Abstract-Tunable terahertz radiation from graphene induced by moving electrons

http://eprintweb.org/S/article/cond-mat/1402.2829

T. R. Zhan, D. Z. Han, X. H. Hu, X. H. Liu, S. T. Chui and J. Zi

Department of Physics, Key laboratory of Micro and Nano Photonic Structures (Ministry of Education), and Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, P. R. China Department of Applied Physics, College of Physics, Chongqing University, Chongqing 400044, P. R. China Bartol Research Institute, University of Delaware, Newark, Delaware 19716, USA Department of Materials Science and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, P. R. China

Received. 12 February 2014  Last updated. 12 February 2014

Abstract. Based on a structure consisting of a single graphene layer situated on a periodic dielectric grating, we show theoretically that intense terahertz (THz) radiations can be generated by an electron bunch moving atop the graphene layer. The underlying physics lies in the fact that a moving electron bunch with rather low electron energy ($sim$1 keV) can efficiently excite graphene plasmons (GPs) of THz frequencies with a strong confinement of near-fields. GPs can be further scattered into free space by the grating for those satisfying the phase matching condition. The radiation patterns can be controlled by varying the velocity of the moving electrons. Importantly, the radiation frequencies can be tuned by varying the Fermi level of the graphene layer, offering tunable THz radiations that can cover a wide frequency range. Our results could pave the way toward developing tunable and miniature THz radiation sources based on graphene.