All-dielectric planar chiral metasurface with gradient geometric phase
All-dielectric planar chiral metasurface with gradient geometric phase
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DOI：
10.1364/oe.26.006067
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发表时间：
2018-03-05
期刊：
影响因子：
3.8
通讯作者：
Hong, Minghui
中科院分区：
文献类型：
--
作者：
Ma, Zhijie;Li, Yi;Hong, Minghui
超颖表面的平面光学手征测量其在左和右圆偏振（CP）光之间的差分响应，并且控制CP光的不对称传输。在2D超薄等离子体结构中，理论上圆二色性被限制在25%，并且它需要高吸收损耗。在这里，我们提出并数值演示了一个平面手性全介质超颖表面，表现出巨大的圆二向色性和传输不对称性超过0.8的圆偏振光可以忽略不计的损失，而不会带来双各向异性或违反互易性。超颖表面由高折射率锗Z形谐振器阵列组成，这些谐振器打破了面内镜面对称性并引起交叉偏振转换。此外，在一个手性的透射峰处，透射光被有效地转换成相反的圆偏振状态，其中指定的几何相位取决于光学元件的取向角。以这种方式，与用于基于几何相位的超表面的常规设置相比，不需要在超表面之前和之后设置光学组件以过滤某些圆偏振状态的光，并且超表面可以在任何线性偏振下起作用。作为概念的证明，数值模拟了基于几何相位手征超颖面的反常透射和二维全息。(C)根据OSA开放获取出版协议的条款，2018年美国光学学会
Planar optical chirality of a metasurface measures its differential response between left and right circularly polarized (CP) lights and governs the asymmetric transmission of CP lights. In 2D ultra-thin plasmonic structures the circular dichroism is limited to 25% in theory and it requires high absorption loss. Here we propose and numerically demonstrate a planar chiral all-dielectric metasurface that exhibits giant circular dichroism and transmission asymmetry over 0.8 for circularly polarized lights with negligible loss, without bringing in bianisotropy or violating reciprocity. The metasurface consists of arrays of high refractive index germanium Z-shape resonators that break the in-plane mirror symmetry and induce cross-polarization conversion. Furthermore, at the transmission peak of one handedness, the transmitted light is efficiently converted into the opposite circular polarization state, with a designated geometric phase depending on the orientation angle of the optical element. In this way, the optical component sets before and after the metasurface to filter the light of certain circular polarization states are not needed and the metasurface can function under any linear polarization, in contrast to the conventional setup for geometry phase based metasurfaces. Anomalous transmission and two-dimensional holography based on the geometric phase chiral metasurface are numerically demonstrate as proofs of concept. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement