Figure 1.

$\sigma$ (from Equations (2) and (3)), ${ϵ}_r$ (from Equation (4)), and $n_{sp}$ (from Equation (5)) at sub-THz (a), THz to mid-IR (b), and near-IR frequencies (c). $\mu =1$ m${}^2/\mathrm{Vs}$, $d=0.35\mathrm{nm}$, ${ϵ}_{av}=1$. The thick lines are for $E_F=0.2\mathrm{eV}$, and the thin lines are for $E_F=0.25\mathrm{eV}$. The solid lines are the real parts, and the dash lines are the imaginary parts. The key material properties of graphene are summarized in (d) at different frequencies.