一种折射率近零超材料的设计、制作和表征

摘要

Metamaterials made of artificial structures can realize exotic characteristics that natural materials do not possess. Electromagnetic metamaterials, a new and interdisciplinary field, have become one of the hottest topics both in theoretical exploration and experimental verification in recent years. Index-near-zero metamaterials have attracted scientists’ attention as well as single negative or double negative metamaterials because of their widely applications in optical cloaking , radar antenna and military stealth. In this paper, we design and fabricate a type of microwave metamaterials with effective refractive index ranging from 0 to 1, based on the H-fractal structures. We obtain the experimental refractive index spectra of the H-fractal metamaterials by measuring their transmissions and reflections in microwave waveguide transmission line, which proves the metamaterials with refractive index near zero. Our high-performance H-fractal metamaterials provide a designing platform for realizing various index-near-zero transformation optics devices such as Inside-out Eaton Lens.%利用人工结构制成的超材料能够实现天然材料所不具备的特性，电磁超材料作为一个新兴、多学科交叉领域，在理论探究和实验证明上都已成为近年来科学研究的热点之一，除单负和双负材料之外，电磁参数近零的超材料因其在光学隐身、天线雷达、军事等方面的应用也受到科学家的广泛关注。本文利用共振的H分形结构设计制作了在微波频段下折射率分布在[0，1]之间的微波超材料，而且利用微波波导传输线对多种变化尺度的晶胞结构进行电磁参数的测量，得到了每种晶胞结构对应的X波段折射率频谱，通过研究晶胞结构单元的等效电磁参数实现了一种折射率近零超材料，从而为实现近零折射率分布的变换光学器件如Inside-out Eaton Lens的实验研制提供了材料选择。