Graphene Based Terahertz Cavity Plasmon-Polariton in the Presence of Optical Modulation

We present a detailed theoretical study on terahertz (THz) cavity plasmon polariton in graphene embedded in a Fabry–Perot cavity under optical modulation. Based on classical electromagnetic theory, we obtain analytically the dispersion equation for cavity plasmon polariton (CPP) modes. The obtained results show the existence of two types of CPP modes in THz range. One can be referred as Fabry–Perot-like modes and another as surface-plasmon-like modes (SPLMs). Interestingly, the SPLMs can realize notable enhancement of wave localization in comparison with usual graphene plasmons. Moreover, a scheme to modulate the THz CPP modes via visible light irradiation is proposed and examined. We find that the optical pumping can affect rather efficiently the CPP modes via excitation of photon induced carriers. These important theoretical findings indicate that the CPP can be applied in all-optical tunable plasmonic devices in THz bandwidth. This paper is relevant to the application of graphene as advanced optical and plasmonic devices.