Liao Zhen, Pan Bai Cao, Shen Xiaopeng, Cui Tie Jun
Opt Express. 2014 Jun 30;22(13):15710-7. doi: 10.1364/OE.22.015710.
We present the occurrence of bright modes and dark modes in spoof localized surface plasmons (LSPs) generated by ultrathin corrugated metallic disks. As two such disks with asymmetric geometries are placed in close proximity, we find that dark modes (in multipoles) of one disk emerge by coupling with the bright modes (in dipoles) of the other disk. Then we further observe multiple Fano resonances due to destructive interferences of dark modes with the overlapping and broadened bright modes. These Fano line-shapes clearly exhibit the strong polarization dependence. We design and fabricate the ultrathin corrugated bi-disk structure in the microwave frequency, and the measurement results show reasonable agreement with theoretical predictions and numerical simulations. Such multiple Fano resonances could be exploited for the plasmonic devices at lower frequencies.
我们展示了由超薄波纹金属盘产生的类局域表面等离子体激元（LSPs）中亮模式和暗模式的出现情况。当两个具有不对称几何形状的此类盘紧密放置时，我们发现一个盘的暗模式（多极子）通过与另一个盘的亮模式（偶极子）耦合而出现。然后我们进一步观察到由于暗模式与重叠且展宽的亮模式的相消干涉而产生的多个法诺共振。这些法诺线形清楚地表现出强烈的偏振依赖性。我们在微波频率下设计并制造了超薄波纹双盘结构，测量结果与理论预测和数值模拟显示出合理的一致性。这种多个法诺共振可用于较低频率的等离子体器件。
