Phonon-Like Plasmonic Resonances in a Finite Number of Graphene Nanoribbons

Graphene plasmon polaritons excited in individual and periodic nanoribbons microstructures have attracted enormous attention in plasmonics due to their complicated edge effect and excellent tunability. As the distance between neighboring graphene nanoribbons becomes small enough, the strong coupling between the plasmons in individual nanoribbons produces collective oscillations of surface plasmons in a graphene nanoribbons array, the dispersion of which behaves as phonons in a solid, that is, the phonon-like plasmonic resonance mode. In this paper, such a phonon-like plasmonic resonance is theoretically demonstrated in a finite number of graphene nanoribbons deposited on a silicon substrate. Based on the classical LC circuit model, an analytical dispersion relation is obtained to explain the simulated results. Furthermore, an electrically controlled plasmonic switch is proposed with a high performance based on the plasmonic phonon-like resonance theory. The work provides the building blocks to construct graphene plasmonic circuits for future compact optoelectronic devices.