Plasmon induced transparency and absorption in bright-bright mode coupling metamaterials: A radiating two-oscillator model analysis

Abstract

A radiating two-oscillator model is developed to describe plasmon-induced transparency (PIT) and absorption (PIA) spectral responses in a two-bright mode coupling system, from which the analytical expressions of the scattering parameters are derived. To verify the validity of the model, the scattering parameters are used to fit with corresponding numerical data obtained from finite difference time domain simulations by using a simple planar structure. The transmission and reflection spectra can be well reproduced simultaneously, indicating that the model is effective and convenient for describing two-bright mode coupling. By analyzing the transmission phase of the bright modes, the physical regime behind the PIT effect is revealed. Successful reproduction of group delay shows that the model can be used in analyzing slow light effects. In addition, a study on resonance detuning and the damping factor indicates that the two parameters should be considered simultaneously in the PIT effect. PIA-like phenomenon can also be achieved in the system but with a smaller detuning compared with the PIT effect. The results obtained here may be useful for designing active devices in the future.