Data for Chiral Optical Properties of Metasurfaces Comprised of Chiral Media: Effects of Geometric and Material Chirality

Abstract

Chiral nanomaterials and metamaterials are the subject of intense recent interest, but the principles that govern their design can be challenging to identify. With the emergence of a host of new chiral molecules and nanocrystals, metamaterials can be created from materials that are intrinsically chiral, potentially enhancing chiroptical properties by combining geometrical and material factors. To take advantage of this, we first need to deconvolute the distinct and sometimes competing effects of geometric and material chirality on chiroptical properties. Here, we investigate the role of the meta-atom geometry, optical resonances, and chirality of the constituent medium on the optical chirality enhancement, circular dichroism (CD), g-factor, and relative transmission of LCP versus RCP light (∆T) in metasurfaces comprised of chiral material. We find that overlapping Mie-like resonances in nanodisk arrays lead to 6-fold CD enhancement compared to a uniform film. Our analysis also suggests that making the medium chiral does not necessarily increase CD or g-factor; enhancement in the CD and optical chirality depend on the magnitude of the Pasteur parameter as well as its real and imaginary components. As a demonstration of how geometric and material chirality can be combined to enhance chiroptical properties, 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. This work systematically investigates different approaches to tailoring a chiral response from nanostructured arrays and provides design rules that can be broadly applied to metastructures comprised of chiral media.