On-chip graphene optoelectronic devices for optical interconnects

Graphene is emerging as an attractive active material for on-chip opto-electronic devices. We describe recent progress on hybrid graphene-silicon photonic devices for optical interconnects in the telecom wavelength region. By coupling graphene to an optical cavity, we demonstrated an efficient electro-optic modulator that features a modulation depth of 10 dB and a switching energy of 300 fJ. In addition, we describe a novel silicon waveguide-integrated photodetector based on a 53-μm-long graphene layer that couples to the evanescent field of the waveguide mode, resulting in more than 60% absorption of the input light. We demonstrated a responsivity in excess of 0.1 A/W, a data transmission of 12 Gbps, bandwidth in excess of 20 GHz. These results show the feasibility of graphene as the active material in silicon photonic integrated circuits.