Circular Dichroism Enhancement in Plasmonic Nanorod Metamaterials

TL;DR

This paper demonstrates that plasmonic nanorod metamaterials can significantly enhance the circular dichroism response of embedded chiral materials, enabling better optical activity characterization.

Contribution

It introduces a novel nanorod metamaterial structure that enhances or suppresses optical activity, offering a new approach for chiroptical studies.

Findings

Enhanced circular dichroism in chiral nanocrystals within nanorod metamaterials

Achiral nanorod structures can tailor optical activity responses

Potential for improved molecular and nanocrystal characterization

Abstract

Optical activity is a fundamental phenomenon originating from the chiral nature of crystals and molecules. While intrinsic chiroptical responses of ordinary chiral materials to circularly polarized light are relatively weak, they can be enhanced by specially tailored nanostructures. Here, nanorod metamaterials, comprising a dense array of vertically aligned gold nanorods, is shown to provide significant enhancement of the circular dichroism response of an embedded material. A nanorod composite, acting as an artificial uniaxial crystal, is filled with chiral mercury sulfide nanocrystals embedded in a transparent polymer. The nanorod based metamaterial, being inherently achiral, enables optical activity enhancement or suppression. Unique properties of inherently achiral structures to tailor optical activities pave a way for flexible characterization of optical activity of molecules and nanocrystal-based compounds.