Approaching the Intrinsic Lifetime and Modulating a Graphene Plasmonic Resonance at a Few Hundred GHz

Graphene-based metamaterials exhibit large tunability, low insertion loss, and high field confinement compared with metal-based structures. Graphene-based metamaterials may find numerous applications in optical modulators, optoelectronic devices, and chemical sensors in the few-hundred-GHz and low-THz regime, constituting a new frontier as electronics and wireless communication continuously push further to higher frequencies. However, the main challenge is overcoming loss in graphene-based resonant applications. Here, a low-loss graphene plasmonic resonant modulator is demonstrated that operates at a few hundred GHz and 1 THz. The modulation depth is in excess of 35% with two layers of graphene. Numerical simulations show good agreement with the experimental results and reveal 100-200 fs lifetimes, which are approaching the intrinsic lifetime of the graphene plasmon due to the suppression of loss from phonon and edge scattering. The above values are the closest to electronic frequencies and represent the longest plasmon lifetime and largest modulation depth in graphene plasmon resonance devices reported so far.