Abstract

Chiral media interact preferentially with either left- or right-circularly polarized electromagnetic waves, leading to effects including circular dichroism, optical rotation and circular preferential scattering. In this experiment, we revisit Lindman’s famous 1920 experiment linking artificial chiral materials to optical activity and we record the first time-domain measurements of a single-cycle THz pulse transmitted through randomly oriented metallic helices. Time-resolved measurements of co-and cross-polarized components of the transmitted electric field allow the electric field trajectory to be reconstructed and time dynamics of the two circular components to be investigated. For the first time, we show that time dynamics reveal two distinct effects that are separated in time: local preferential circular scattering and collective coupling. These findings are important on furthering our understanding on the analogy between optical activity arising from light interaction with large chiral molecules and that from macroscopic artificial chiral media.