Fig. 3. Optical modulation of plasmons in graphene and graphene/metal hybrid systems.

We consider different structures (see insets) with equivalent spatial modulations of the electron temperature, optically imprinted on graphene (panel a, top) and consisting of a series of Gaussian profiles arranged with period P, FWHM w and peak temperature T_max = 8000 K, superimposed on a room temperature background T_min = 300 K; the resulting modulation of the conductivity is shown in the lower plot. b–d Absorbance spectra of two different structures with geometrical parameters P, w, h and spacings s as indicated by the labels; all dielectrics in these structures (yellow regions in the insets) are taken to have a permittivity ε = 2; the graphene Fermi energy is varied in all plots according to the legend in b; spectra reveal pure graphene plasmons in b, graphene-modulated metal-like plasmons in c and graphene acoustic plasmons in d. e–g Electric field distributions in the structures of b–d at the plasmon frequencies indicated by the corresponding spectral points A–D; solid and dashed white lines indicate the graphene and metal interfaces