Enhanced circular dichroism of plasmonic system in the strong coupling regime*

Abstract

The circular dichroism (CD) signal of a molecule is usually weak, however, a strong CD signal in optical spectrum is desirable because of its wide range of applications in biosensing, chiral photo detection, and chiral catalysis. In this work, we show that a strong chiral response can be obtained in a hybridized system consisting of an artificial chiral molecule and a nanorod in the strong coupling regime. The artificial chiral molecule is composed of six quantum dots in a helix assembly, and its CD signal arises from internal Coulomb interactions between quantum dots. The CD signal of the hybridized system is highly dependent on the Coulomb interactions and the strong coupling progress through the electromagnetic interactions. We use the coupled oscillator model to analyze strong coupling phenomenon and address that the strong coupling progress can amplify the CD signal. This work provides a scenario for designing new plasmonic nanostructures with a strong chiral optical response.