Superchiral Fields in Nanophotonics

Abstract

Chirality represents the asymmetry of an object or system and is fundamental and ubiquitous in chemistry. Chiral molecules with stereoisomers, such as enantiomers, often exhibit distinct or even opposite biological activities. A critical step in drug development is the rapid and accurate differentiation of enantiomers. Due to its inherent chirality, circularly polarized light (CPL) is used commercially for chiral sensing and detection. Despite the progress, the weak interactions between CPL and chiral molecules make detection equipment extremely bulky and expensive. The construction of superchiral fields in nanophotonic devices can greatly enhance the interaction between chiral light and matter, offering the possibility of detecting chirality in a compact manner. Consequently, superchiral field has been intensively explored in the past decade. This review systematically summarizes the origin and developments of superchiral fields in different plasmonic and dielectric nanostructures, ranging from single nanoparticles to metamolecules and metasurfaces. A novel phenomenon of chiral mode splitting, resulting from enhanced chiral light–matter interaction, is elucidated and discussed as well.