Author(s): Vincent Ginis, Philippe Tassin, Thomas Koschny, and Costas M. Soukoulis

In addition to its extraordinary mechanical, thermal and electrical properties, graphene shows great potential in manipulating electromagnetic fields. One of the main advantages of graphene compared to other materials is the extraordinary tunability of its conductivity, which can be achieved electrically by means of a back gate, or optically through the excitation of photocarriers. Scientists from Belgium, Sweden and the United States demonstrate that this tunability of graphene can be used in a novel setup for the generation of frequency combs. Traditionally, frequency combs are generated using nonlinear materials. The researchers studied the interaction between light and time-dependent graphene sheets, including both dispersion and explicit time-dependence of the conductivity. Based on this model, they demonstrated that frequency combs can be generated without material nonlinearities. Indeed, at terahertz frequencies it is possible to modulate the linear, time-dependent conductivity of graphene to obtain a large variety of frequency combs.

[Phys. Rev. B 91, 161403(R)] Published Wed Apr 08, 2015

http://link.aps.org/doi/10.1103/PhysRevB.91.161403