Gain assisted and gain functionalized core-shell nanoparticles: a multi-pronged approach to compensate loss in metamaterials

Optical losses in meta-structures based on metal subunits represents a central topic towards the fabrication of metamaterials in the visible range, since most of the extra-ordinary electromagnetic properties expected in these structured systems are shadowed by unavoidable absorptive effects. In this paper we report experimental studies aimed to demonstrate effective chemical and physical approaches to mitigate the radiation damping effect by means of ”gain assisted” and ”gain functionalized” coreshell metal nanospheres selected as metamaterial building blocks. A multiscale strategy has been utilized to compare these two systems, showing that in both cases partial loss compensation can be obtained.