Towards Low-power Near-infrared Modulators operating at Telecom Wavelengths: when Graphene Plasmons Frustrate their Metallic counterparts

A free-space electro-optic modulator device exploiting graphene’s surface plasmon polariton (SPP) at near-infrared frequencies is proposed and theoretically studied. The device is made up of two resonant structures, the first being a metallic SPP displaying broadband absorption, and the second graphene’s own SPP, which is shown to frustrate the metallic plasmon when excited, leading to a narrow reflectance peak. Doping of the graphene to achieve Fermi-level tuning is shown to shift the wavelength of the frustration phenomenon, thereby enabling the use of the device as a modulator. A reduction of 20% in the switching energy is expected due to the unique principle of operation which, crucially and contrary to most work in this field, does not rely on electroabsorption but electrorefraction changes in graphene. This coupled SPP resonator geometry also permits efficient channeling of optical energy from free space into graphene’s SPP at near-infrared frequencies.