Petahertz-frequency plasmons in graphene nanopore and their application to nanoparticle sensing

The Surface Plasmon Resonance (SPR) properties in the petahertz (10^15 Hz) frequency range for monolayer graphene nanosheet and graphene nanopore are investigated using discrete dipole approximation method. We calculate graphene refractive indices by using first-principle density functional theory. The near-field enhancement made by plasmon in these structures is studied by employing finite-difference-time-domain method. For graphene nanosheets, energy of the SPR peak drops with increase in the sheet length. Also, for graphene nanopores smaller than 5 nm in length, increasing the pore diameter decreases energy of the SPR peak and for some length values like 6 nm, this energy value is raised. For larger sheets (e.g., 8 nm), SPR peak is rather unchanged by variations of the pore diameter. The SPR is used to detect nanoscale objects such as gold, silver, copper, rhodium, and aluminium oxide. If nanoscale particles are inserted into the graphene nanopore, 0.195 to 0.474 eV shift in the SPR spectra appears. Type of the presented nanoparticle can be clearly determined by measuring the energy shifts in the SPR spectra. Our results show that petahertz-frequency plasmon in graphene nanopore can be used as a nanoscale-object detection methodology.