Tailorable Zero-Phase Delay of Subwavelength Particles toward Miniaturized Wave Manipulation Devices
Tailorable Zero-Phase Delay of Subwavelength Particles toward Miniaturized Wave Manipulation Devices
复制标题
针对小型波操纵装置的亚波长粒子的可定制零相位延迟
DOI：
10.1002/adma.201502298
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发表时间：
2015
影响因子：
29.4
通讯作者：
Soukoulis Costas M.
中科院分区：
文献类型：
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作者：
Zhao Qian;Xiao Zongqi;Zhang Fuli;Ma Junming;Qiao Ming;Meng Yonggang;Lan Chuwen;Li Bo;Zhou Ji;Zhang Peng;Shen Nian-Hai;Koschny Thomas;Soukoulis Costas M.
随着对器件小型化的要求和对片上光学元件的需求的增加，单颗粒或单层亚波长器件受到高度追捧，特别是那些可以避免诸如体结构介质中的衍射等复杂机制的器件。然而，大多数现有的基于粒子的光控制研究都集中在利用单粒子[28，29]或多粒子纳米天线。[30]在这些情况下，调制波长（λ）与颗粒尺寸（l）的比率约为4，即λ/l ≤ 4，因此阻碍了装置的小型化。实现更小组件的一种方法是通过增加波长与粒度的比值来削弱磁偶极子和电偶极子之间的相干效应（图1）。可以满足长波长近似，并且可以观察到诸如通过近零磁导率（MNZ）实现的各向同性近零折射率的新现象。这些近零折射率材料具有许多有趣的波操纵特征，并且已经使用不同的机制[31-35]进行了证明，例如基于金属结构的ε-近零材料，[32，33]光子晶体中的狄拉克锥[34]和双曲材料。[35]重要的是，用于实现这些现象的介质不一定是优选的，因为光子晶体具有与目标波长相同数量级的尺寸，并且双曲材料表现出各向异性的零折射率，在其中波以相位振动，就像在空气中一样。到目前为止，由MNZ产生的近零各向同性介质尚未实现。此外，圆柱源在样品中的等相位传播，特别是亚波长层状结构，还没有实验证明。此外，这些米氏共振，电介质粒子具有可调谐性下的外部刺激，可以导致有趣的可调波控制设备的可能性。[36]在这项工作中，各向同性零折射率介质的亚波长尺寸和没有相位延迟将研究其潜在的应用在小型化的波操纵components.Light散射的小（相对于入射光波长）球形粒子是经典电动力学的一个基本课题，是基于衍射问题的精确Mie解。[37]半径为r 0、折射率为n的单个孤立介质球的散射场可以分解成一个多极级数，其中散射电场的2 m极项与
With the increasing requirements of device miniaturization and the need for on-chip optical components, single-particle or single-layer subwavelength devices are highly sought after, especially those which can avoid complicated mechanisms such as diffraction in bulk structural media. However, most existing research on particle-based light control has focused on the utilization of single particle [28, 29] or multiparticle nanoantenna.[30] In these cases, the ratio of the modulated wavelength (λ) to the particles size (l) is about 4, ie, λ/l≈ 4, thus hindering device miniaturization. One method of realizing smaller components is to weaken the coherence effect between the magnetic and electric dipoles by increasing the ratio of wavelength to the particle size (Figure 1). The long-wavelength approximation can be satisfied and novel phenomenon such as an isotropic near-zero index, achieved through near-zero permeability (MNZ), can be observed. These near-zero index materials possess many interesting wave manipulation features and have been demonstrated using different mechanisms [31–35] such as epsilon-near-zero materials based on metallic structures,[32, 33] Dirac cones in photonic crystals,[34] and hyperbolic materials.[35] Importantly, the media employed to achieve these phenomena are not necessarily preferred, as photonic crystals have dimensions on the same order of the targeted wavelength and hyperbolic materials exhibit an anisotropic zero-index, inside which the wave vibrates with the phase, just like in the air. So far, near-zero isotropic media resulting from an MNZ has yet to be realized. In addition, equiphase propagation for a cylindrical source in a sample, especially for a subwavelengthlayered structure, has not been experimentally demonstrated. Furthermore, these Mie resonant, dielectric particles possess tunability under external stimuli that can lead to the possibility of interesting adjustable wave-control devices.[36] In this work, an isotropic zero-index medium with subwavelength dimensions and no phase delay will be studied for its potential applications in the miniaturization of wave-manipulating components.Light scattering by small (relative to the incident light wavelength) spherical particles is a fundamental topic in classical electrodynamics and is based upon the exact Mie solution of the diffraction problem.[37] The scattered field of a single isolated dielectric sphere with radius r0 and refractive index n can be decomposed into a multipole series with the 2 m-pole term of the scattered electric field proportional to