Engineering high-performance dielectric chiral shells with enhanced chiral fields for sensitive chiral biosensor

Chiral metamaterials have been a topic of significant research interest in recent years due to their potential for various applications in nanophotonic devices and chiral biosensors. However, the intrinsic Ohmic loss in surface plasmonic resonance has limited their practical use, resulting in large light dissipation and weak chiroptical resonance. Here, we report on the development of high-performance dielectric chiral shells (DCS) through a two-step Si deposition process on a self-assembled micro-sphere monolayer. The form DCS sample completely overcomes the cancelation effect originated from the disorder property of the micro-sphere monolayer in macro-scale, and at a wavelength of approximately 710 nm, the measured optimal chiral signal (g-factor) and transmittance can reach up to 0.7 and 0.3, respectively. The strong chiroptical effect comes from the asymmetric circular displacement currents (i.e., magnetic modes) enabled by the specific shell geometry. The chiral shell geometry, electromagnetic properties, sensor sensitivity of chiral molecules and figure of merit are systematically investigated. The DCSs demonstrate highly sensitive detection of chiral biomolecules owing to their easily accessible geometry and enhanced uniform chiral field.