Ultrafast all-optical plasmonic graphene modulator.

By utilizing the ultrafast dynamics of the photo-excited electrons in graphene, we theoretically present an ultrafast all-optical plasmonic modulator. With the help of an external pump, the femtosecond thermodynamics of the hot carriers can tune the Fermi level of the graphene sheet in less than 1 ps, which is the dependence of the support for the surface plasmonic wave. This device shows the ability to operate from the near-infrared regime to the far-infrared spectrum with the extinction ratio over 10 dB and the pump fluence of 0.41  mJ/cm2. Such an ultrafast modulator may pave the way for designing the ultrahigh speed integrated photonics circuits.