Lin Linhan, Yi Yasha
Opt Express. 2015 Jan 12;23(1):130-42. doi: 10.1364/OE.23.000130.
Height induced coupling behavior between the plasmonic modes and diffraction orders were studied in the core-shell SiO(2)/Au nanocylinder arrays (NCAs) using finite difference time domain (FDTD) simulations. New lattice plasmon modes (LPMs) are observed in the structures with high aspect ratio. Specifically, parallel coupling between the plasmonic modes and diffraction orders is obtained here, which shows different coupling behavior from orthogonal LPMs. Electromagnetic (EM) field distributions indicate that horizontal propagation of the magnetic or electric field component is responsible for the generation of these orthogonal and parallel LPMs, respectively. Radiative loss could be effectively suppressed when the height increases. This is important for the applications of fluorescence enhancement and nano laser. Further studies confirm that the LPMs associated with the superstrate diffraction orders could be well maintained even when the Au coating is imperfect. The interference from the substrate associated LPMs could be eliminated by cutting off the corresponding diffraction waves by inducing a Si(3)N(4) substrate. This study of coupling behavior in the core-shell NCAs enables a novel route to design and optimize the LPMs for applications of bio-sensing and nano laser.
利用时域有限差分（FDTD）模拟研究了核壳结构的SiO(2)/Au纳米圆柱阵列（NCAs）中高度诱导的等离子体模式与衍射级次之间的耦合行为。在高纵横比的结构中观察到了新的晶格等离子体模式（LPMs）。具体而言，在此获得了等离子体模式与衍射级次之间的平行耦合，这显示出与正交LPMs不同的耦合行为。电磁场分布表明，磁场或电场分量的水平传播分别是产生这些正交和平行LPMs的原因。当高度增加时，辐射损耗可以得到有效抑制。这对于荧光增强和纳米激光器的应用很重要。进一步的研究证实，即使金涂层不完美，与上层衍射级次相关的LPMs也能得到很好的维持。通过引入Si(3)N(4)衬底切断相应的衍射波，可以消除与衬底相关的LPMs的干扰。对核壳NCAs中耦合行为的这项研究为设计和优化用于生物传感和纳米激光器应用的LPMs开辟了一条新途径。
