Three-dimensional artificial double helices with high negative refractive index

Abstract

Chirality can be manipulated in multilayer three-dimensional helices. Multiple backbone helices can be effectively designed and fabricated, preserving their unique electromagnetic properties of chiral metamaterials. Chirality is boosted in double helices. The chirality index is four times higher than in single helices. Based on the extreme chirality, the effective refractive index of the 3D double helices is proved to be negative, with low loss.