Invited Paper
Optical Sensing and Light Modulation with Atomic Scale Systems

Recent experimental [1-5] and theoretical [6-10] advances in the study of graphene plasmons have triggered the search for similar phenomena in other materials that are structured down to the atomic scale, and in particular, alternative 2D crystals [11], noble-metal monolayers [12], and polycyclic aromatic hydrocarbons, which can be regarded as molecular versions of graphene [13]. The number of valence electrons that are engaged in the plasmon excitations of these materials is small compared with those of conventional 3D metallic nanostructures, and consequently, the addition or removal of a comparatively small number of electrons produces sizeable changes in their frequencies and near-field distributions. Graphene in particular has been shown to exhibit a large degree of electrical modulation due to its peculiar electronic band structure, which is characterized by a linear dispersion relation and vanishing of the electron density of states at the Fermi level; few electrons are needed to considerably change the Fermi energy. However, plasmons in graphene have only been observed at mid-infrared and lower frequencies [1-5], and therefore, small molecular structures [13] and atomically thin metals [12] constitute attractive alternatives to achieve fast electro-optical modulation in the visible and near-infrared (vis-NIR) parts of the spectrum. In this presentation, we review different strategies and recent advances in the achievement of strong optical tunability in the vis-NIR using plasmons of atomic-scale materials, as well as their potential application for quantum optics, light manipulation, and sensing.

References

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javier.garciadeabajo@icfo.es