Possible implementation of epsilon-near-zero metamaterials working at optical frequencies
- 作者：Alessio Monti ; amonti@uniroma3.it ; Filiberto Bilotti ; Alessandro Toscano ; Lucio Vegni
- 关键词：Optical metamaterials ; Epsilon-near-zero metamaterials ; Core-shell nano-spheres
- 刊名：Optics Communications
- 出版年：2012
- 期刊代码：50_00304018
- 类别：ph
- 出版时间：15 July, 2012
- 卷：285
- 期：16
- 页码：3412-3418
- 文件大小：1768 K
摘要
Metamaterials (MTMs) exhibiting a near-zero real part of the permittivity function in a given frequency range have been demonstrated to be useful in several application fields, including field localization and focusing. So far, however, the realistic implementations of such materials working at optical frequencies and exhibiting a reasonable level of losses are rare. In this work, we propose a possible implementation of optical epsilon-near-zero (ENZ) MTMs based on the employment of an array of core-shell nano-spheres embedded in a dielectric medium. The core of the nano-spheres and the host medium are both made of silica, while the shell is formed by a plasmonic material (i.e. silver). Using classical homogenization formulas, we show that it is possible to design the array in such a way to exhibit near-zero values of the effective real permittivity with relatively low losses at optical frequencies. These results are supported and confirmed by proper full-wave simulations and design examples.