Z. Fei, A. S. Rodin, G. O. Andreev, W. Bao, A. S. McLeod, M. Wagner, L. M. Zhang, Z. Zhao, G. Dominguez, M. Thiemens, M. M. Fogler, A. H. Castro-Neto, C. N. Lau, F. Keilmann, D. N. Basov
Surface plasmons are collective oscillations of electrons in metals or
semiconductors enabling confinement and control of electromagnetic energy at
subwavelength scales. Rapid progress in plasmonics has largely relied on
advances in device nano-fabrication, whereas less attention has been paid to
the tunable properties of plasmonic media. One such medium-graphene-is amenable
to convenient tuning of its electronic and optical properties with gate
voltage. Through infrared nano-imaging we explicitly show that common
graphene/SiO2/Si back-gated structures support propagating surface plasmons.
The wavelength of graphene plasmons is of the order of 200 nm at
technologically relevant infrared frequencies, with a propagation length
several times this distance. We have succeeded in altering both the amplitude
and wavelength of these plasmons by gate voltage. We investigated losses in
graphene using plasmon interferometry: by exploring real space profiles of
plasmon standing waves formed between the tip of our nano-probe and edges of
the samples. Plasmon dissipation quantified through this analysis is linked to
the exotic electrodynamics of graphene. Standard plasmonic figures of merits of
our tunable graphene devices surpass that of common metal-based structures.
View original:
http://arxiv.org/abs/1202.4993
No comments:
Post a Comment