Terahertz angle-insensitive 90° polarization rotator using chiral metamaterial

We design and study a kind of gammadion-like chiral metamaterial (CMM), which uniaxially exhibits exceedingly strong optical activity and circular dichroism. The optical activity obtained by the proposed CMM rises to about 2280°/λ, which is much larger than that of the previously reported planar designs. Due to the giant chirality, the present CMM can realize negative refractive index easily at the resonant frequencies. The most fascinating property of the present CMM is that it can function as a 90° polarization rotator for wide incident angles, thereby holding great promise for future devices.