Angle-selective all-dielectric Huygens' metasurfaces
Angle-selective all-dielectric Huygens' metasurfaces
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DOI：
10.1088/1361-6463/aa875c
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发表时间：
2017-11-01
影响因子：
3.4
通讯作者：
Staude, I.
中科院分区：
文献类型：
--
作者：
Arslan, D.;Chong, K. E.;Staude, I.
我们从实验和数值上研究了在近红外光谱范围内支持电偶极和磁偶极Mie型共振的由硅纳米盘组成的介电准表面的角度分辨传输特性。首先，我们集中于惠更斯亚表面，其特征是在垂直入射时硅纳米盘的基本电偶极子共振和磁偶极子共振的光谱重叠。由于阻抗匹配，惠更斯亚表面在共振的光谱宽度上表现出高的传输强度，而当波长扫过共振的宽度时，传输相位显示出2pi的变化。我们观察到惠更斯准表面的透射率依赖于入射角，并且对非垂直入射的偏振很敏感。当入射角从垂直入射开始增大时，两个偶极子共振移出光谱重叠，共振特征表现为显著的透过率极小值。接下来，我们考虑与惠更斯的亚表面相比，亚表面的纳米盘半径增加，惠更斯亚表面支持垂直入射时光谱分离的电偶极和磁偶极共振。我们表明，对于TM偏振，我们可以将这种亚表面的共振转换为光谱重叠，并在特定入射角度下恢复惠更斯亚表面的高共振透过率特性。此外，这两个超表面在它们各自的工作频率上被证明能够抑制所有入射角度不同于设计重叠角的TM偏振光。我们的实验观测与数值计算在定性上是一致的。
We experimentally and numerically study the angularly resolved transmission properties of dielectric metasurfaces consisting of silicon nanodisks which support electric and magnetic dipolar Mie-type resonances in the near-infrared spectral range. First, we concentrate on Huygens' metasurfaces which are characterised by a spectral overlap of the fundamental electric and magnetic dipole resonances of the silicon nanodisks at normal incidence. Huygens' metasurfaces exhibit a high transmitted intensity over the spectral width of the resonances due to impedance matching, while the transmitted phase shows a variation of 2 pi as the wavelength is swept across the width of the resonances. We observe that the transmittance of the Huygens' metasurfaces depends on the incidence angle and is sensitive to polarisation for non-normal incidence. As the incidence angle is increased starting from normal incidence, the two dipole resonances are shifted out of the spectral overlap and the resonant features appear as pronounced transmittance minima. Next, we consider a metasurface with an increased nanodisk radius as compared to the Huygens' metasurface, which supports spectrally separate electric and magnetic dipole resonances at normal incidence. We show that for TM polarisation, we can shift the resonances of this metasurface into spectral overlap and regain the high resonant transmittance characteristic of Huygens' metasurfaces at a particular incidence angle. Furthermore, both metasurfaces are demonstrated to reject all TM polarised light incident under angles other than the design overlap angle at their respective operation frequency. Our experimental observations are in good qualitative agreement with numerical calculations.