Kim Kwang-Hyon, Kim Song-Hyok, Bae Myong-Chol
Appl Opt. 2015 Apr 1;54(10):2710-4. doi: 10.1364/AO.54.002710.
We demonstrate that pronounced Fano resonance can be obtained by dipole-hexapole coupling in a χ-shaped plasmonic nanostructure. The confined local field in the vicinity of dipole-resonant nanorods excites and coherently couples to the hexapolar mode in the rod perpendicular to the polarization direction of the incident wave, leading to strong Fano resonance. By using the discrete dipole approximation, we numerically investigate the behavior of Fano resonance by dipole-hexapole coupling in the plasmonic nanostructure. We obtain the parameters relevant to Fano resonance by fitting the coupled oscillator model equation to the calculated extinction data and investigate their dependencies on the structural parameters. The results demonstrate the possibility of obtaining high-contrast Fano resonance with narrow features by using this plasmonic nanostructure, which has potential applications for highly sensitive biological sensing, low-loss metamaterials, and others.
我们证明，在χ形等离子体纳米结构中，通过偶极-六极耦合可以获得显著的法诺共振。偶极共振纳米棒附近受限的局部场激发并相干耦合到垂直于入射波偏振方向的棒中的六极模式，从而导致强烈的法诺共振。通过使用离散偶极近似，我们数值研究了等离子体纳米结构中偶极-六极耦合的法诺共振行为。通过将耦合振子模型方程拟合到计算出的消光数据，我们获得了与法诺共振相关的参数，并研究了它们对结构参数的依赖性。结果表明，使用这种等离子体纳米结构有可能获得具有窄特征的高对比度法诺共振，这在高灵敏度生物传感、低损耗超材料等方面具有潜在应用。
