Chirality from shadowing deposited metallic nanostructures

• Chiral nanostructures are fabricated for the visible range using a shadowing vapor deposition method on asymmetric columnar arrays.
• Large transmission difference in the visible range is observed for circularly polarized incident light.
• The chirality can be tuned by the asymmetry of the nanostructures providing an extra degree of freedom to achieve large chiral property.

We report chiral optical responses of metallic quasi-3D nanostructures fabricated by shadowing vapour deposition of Ag on “L”- and “mirror L”-shaped nanoscale dielectric columnar arrays. Large transmission difference between left- and right-handed circularly polarized incident light in the visible range is observed. Furthermore, the difference could be tuned by the indentation parameter for the “L”- and “mirror L”-shaped Ag/PMMA columnar arrays. Numerical simulations for the nanostructures show good agreement with the experimental results, suggesting that the chiral optical responses of the shadowing deposited nanostructure are dominated by 3D chirality.