Chiral optical properties of metasurfaces comprised of chiral media: effects of geometric and material chirality

We deconvolute the distinct and sometimes competing effects of geometric and material chirality in metastructures created from materials that are intrinsically chiral. We find that overlapping Mie-like resonances in nanodisk arrays leads to 6-fold CD enhancement compared to a uniform film. Furthermore, making the medium chiral does not necessarily increase CD; enhancement depends on the magnitude of the Pasteur parameter and its real and imaginary components. Finally, to demonstrate how geometric and material chirality can be combined, we design a geometrically chiral meta-atom out of chiral media and observe over 9-fold enhancement in both CD and g-factor compared to a metasurface comprised of achiral material.