Tunable optical chirality in a metamaterial platform with off-resonantly coupled metal-dielectric components

Here we present a tunable chiral metamaterial platform that incorporates both metal and dielectric components, where the sign and magnitude of the circular dichroism (CD) response depend on the refractive index of the dielectric component. Using finite-difference time-domain simulations, we show that non-resonant scattering interactions between the components of the system reverse the sign of the CD signal by changing the dissymmetry in absorption of circularly polarized light by the individual plasmonic components of the system. The platform exhibits tunable CD signal regardless of the shape and dimension of the dielectric scatterer, and the magnitude of the CD signal is enhanced by improving the scattering cross section of the dielectric structure. Finally, we show that the structure can be modified to incorporate other materials without diminishing the reversal in dissymmetry in transmission. These results indicate that controlled, off-resonant interactions between different materials in chiral metamaterials may be used to create tailored and tunable chiral platforms.