Ultra-compact optical modulator by graphene induced electro-refraction effect

We report a highly tunable graphene embedded waveguide which overall modal index is in linear relationship with the in-plane permittivity of graphene and the electro-refraction effect has been significantly enhanced after graphene is embedded. An eight-layer graphene embedded Mach-Zender modulator has been theoretically demonstrated with the advantage of ultra-compact footprint (4 x 30 mu m(2)), high modulation efficiency (20V.mu m), fast modulation speed, and large extinction ratio (35 dB). Our results may promote various on-chip active components, boosting the utilization of graphene in optical applications. (C) 2013 AIP Publishing LLC.