CDDA: extension and analysis of the discrete dipole approximation for chiral systems

Abstract

Discrete dipole approximation (DDA) is a computational method broadly used to solve light scattering problems. In this work, we propose an extension of DDA that we call Chiral-DDA (CDDA), to study light-chiral matter interactions with the capability of describing the underlying physics behind. Here, CDDA is used to solve and analyze the interaction of a nanoantenna (either metallic or dielectric) with a chiral molecule located in its near field at different positions. Our method allowed to relate near field interactions with far field spectral response of the system, elucidating the role that the nanoantenna electric and magnetic polarizabilities play in the coupling with a chiral molecule. In general, this is not straightforward with other methods. We believe that CDDA has the potential to help researchers revealing some of the still unclear mechanisms responsible for the chiral signal enhancements induced by nanoantennas.

Near‐Field Coupling Induced Less Chiral Responses in Chiral Metamaterials for Surface‐Enhanced Vibrational Circular Dichroism

“…[31][32][33][34] Although these works either theoretically or experimentally reported an enhanced molecular signal, there lacks an intuitive comparison of performances between the achiral and chiral sensors. Besides, previous works have studied the near-field interactions between chiral molecules and nanoantennas, [35] providing theoretical evidence for the mechanisms of chiral light-matter interactions. However, direct evidence showing the relation between enhanced molecular signal and the chiral near-field enhancement is missing.…”

Nanophotonic Chirality Transfer to Dielectric Mie Resonators

“…Importantly, regardless of the material platform for nanophotonic chiral sensing, the CD of the combined system of molecules and nanostructures will most generally arise from the combined effects of the optical chirality and chirality transfer mechanisms. However, most studies thus far have focused on only one mechanism without considering both consistently, which has been a source of the mismatch between experimental results and theoretical predictions. − Therefore, an incomplete understanding of the underlying physics responsible for chirality transfer still limits the rational design of nanophotonic platforms for chiral sensing. − …”