Chiral Infrared Metamaterials for Enhanced Molecular Spectroscopy

Abstract

This thesis presents a computational and experimental study of a chiral metamaterial made up of twisted U-shaped split-ring resonators, designed to function in the mid-infrared part of the electromagnetic spectrum. Both the far-field and near-field response of the metamaterial is investigated, for a number of different geometries and configurations. The metamaterial exhibits high levels of circular dichroism in the far-field and so called "super-chiral" fields in the near-field. These fields are exploited for enhanced vibrational circular dichroism spectroscopy of the chiral amino acid alanine, at a layer thickness and concentration beyond the detection limit of the system without the metamaterial. This is a proof of principle demonstration that could be extended to any chiral molecules possessing the chiral amide band resonances in the future. The insights provided in this thesis pave the way for enhancing the sensitivity of chiral molecular spectroscopy which is highly important in a number of industries including medicinal drug design as well as food science.