米棒同向排列组成的偶极辐射天线(dipole antenna,DA)所构成,通过RC和DA的等离激元之间相互作用所形成的超辐射和亚辐射模式间相消干涉产生FRs现象。研究结果表明:调整SNQM的结构参数可对FRs的调制深度和共振波长进行调谐,在选取适当的结构参数的情况下可实现增强的窄线宽DA辐射。

With the finite element method （FEM）, the Fano resonances（FRs）and linewidth compression in a silver nanorod quadrumer （SNQM） system formed from four silver nanorods is investigated. The SNQM is made up of two dimers, one composed by two identical and parallel silver nanorods that can be regarded as a resonant cavity （RC）, the other is inserted in the DR composed by two same silver nanorods oriented in the same direction which can be taken as a dipole antenna （DA）. The results show that the distinct FRs are observed in the transmission spectra of the SNQM,which derives from the interference between the super radiant mode and the sub-radiant mode that caused by the interaction of the surface plasmons of the RC and DA. FRs can be tuned in both resonance wavelength and modulation depth by adjusting the structure parameters. Meanwhile, under the appropriate structure parameters, the narrow linewidth radiation of the DA can be enhanced in the RC.