Achieving maximum scattering circular dichroism through the excitation of anapole states within chiral Mie nanospheres

Abstract

The chirality-dependent asymmetric light-matter interaction can be enhanced using various artificial photonic structures as well as engineered incident field. Compared with chiral photonic structures, the engineered optical field is less explored and recently recognized as a new regime in tailoring light-matter interaction. In this work, we demonstrate that weakly chiral spheres can exhibit the maximum scattering circular dichroism (CD) by tailoring the incident field to construct chirality-sensitive anapole states. By considering the chiral terms radiated from Mie nanospheres as perturbation, a multiscattering model is established to predict the chiroptical Mie scattering response of these nanospheres. This model provides a specific guideline to tailor the incident field to realize the upper limit of the achievable scattering CD.