Chiral plasmonic superlattice resonance based on metasurfaces for chiral molecular sensors

Metasurfaces composed of metal nanostructures enhance light-matter interactions at nanoscale due to surface plasmon resonances. However, the distance between units of a metasurface is limited by the resolution and cost of current physical methods, inhibiting the deep study and wide applications of nanophotonics. Currently, plasmonic superlattice structures constructed by the self-assembly of plasmonic nanoparticles provide one way to address this challenging issue. In this study, we design a chiral plasmonic superlattice based on the metasurface of a periodic unit consisting of three discrete chiral Au NRs. The CD spectra of the plasmonic lattice calculated by the Born-Kuhn model agree well with those calculated by COMSOL. Furthermore, we investigate the performance of this type of chiral sensor, focusing on bridging the theoretical relationship between chiral plasmonic lattice resonance and the detection of chiral molecules. The plasmon lattice resonance mode results in the emergence of a narrow linewidth peak within the CD spectrum, significantly enhancing the figure of merit (FOM). The FOM of the molecular sensors based on chiral plasmon lattice resonance is 8.67 times that based on discrete chiral Au NRs. Our results provide insights for the development of nanophotonics and theoretical guidance for the experimental construction of chiral plasmonic sensors with excellent performance.