Plasmon-induced strong interaction between chiral molecules and orbital angular momentum of light

TL;DR

This paper proposes a theoretical method to study and potentially observe the strong interaction between chiral molecules and optical orbital angular momentum mediated by plasmon resonances, explaining previous experimental challenges.

Contribution

It introduces a T-matrix approach to analyze chiral-OAM interactions and suggests an experimental scheme to detect these interactions via plasmon resonance excitation.

Findings

Strong interaction can be induced by plasmon resonances.

OAM dichroism signals can be positive or negative depending on nanocomposite positions.

Cancellation effects explain why previous experiments did not observe the interaction.

Abstract

Whether or not chiral interaction exists between the optical orbital angular momentum (OAM) and a chiral molecule remains unanswered. So far, such an interaction has not been observed experimentally. Here we present a T-matrix method to study the interaction between optical OAM and the chiral molecule in a cluster of nanoparticles. We find that strong interaction between the chiral molecule and OAM can be induced by the excitation of plasmon resonances. An experimental scheme to observe such an interaction has been proposed. Furthermore, we have found that the signal of the OAM dichroism can be either positive or negative, depending on the spatial positions of nanocomposites in the cross-sections of OAM beams. The cancellation between positive and negative signals in the spatial average can explain why the interaction has not been observed in former experiments.