On Negative Index Metamaterial Spacers and Their Unusual Optical   Properties
  We theoretically investigate the possibility of using a metamaterial structure as a spacer, named as metaspacer, which can be integrated with other materials in microfabrication. We show that such metaspacers can provide new optical behaviors that are not possible through conventional spacers. In particular, we investigate negative index metaspacers embedded in fishnet metamaterial structures and compare them with conventional fishnet metamaterial structures. We show that the negative index metaspacer based fishnet structure exhibits intriguing inverted optical response. We also observe that the dependence of the resonance frequency on the geometric parameters is reversed. We conclude with practicality of these metaspacers. 
Muhammad I. Aslam and Durdu \"O. G\"uney
physics.optics