Electrical control of silicon photonic crystal cavity by graphene.

The efficient conversion of an electrical signal to an optical signal in nanophotonics enables solid state integration of electronics and photonics. The combination of graphene with photonic crystals is promising for electro-optic modulation. In this paper, we demonstrate that by electrostatic gating a single layer of graphene on top of a photonic crystal cavity, the cavity resonance can be changed significantly. A ~2 nm change in the cavity resonance line width and almost 400% (6 dB) change in resonance reflectivity is observed. In addition, our analysis shows that a graphene-photonic crystal device can potentially be useful for a high speed and low power absorptive and refractive modulator, while maintaining a small physical footprint.