Graphene nanoelectromagnetics: From radio frequency, terahertz to mid-infrared

Graphene nanoelectromagnetics has recently attracted tremendous research interest, as it merges two vibrant fields of study: plasmonics and nanoelectronics. In the relatively unexplored terahertz (THz) to mid-infrared (MIR) region, the collective oscillation of massless Dirac fermions in graphene can excite the propagating surface charge-density waves (surface plasmon polaritons) tightly confined to the graphene surface. Graphene is the only known material whose equilibrium (nonequilibrium) conductivity can be tuned over a broad range, as a function of its Fermi (quasi-Fermi) level. Hence, the electromagnetic field/wave behavior on a graphene monolayer or a graphene-based nanostructure can be dynamically tuned by chemical doping, electrostatic gating, or photopumping. Such tunable plasmonic properties open tremendous new possibilities in novel THz and infrared (IR) optoelectronic devices with compact size, ultrahigh speed, and low power consumption. In the visible (VIS) region, graphene has high optical transparency and good electric conductivity, in addition to its flexibility and robustness, thereby becoming a very promising material to be used as a transparent electrode in the next-generation flexible displays and solar panels. In the radio-frequency (RF) region, the graphene transistor is a good candidate for power amplifiers and frequency multipliers, due to its high carrier mobility and its unique ambipolar transport characteristics. In this chapter, some of the most recent advances in graphene nanoelectromagnetics and its potential applications in various ranges of the spectrum are reviewed.