Active Control and Biosensing Application of Induced Chirality between Symmetric Metal and Graphene Nanostructures

Abstract

Induced circular dichroism (ICD) is found between plasmonic nanostructures and chiral molecules, where at least one of them is chiral. However, it is a great challenge to generate ICD only through achiral structures with the simple coupling model. Here, we demonstrate that ICD is approximately contributed by the cross-electromagnetic coupling between equivalent electric dipole moments and magnetic dipole moments for two achiral plasmon nanostructures. To prove electromagnetic couplings between different wavebands, graphene belts are introduced into plasmon nanostructures composing achiral metal-nanorods with graphene-nanobelt arrays (AMGAs). Results showed that ICD signals are achieved in a near-infrared band of metal resonance and a micron band of graphene resonance. Near-field charge distributions of AMGAs reveal the coupling effect between metal-nanorods and graphene-nanobelts. The handedness of AMGAs can be actively controlled by adjusting the Fermi levels of graphene-nanobelts; the strength and reson...