Structure-specific chiroptical responses of hollow gold nanoprisms.

Chiroptical responses of plasmonic chiral nanostructures can be controllably tuned by judicious tailoring of their structural parameters. In this article, the chiroptical properties of a newly designed plasmon-supporting nanostructure, chiral hollow gold nanoprisms (HGNs), has been numerically investigated in detail. The most compelling observation is that the CD response and the dissymmetry factor (g, which is a measure of the strength of chiroptical responses) of the chiral HGNs are large and at the same time, highly structure-specific. Also, we observed finite CD activity not only in absorption and scattering but also in the extinction spectra, which is a signature of a typical 3D chiral structure. We show that the chiroptical responses of HGNs can be exponentially enhanced simply by controlling the cavity-position or cavity size. Our results reveal that the structure-specific chiroptical response is a result of structure-dependent interplay between the non-radiative (Ohmic) and radiative losses. We also show that the CD intensity of a suitably designed chiral HGN is higher than other nanoscale metasurfaces of comparable volume. The insights obtained from this comprehensive study assert that this unique chiral nanostructure has great potential for being used in numerous applications.