Circular Dichroism Enhancement Induced by Strong Coupling and Weak Coupling in Metal Disk-Chiral TDBCs-Metal Disk Structure.

We theoretically investigate a circular dichroism (CD) spectrum enhancement in a silver disk-chiral TDBCs-silver disk structure in the strong coupling regime. Chiral TDBCs are sandwiched between two Ag disks. Absorption and scattering spectra are obtained by the finite difference time domain method. Both absorption and scattering CD spectra are also used to describe the chirality of our proposed structure. Chirality of TDBCs is amplified by localized surface plasmons (LSPs) excited in two Ag disk structure. Our results show that the chirality of TDBCs is amplified by the LSPs as 300 times for the absorption spectrum (150 times for the scattering spectrum) as the one of only TDBCs in the strong coupling regime. In the strong coupling regime, there is an optimal suit of parameters to make maximum of CD spectrum largest enhancement in the absorption spectrum. The enhancement factor of CD spectrum in the strong coupling regime is much larger than the one in the weak coupling regime. It is because that the stacking disk structure provides a strong confinement of the electric field to coupling with chiral TDBCs near the resonant wavelengths of TDBCs. Due to the large amplification of CD spectrum, our proposed structure provides a new method to detect the chirality of TDBCs in experiment. [ABSTRACT FROM AUTHOR]