High Q-factor with the excitation of anapole modes in dielectric split nanodisk arrays
High Q-factor with the excitation of anapole modes in dielectric split nanodisk arrays
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在电介质分裂纳米盘阵列中激发变极模式的高 Q 因子
DOI：
10.1364/oe.25.022375
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发表时间：
2017-09-18
期刊：
影响因子：
3.8
通讯作者：
Chen, Zhi-Hui
中科院分区：
文献类型：
--
作者：
Liu, Shao-Ding;Wang, Zhi-Xing;Chen, Zhi-Hui
同时实现高Q因子共振和强近场增强周围和内部的介电纳米结构是重要的许多应用在纳米光子学。然而，入射场通常被限制在介电纳米颗粒内，这导致与外部环境的光学相互作用差。通过适当的设计，近场增强可以扩展到电介质纳米结构的外部，但是由于额外的辐射损耗，Q因子通常会降低。本文表明，实现高Q因子的障碍，即，辐射损耗可以有效地抑制通过使用介质纳米盘阵列，其中的Q因子是约一个数量级大于与非辐射anapole模式和阵列的集体振荡的单盘。当电偶极模和次辐射模的共振能量彼此简并时，相消干涉产生类似于电磁感应透明的效应。此外，Q因子可以用介电分裂纳米盘阵列极大地放大，其中分裂间隙的存在不会引起额外的损耗。相反，通过调整差距宽度来修改两个干涉模式之间的耦合，这使得可以同时实现分裂盘周围和内部的高Q因子和强近场增强。结果表明，当差距为110 nm时，Q值接近106，且分裂圆盘的近场增强比单圆盘强两个数量级. (C)2017美国光学学会
The simultaneous realization of high Q-factor resonances and strong near-field enhancements around and inside of dielectric nanostructures is important for many applications in nanophotonics. However, the incident fields are often confined within dielectric nanoparticles, which results in poor optical interactions with external environment. Near-field enhancements can be extended outside of dielectric nanostructures with proper design, but the Q-factor is often reduced caused by additional radiation losses. This paper shows that the obstacles to achieve high Q-factor, that is, the radiative losses can be effectively suppressed by using dielectric nanodisk arrays, where the Q-factor is about one order larger than that of the single disks associated with the nonradiating anapole modes and the collective oscillations of the arrays. When the resonance energies of the electric dipole mode and the subradiant mode are degenerate with each other, the destructive interference produces an effect analogous to electromagnetically induced transparency. Furthermore, the Q-factor can be extremely enlarged with dielectric split nanodisk arrays, where the present of the split gap does not induce additional losses. Instead, the coupling between the two interfering modes is modified by adjusting the gap width, which makes it possible to achieve high Q-factor and strong near-field enhancements around and inside of the split disks simultaneously. It is shown that the Q-factor is approaching to 106 when the gap width is about 110 nm, and the near-field enhancements around and inside of the split disks are about two orders stronger than that of the single disk. (C) 2017 Optical Society of America