摘要科研工作者们自Fano共振提出后就在该领域的不同系统中投入了很多精力。近年来，等离激元金属结构中的Fano共振成为了研究的热点。Fano共振之所以广受关注，是因为它在电磁诱导透明、高灵敏传感和慢光等领域具有广泛的应用。本文设计了两种等离激元结构，并对结构所具有的方向不敏感性Fano共振现象开展理论研究和模拟，具体工作如下：75591

1。 设计了一种由四个依次旋转900的子单元组成的金属棒组合结构。结构的子单元是由金构成的两个平行排列和一个垂直排列的金属棒构成。通过模拟结构的电磁响应，发现该结构显示出双Fano共振现象。双Fano共振现象分别来源于磁四极子和电偶极子的耦合以及电四极子和电偶极子的耦合。模拟还发现，该结构具有方向不敏感性，并且在两个Fano共振位置具有类电磁诱导透明特性。这种等离结构材料在光电子器件领域具有潜在的应用。

2。 设计了中心为一个圆柱/圆环型子单元、四周环绕六个圆柱/圆环型子单元的对称等离结构，模拟发现该结构展示出可调极化不敏感性Fano共振现象。通过将圆柱/圆环型簇结构中四周各圆柱沿径向向内、向外移动，结果发现，Fano共振的强弱、个数和位置与四周圆柱的位置密切相关，合适地选定圆柱的位置，可以获得不同特性的Fano共振，进而实现对Fano共振的调谐。此外，将模型加以旋转，发现Fano共振的强弱、个数和位置几乎没有变化，这表明该结构具有极化不敏感特性，这大大提升结构在光电器件方面的可能应用。

该论文有图22幅，参考文献68篇。

毕业论文关键词：等离激元结构  Fano共振  类电磁诱导透明  方向不敏感

Polarization-insensitive Fano resonances based on plasmonic structures

Abstract Since Fano resonances had been proposed, researchers have made great efforts on the realization of them utilizing different systems。 Fano resonances based on metamaterial and plasmonic structures have become a hot area in recent years。 Much attention to them lies in their many potential applications in electromagnetically induced transparency, high-sensitive sensing, and slow light。 In this paper, we proposed two plasmonic structures and carried out theoretical studies and simulations about the polarization-insensitive Fano resonances that the structures show。The main points of the letter are as follow:

1。A combined structure of which unit cell consists of four sub-units with 90-degree rotation in turn is designed。 Each of sub-units is composed of two gold rods in transverse arrangement and one gold rod in longitudinal arrangement。 Simulating electromagnetic responses of the structure, we verify that the structure exhibits double Fano resonances, which respectively origin from the coupling between magnetic quadrupoles and electric dipoles and the coupling between electric quadrupoles and electric dipoles。 Simulation results also demonstrate that the structure is polarization-insensitive and shows an analogue of electromagnetically induced transparency at the two Fano resonances。 Such a plasmonic structure has potential applications in photoelectric elements。

2。A symmetric plasmonic structure of which unit cell is composed of a cylinder/ring sub-unit-cell surrounded by six cylinder/ring sub-unit-cells is designed。 Simulating reflection and transmittance of the structure, we find that tunable porlarization-insensitive Fano resonances occur。 We also investigated the change rule of the Fano resonances when the six cylinders in the six cylinder/ring sub-unit-cells simultaneously move inward or outward。 It is found that the intensities, numbers and positions of the Fano resonances are relative close to the positions of the six cylinders。 Therefore, by shifting their positions, we can obtain different Fano resonances, which indicates that the Fano resonances are tunable。 Additionally, changing the polarization directions of the incident wave, we find that it is almost unchanged for the intensities, numbers and positions of the Fano resonances, implying that the structure is porlarization-insensitive。