作者: Ye, Dexin; Chang, Kihun; Ran, Lixin; 等.
来源：NATURE COMMUNICATIONS 卷: 5 文献号: 5841 出版年: DEC. 2014
Realizing metamaterials with negative refractive index has been in the center of attention over the past decades, particularly due to some exceptional prospects that materials with such an exotic electromagnetic property can have for and in superlens, cloaking. However, the inevitable loss due to the strongly resonant nature of metamaterials plagues many of their exciting potential applications. To reduce or eliminate the losses a promising way forward has been the strategy to compensate all losses by combining and thus enhancing metamaterials with gain materials. While such claims now clearly have been proven to be feasible on the basis of fundamental theoretical argumentations as well as through several experimental studies demonstrating loss-compensation in negative index materials, the theoretically predicted over-compensation and amplification was still awaiting experimental confirmation. The present work takes this important step forward. Through a combination of full-wave simulation and experimental measurement a specifically fabricated sample of a negative index metamaterial is shown to exhibits a negative refractive index and a net gain. It shows that a stable net gain can be achieved in volumetric negative-index materials, proposing a potential solution for the critical challenge current metamaterials technology faces in practical applications.
