Data Storage Institute, (A*STAR) Agency for Science, Technology and Research, Singapore.
Nanotechnology. 2011 Jun 17;22(24):245204. doi: 10.1088/0957-4484/22/24/245204. Epub 2011 May 4.
Arrays of planar symmetric gold quadrumers consisting of a central nano-disc surrounded by three similar nano-discs belonging to the D(3h) point group were designed and fabricated. Since the geometrical configuration of quadrumers is the same as planar trigonal molecules, nano-discs can play the roles of artificial atoms to study the coupling trends among them. The plasmonic properties of the nano-disc structures are investigated by reflection spectrum measurement and finite-difference time-domain calculation with good agreement. Plasmon interaction among the nano-discs is also studied via a mass-spring coupled oscillator model. A pronounced Fano resonance (FR) is observed for the fabricated nano-discs with inter-disk gaps of around 18 nm during light irradiation at normal incidence. Although the obtained FR is independent of the excitation polarization, the near-field energy spatial distribution can be flexibly tuned by the polarization direction. This has potential applications in nano-lithography, optical switching and nonlinear spectroscopy.
设计并制作了由中心纳米盘和三个属于 D(3h)点群的类似纳米盘组成的平面对称金四角形阵列。由于四角形的几何形状与平面三角分子相同，纳米盘可以起到人工原子的作用，以研究它们之间的耦合趋势。通过反射光谱测量和有限差分时域计算进行了纳米盘结构的等离子体特性研究，结果吻合较好。通过质量-弹簧耦合振荡器模型研究了纳米盘之间的等离子体相互作用。在正常入射光照射下，当纳米盘之间的间隙约为 18nm 时，所制备的纳米盘会出现明显的 Fano 共振（FR）。尽管所得到的 FR 不依赖于激发极化，但近场能量空间分布可以通过偏振方向灵活地进行调节。这在纳米光刻、光学开关和非线性光谱学等方面有潜在的应用。
