Graphene Plasmonics: Challenges and Opportunities

Abstract

Graphene plasmons are rapidly emerging as a viable tool for fast electrical manipulation of light. The prospects for applications to electro-optical modulation, optical sensing, quantum plasmonics, light harvesting, spectral photometry, and tunable lighting at the nanoscale are further stimulated by the relatively low level of losses and high degree of spatial confinement that characterize these excitations compared with conventional plasmonic materials. We start with a general description of the plasmons in extended graphene, followed by analytical methods that lead to reasonably accurate estimates of both the plasmon energies and the strengths of coupling to external light in graphene nanostructures, including graphene ribbons. We discuss several possible strategies to extend these plasmons towards the visible and near infrared, including a reduction in the size of the graphene structures and an increase in the level of doping. Specifically, we discuss plasmons in narrow ribbons and molecular-size graphene structures. We further formulate prescriptions based on geometry to increase the level of electrostatic doping without causing electrical breakdown. Results are also presented for plasmons in highly-doped single-wall carbon nanotubes, which exhibit similar characteristics as narrow ribbons and show a relatively small dependence on the chirality of the tubes. We further discuss perfect light absorption by a single-atom carbon layer, which we illustrate by investigating arrays of ribbons using fully analytical expressions. Finally, we explore the possibility of exploiting optically pumped transient plasmons in graphene, whereby the optically heated graphene valence band can sustain collective plasmon oscillations similar to those of highly doped graphene, and well-defined during the picosecond time window over which the electron is at an elevated temperature.Comment: 21 pages, 9 figures, comprehensive and tutorial description of graphene plasmonics, lots of analytical results that are easy to compute, proposed experiments, et

Plasmonics in atomically thin materials

“…Consequently, this condition can be easily met using silver atomic monolayers, and also with multilayers of either gold or silver. Incidentally, similar results are obtained for ribbon arrays of period a [45]. Then, the condition (8) remains unchanged, with A/A c = D/a, where D is the ribbon width.…”

“…(A6) in the ω → 0 limit (i.e., when the island behaves as a perfect conductor, so that ω/σ → 0). Without loss of generality, we can consider a freestanding island (n eff = 1), so we have Interestingly, for these types of structures and polarizations, we find one single mode j = p to be dominant and to absorb most of the weight in the above sums [45]. More precisely, this is the lowest-order dipole plasmon.…”

Ultrafast Multiphoton Thermionic Photoemission from Graphite

“…As electricity emerged from the laboratory, the first optoelectronic devices, incandescent light bulbs, converted electricity to light by Ohmic heating of carriers within graphitized bamboo fibers. More recently, graphene has been identified as a material with remarkable optical and electronic properties for numerous applications [9][10][11] and has sparked interest in novel physical properties of two-dimensional (2D) materials [12,13]. As a semimetal, under linear optical excitation, graphene is nonemissive, but under nonlinear optical or electrical stimulation, it can emit both intense incandescence characterized by blackbody radiation temperatures in excess of 3000 K and broadband coherent radiation [14][15][16][17].…”

Far Infrared Synchrotron Near-Field Nanoimaging and Nanospectroscopy

“…The promise of tunable graphene plasmonics is already being exploited for the development of novel nano-photonics applications from visible to THz frequencies [39]. As an atomically thin layer, there is great interest in coupling graphene plasmons to other vibrations in adjacent layers or substrates, given its high sensitivity to the immediate environment [40].…”