Designs of Helix Metamaterials for Broadband and High-Transmission Polarization Rotation

Artificial optical activity can be realized using chiral metamaterials, in which chirality is normally implemented with rotationally stacked planar structures. However, such geometries usually suffer from great loss and limited operation bandwidth, which may hinder their usage in many applications. In this study, by incorporating genetic algorithm for geometry optimization, we present designs of helix metamaterials that exhibit high transmission above 95% and a broad bandwidth with low ellipticity. The optical characteristics are described, and the nature behind the high transmission and broad bandwidth is discussed.