Integrated Chiral Sensing With Whispering Gallery Mode Microresonators

ABSTRACT Nanophotonic structures offer a compelling solution for detecting the handedness of chiral materials in minute quantities, overcoming a persistent challenge in biochemistry and pharmaceutical research. By enhancing optical chirality, these structures enhance inherently weak chiroptical signals. In this work, we introduce a whispering gallery mode (WGM) microdisk resonator for chiral sensing based on a mode‐shift detection mechanism. We demonstrate an efficient approach to generate strong optical chirality distributions within the resonator by simultaneously exciting two of its fundamental radial modes—quasi‐TE and quasi‐TM—with distinct azimuthal mode numbers. These optical chirality‐enhanced regions on the microcavity surface serve as optimal sites for chiral light‐matter interactions, enabling the handedness of a chiral sample to be transduced into measurable WGM resonance wavelength shifts. We develop a theoretical framework to elucidate the generation of optical chirality in microdisk resonators and employ perturbation theory to model the resonance shift induced by a chiral perturbation in the host medium. Our results offer key insights into detecting handedness in chiral molecules and nanostructures using WGM microresonators as an integrated dielectric platform.