Strong coupling of plasmonic waves in graphene for light confinement

Abstract

The interplay between light and matter is highly required in many fundamental processes and optical devices. Herein, a hybrid graphene-based coupling system in the far-infrared range is proposed to investigate effective light confinement. In our system, the coupling of localized surface plasmons (LSPs) in graphene nanoribbons and Tamm surface plasmons (TSP) in a graphene sheet produces a hybrid dual-band absorption. This property is numerically verified by full electromagnetic simulations and analytically calculated by the rigorous coupled wave theory (RCWA). The hybrid nature of the two optical modes reflected by coupled oscillator model is discussed carefully, and the influences of incident angle and the geometric parameter on the coupling system are also analyzed. We have found that the coupling strength of the hybrid optical mode can be manipulated flexibly by the incident angle and the geometric parameter. Additionally, the group time delay of the light has also been considered, and calculated values as high as 114 ps. This work offers a new paradigm for tunable light-graphene interaction, and facilitates the design of slow light devices in the far-infrared spectral band.