Fig. 3. (a) Comparative optical response and near-field distributions for three substrate configurations: flat graphene on SiO2 disks (red curves), flat graphene on SiO2 nanospheres (blue curves), and corrugated graphene on SiO2 nanospheres (black curves) for sphere diameters Ds = 60, 90, and 120 nm. The left panels present the simulated absorption spectra, highlighting the emergence of distinct plasmonic modes (I–III) for each configuration and the SiO2 phonon band. The right panels show the corresponding normalized electric-field intensity distributions |E|/|E0| for each mode at Ds = 120 nm for (b) flat graphene on SiO2 disks, (c) flat graphene on SiO2 nanospheres, and (d) corrugated graphene on SiO2 nanospheres. The corrugated graphene reveals substantially stronger and spectrally sharper plasmonic resonances compared to flat-graphene configurations, with near-field enhancement and photoabsorption intensity approaching an order of magnitude higher.
