Broadband silicon optical modulator using a graphene-integrated hybrid plasmonic waveguide

Abstract

Graphene is an excellent electronic and photonic material for developing electronic–photonic integrated circuits in Si-based semiconductor devices with ultra wide operational bandwidth. As an extended application, here we propose a broadband silicon optical modulator using a graphene-integrated hybrid plasmonic waveguide, and investigate the optical characteristics numerically at a wavelength of 1.55 μm. The optical device is based on the surface plasmon polariton absorption of graphene. By electrically tuning the graphene’s refractive index as low as that of a noble metal, the hybrid plasmonic waveguide supports a strongly confined highly lossy hybrid long-range surface plasmon polariton strip mode, and hence light coupled from an input waveguide experiences significant power attenuation as it propagates along the waveguide. Over the entire C-band from 1.530 to 1.565 μm wavelengths, the on/off extinction ratio is larger than 13.7 dB. This modulator has the potential to play a key role in realizing graphene–Si waveguide-based integrated photonic devices.