Wideband Graphene Electro-Optic Modulator on 1D Photonic Crystal Cavity

Since the isolation of graphene monolayers in 2004, attention has turned to embedding this 2D material into optical components such as modulators, frequency converters and optical clocks. Indeed, graphene exhibits some remarkable optical properties such as wideband optical absorption in both normal-incidence (free-space applications) and grazing-incidence (waveguide based applications), intrinsic supporting of surface plasmon polariton (SPP) waves, and a full catalogue of non-linear optical behaviors including saturable absorption and multiple-photon mixing phenomena. These optical properties can be activated and deactivated for a given free space wavelength by "doping" graphene using the same gating techniques developed for solid state electronics; for example, in the case of absorption modulation, one must shift the Fermi level such that its separation from the Dirac point in energy (called the chemical potential) is equal to at least half the photon energy in order to render graphene transparent. Nonetheless, as an atomically thin monolayer, graphene's limited interaction with light in free space restricts its absorption to 2.3% across a wide spectral range for undoped samples.