Optical Activity of Planar Achiral Metamaterials

TL;DR

This paper demonstrates that non-chiral planar metamaterials can exhibit strong optical activity and circular dichroism, typically associated with chiral structures, and also show negative-index behavior through backward waves.

Contribution

It reveals that achiral planar metamaterials can produce significant optical activity and negative-index effects, challenging the traditional association of these phenomena with chirality.

Findings

Strong resonant optical activity observed

Backward wave indicating negative index

Optical effects achieved without chirality

Abstract

We report that the classical phenomena of optical activity and circular dichroism, which are traditionally associated with chirality (helicity) of organic molecules, proteins and inorganic structures, can be observed in non-chiral artificial media. Intriguingly, our metamaterial structure yields exceptionally strong resonant optical activity, which also leads to the appearance of a backward wave, a characteristic sign of negative-index media.