Polarization-Insensitive Optical Modulator Based on Single-Layer Graphene Sheets

We report the design of a highly efficient, compact and ultra-broadband hybrid graphene-silicon modulator. The design comprises a single graphene layer deposited on a silicon waveguide, using a thin hafnium dioxide dielectric spacer. The light-graphene interaction was tuned, by parametric optimization, in order to provide polarization-insensitive modulation. The simulation results indicate polarization-insensitive modulation in amplitude and phase, with a speed of 11.63 GHz, within the entire optical communications range. The energy per bit (
$E_{\text {bit}}$
) was also calculated for both modulation mechanisms, indicating a way to optimize the energy consumption according to the desired application. Significantly, we demonstrated efficient modulation with an energy consumption lower than 1 pJ/bit for both amplitude and phase modulation mechanisms. We expect that the fabrication of the proposed device helps to pave the way for ultra-broadband optical interconnects that can cope with the growing demand for higher capacity and bandwidth in optical communications.