The nanoplasmonics community is searching for materials improving the performance of e.g. noble metals and graphene is a promising and intriguing new material, also in this context. Graphene is emphasized for the high electron mobility and its ability to confine plasmon polaritons tightly, thus opening up new avenues for enhanced light-matter interactions. Graphene may also be emphasized by being tunable, which is a novelty for electro-optical applications. We propose to study experimentally graphene-plasmon polaritons in nano-engineered geometries, using both optical excitation and electron energy loss spectroscopy (EELS), supported strongly by theory activities addressing both microscopic and semiclassical frameworks for the optical response of the graphene plasmons. 

 asger figur wp3 (b385).jpg
Figure: In a freely suspended graphene sheet the graphene-plasmon polaritons are non-radiation, i.e. without any coupling to the far-field due to a momentum mismatch with the free-space electromagnetic field. The momentum mismatch may be overcome when graphene is in proximity to an artificial periodic grating. Panels (a)-(c) schematically illustrate a sphere-array process to fabrication of a two-dimensional subwavelength silicon grating (submicron periodicity), with a subsequent transfer of an atomically thin graphene layer, Panel (d). Panels (e) and (f) show electron micrographs of the resulting structures, while Panel (g) shows an experimental Raman spectrum typical for monolayer graphene.

asger sorth-hvis ny str.jpg

N. Asger Mortensen (Leader)
DTU Fotonik

Graphene plasmonics
24 JANUARY 2021