Giant plasmonically induced circular conversion dichroism in an anisotropic golden slit grating filled by a chiral medium

Abstract

We report the giant plasmonically induced (PI) circular conversion dichroism in transmission $(\mathrm{CC}{\mathrm{D}}_{T})$ and PI-unconverted CD effect $(\mathrm{unCC}{\mathrm{D}}_{R})$ in reflection from the golden slit grating filled by chiral medium (GSGCM). The $\mathrm{CC}{\mathrm{D}}_{T}$ and $\mathrm{unCC}{\mathrm{D}}_{R}$ are the differences between the off-diagonal elements in transmission matrix and diagonal elements in reflection matrix, respectively, and originate from both the chirality and anisotropy. Our research indicates that the $\mathrm{PI}\ensuremath{-}\mathrm{CC}{\mathrm{D}}_{T}$ and PI-$\mathrm{unCC}{\mathrm{D}}_{R}$ in the plasmonic resonance wave band come from the coupling between the inherent chiroptical resonance of chiral medium and the plasmonic resonance of the golden slit grating, where the real part of chiral parameter $\ensuremath{\xi}$ from chiral medium plays a main role in the coupling process. The isotropic chiral medium slab, the anisotropic chiral medium grating, the golden slit grating, and the GSGCM have been rigorously investigated in this work. Our research clearly reveals the difference of PI-chiroptical effect between the anisotropic and isotropic system, and will find potential applications in biosensor and nanophotonic devices.