论文标题

基于耦合调整的相同纳米柱的不规则连续结构的“元原子”架构可实现高效且具有恰当的元时间

'Meta-atomless' architecture based on an irregular continuous fabric of coupling-tuned identical nanopillars enables highly efficient and achromatic metasurfaces

论文作者

Yağcı, Hüseyin Bilge, Demir, Hilmi Volkan

论文摘要

metasurfaces是次波长 - 厚的构建体,由离散的元原子组成,提供了离散的相位积累水平,共同近似设计的光学功能。利用几何相和偏振结构的几何阶段的元原子产生了包括金属在内的光学组件的实现。但是,迄今为止,这种方法的待处理和基本问题一直是这种产生的组件遭受的低设备效率,这是用于防止其元原子偶联的大晶格常数的不良副作用。尽管使用近场耦合来调整电磁共振发现其用于构建有效的窄带设计,但这种结构在广泛的范围内没有提供高效率。在这里,我们提出并表明,与连续调整的偶联距离的相同电介质纳米波导的紧密挤压织物可产生出色和完整的乳腺元素元素元素。该体系结构使散点器能够非常有效地与传入波相互作用。作为概念验证的示范,我们显示了一种具有分类的圆柱金属,该金属由单个几何形状的强耦合介电纳米圆柱形成,作为“ meta-at-ateless”的连续相位元素,以400-700 NM频段的整个方式工作。在整个光谱范围内,这将达到超过85%的焦点效率。为了打击极化敏感性,我们使用了六角堆积的纳米柱来构建与极化无关的散点子库。最后,获得了具有极化无关的操作和成分焦点的圆形金属。这是通过编织相同的纳米圆柱耦合到通过仔细调节构建的不规则晶格中的相同的纳米圆柱来制造出色的跨表面体系结构的范式转移。

Metasurfaces are subwavelength-thick constructs, consisting of discrete meta-atoms, providing discretized levels of phase accumulation that collectively approximate a designed optical functionality. The meta-atoms utilizing geometric phase with polarization-converting structures produced encouraging implementations of optical components including metalenses. However, to date, a pending and fundamental problem of this approach has been the low device efficiency that such resulting components suffer, an unwanted side effect of large lattice constants used for preventing inter-coupling of their meta-atoms. Although the use of near-field coupling for tuning electromagnetic resonances found its use in constructing efficient narrow-band designs, such structures fell short of providing high efficiency over a broad spectrum. Here, we propose and show that tightly packed fabric of identical dielectric nanopillar waveguides with continuously-tuned inter-coupling distances make excellent and complete achromatic metasurface elements. This architecture enables the scatterers to interact with the incoming wave extremely efficiently. As a proof-of-concept demonstration, we showed an achromatic cylindrical metalens, constructed from strongly coupled dielectric nanopillars of a single geometry as continuously-set phase elements in a 'meta-atomless' fashion, working in the entirety of 400-700 nm band. This metalens achieves over 85 percent focusing efficiency across this whole spectral range. To combat polarization sensitivity, we used hexagonally stacked nanopillars to build up a polarization-independent scatterer library. Finally, a circular metalens with polarization-independent operation and achromatic focusing was obtained. This is a paradigm shift in making an achromatic metasurface architecture by wovening identical nanopillars coupled into an irregular lattice constructed via careful tuning.

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