Figure 1
From: Tunable graphene-based hybrid plasmonic modulators for subwavelength confinement
Plasmon dispersion of monolayer graphene when the graphene is doped (For clarify, here we use highly doped graphene with E F = 1 eV.), as illustrated by the photon-energy and parallel-wave-vector dependence of the imaginary part of reflection coefficient for p-polarization. Interband absorption produces strong plasmon quenching when the photon energy exceeds 2E F (i.e., above the yellow dash line).
