Surface plasmons in graphene and carbon nanotubes

Physics and applications of surface plasmon in graphene and carbon nanotubes are reviewed. The surface plasmon in graphene can be excited by THz electro-magnetic wave. Since the surface plasmon in graphene propagates sufficiently long (> 10 mm) on the surface, we can fabricate a new THz device. The surface plasmon in doped carbon nanotube is observed as a new absorption peak in infrared region. The origin of the surface plasmon in nanotube is understood by inter-subband plasmon whose energy is scaled by the Fermi energy and diameter of the nanotube. In order to understand physics of the surface plasmon, we first discuss resonant conditions of surface plasmon for graphene and nanotube by calculating energy dispersions of the surface plasmon. Then we show some experimental techniques to excite the surface plasmon, in which energy-momentum matching is achieved between a photon and a plasmon. For discussing propagation of the surface plasmon, we define characteristic lengths of propagation and confinement for a surface plasmon. Finally, we give a perspective for the applications of the surface plasmon in graphene and nanotubes. (C) 2020 Elsevier Ltd. All rights reserved.