A comparison study of the Born-Kuhn model and the finite-difference-time-domain calculations on stacked plasmonic nanorods

Abstract A detailed analysis of the Born-Kuhn model for two coupled oscillators and comparison to the chiral optical properties of the corner-stacked plasmonic nanorods (CSPN) have been investigated. Based on the normalized coupling constant c (= coupling frequency ω c /resonance frequency ω 0 ) and the damping constant g (= dissipation γ/ω 0 ), the chiral optical response of the Born-Kuhn model could be significantly different, and the c-g space can be divided into two phase regions, a weak coupling and a strong coupling region. Once the c and g parameters are extracted from CSPN structures based on finite-difference time domain (FDTD) calculations, the Born-Kuhn model can be directly applied to predict the chiral plasmonic response of the CSPNs. In particularly, at c=√g, the Born-Kuhn model suggests the strongest optical rotation dispersion while stronger circular dichroism occurs with a small g and a large c. These predictions have been confirmed by the FDTD calculations of CSPN structures. The detailed analysis of the Born-Kuhn model and the use of the model to direct fit the optical property of CSPNs demonstrate that the Born-Kuhn model is a very versatile class model to predict the chiral response of a chiral plasmonic structure or help to design and optimize a specific chiral plasmonic structure for a specific application.