Synchronous Slow and Fast Light Based on Plasmon-Induced Transparency and Absorption in Dual Hexagonal Ring Resonators

Slow and fast light effects have many potential applications. In this paper, slow and fast light were obtained synchronously based on plasmon-induced transparency (PIT) and plasmon-induced absorption (PIA). The proposed structure consisted of dual hexagonal ring resonators coupled with two parallel metal-insulator-metal waveguides. The theoretical model established using temporal coupled-mode theory showed that the core–core separation and resonance wavelength detuning between two hexagonal rings were the key factors to PIT and PIA. The finite-difference time-domain simulation results revealed that the structural parameters have an important influence on the transmission characteristics and group indices. Moreover, there was a feasible way for adjusting the slow and fast light effects without changing the geometric dimensions. This proposed structure can provide a way toward controlling the velocity of light in highly integrated devices.