One-dimensional chirality: strong optical activity in epsilon-near-zero metamaterials

TL;DR

This paper demonstrates that one-dimensional patterned composites can exhibit electromagnetic chirality and strong optical activity, especially in epsilon-near-zero regimes, despite being geometrically achiral.

Contribution

It reveals that 1D systems can display chirality and optical activity, with a theoretical analysis of bi-anisotropic responses in multilayered metamaterials.

Findings

1D chiral metamaterials support optical activity.

Optical activity is dramatically enhanced in epsilon-near-zero regimes.

Magneto-electric coupling becomes dominant in these conditions.

Abstract

We suggest that electromagnetic chirality, generally displayed by 3D or 2D complex chiral structures, can occur in 1D patterned composites whose components are achiral. This feature is highly unexpected in a 1D system which is geometrically achiral since its mirror image can always be superposed onto it by a 180 deg rotation. We analytically evaluate from first principles the bi-anisotropic response of multilayered metamaterials and we show that the chiral tensor is not vanishing if the system is geometrically one-dimensional chiral, i.e. its mirror image can not be superposed onto it by using translations without resorting to rotations. As a signature of 1D chirality, we show that 1D chiral metamaterials support optical activity and we prove that this phenomenon undergoes a dramatic non-resonant enhancement in the epsilon-near-zero regime where the magneto-electric coupling can become dominant in the constitutive relations.