Semiconductor-Metal-Semiconductor Core-Multishell Nanowires as Negative-Index Metamaterial in Visible Domain
Semiconductor-Metal-Semiconductor Core-Multishell Nanowires as Negative-Index Metamaterial in Visible Domain
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DOI：
10.1038/srep04931
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发表时间：
2014-05
影响因子：
4.6
通讯作者：
Sarath Ramadurgam;Chen Yang
中科院分区：
文献类型：
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作者：
Sarath Ramadurgam;Chen Yang
具有负折射和相位反转特性的负折射率超材料（NIMs），特别是在可见光范围内，由于其在隐身、传感和亚衍射极限成像方面的潜在应用，在过去十年中引起了相当大的关注。NIM通常通过排列具有频谱重叠的磁和电共振的亚波长纳米结构（元原子）来实现。到目前为止，大多数设计都使用缩小谐振元件的比例，并使用具有合适光学常数的材料来获得可见光范围内的NIM。然而，由于大多数金属和半导体的吸收造成的巨大损耗以及由于结垢导致的与光的耦合减少，对实现低损耗NIM提出了挑战。在这里，我们采用等离子体杂化在半导体-金属-半导体核-多壳（CMS）纳米线中作为一种独特的方法来设计低损耗、各向同性和偏振依赖的可见光范围内的NIM。基于数值模拟，我们证明了代表性的Si-Ag-Si CMS纳米线NIM在650 nm处的有效折射率为- 1，性能值（FOM）为17，而GaP-Ag-GaP CMS纳米线NIM在590 nm处的折射率为- 1，FOM为25。
Negative-index metamaterials (NIMs) exhibiting both negative refraction as well as phase reversal, particularly in the visible range, have drawn considerable attention in the past decade due to their potential applications in cloaking, sensing and sub-diffraction-limit imaging. NIM are often realized by arraying sub-wavelength nanostructures (meta-atoms) exhibiting spectrally overlapped magnetic and electric resonances. Most designs so far use scaling down of the resonant elements and employ materials with the right optical constants to obtain NIM in the visible range. However, large losses due to absorption in most metals and semiconductors as well as reduced coupling with light due to scaling pose a challenge to achieving low-loss NIM. Here, we employ plasmon hybridization in semiconductor-metal-semiconductor core-multishell (CMS) nanowires as a unique approach to design low loss, isotropic and polarization dependant NIM in the visible range. Based on numerical simulations, we demonstrate an effective refractive index of −1 and a figure of merit (FOM) of 17 at 650 nm for a representative Si-Ag-Si CMS nanowire NIM and a refractive index of −1, FOM of 25 at 590 nm for a GaP-Ag-GaP CMS nanowire NIM.