Ultra-thin, planar, Babinet-inverted plasmonic metalenses
Ultra-thin, planar, Babinet-inverted plasmonic metalenses
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DOI：
10.1038/lsa.2013.28
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发表时间：
2013-04-01
影响因子：
19.4
通讯作者：
Shalaev, Vladimir M.
中科院分区：
文献类型：
--
作者：
Ni, Xingjie;Ishii, Satoshi;Shalaev, Vladimir M.
我们实验演示了用30 nm厚的同心穿孔金膜制成的超薄平面亚表面对可见光的聚焦。穿孔的纳米空洞--巴比内--倒置(互补)纳米天线--产生离散的相移，并形成所需的交叉极化散射光的波前。我们的互补纳米天线设计的信噪比比以前的金属纳米天线设计至少高出一个数量级。我们首先研究了我们具有极强聚焦能力的概念验证‘金属透镜’：用一个直径为4微米的透镜对波长为676 nm的光进行实验，仅在2.5微米的距离内实现聚焦。然后，我们使用其中一种“金属透镜”来扩展我们的工作，并实现波长可控的焦距。透镜的光学特性证实，将入射波长从676 nm切换到476 nm会将焦距从7 mm改变到10 mm，这为在微米级的小区域内调谐和空间分离不同波长的光开辟了新的机会。所有建议的设计都可以嵌入到芯片上或光纤末端。这些设计也都适用于入射光的两个正交的线性偏振。
We experimentally demonstrate the focusing of visible light with ultra-thin, planar metasurfaces made of concentrically perforated, 30-nm-thick gold films. The perforated nano-voids-Babinet-inverted (complementary) nano-antennas-create discrete phase shifts and form a desired wavefront of cross-polarized, scattered light. The signal-to-noise ratio in our complementary nano-antenna design is at least one order of magnitude higher than in previous metallic nano-antenna designs. We first study our proof-of-concept 'metalens' with extremely strong focusing ability: focusing at a distance of only 2.5 mu m is achieved experimentally with a 4-mu m-diameter lens for light at a wavelength of 676 nm. We then extend our work with one of these 'metalenses' and achieve a wavelength-controllable focal length. Optical characterization of the lens confirms that switching the incident wavelength from 676 to 476 nm changes the focal length from 7 to 10 mm, which opens up new opportunities for tuning and spatially separating light at different wavelengths within small, micrometer-scale areas. All the proposed designs can be embedded on-chip or at the end of an optical fiber. The designs also all work for two orthogonal, linear polarizations of incident light.