Graphene photodetectors for high-speed optical communications

Although silicon has dominated solid-state electronics for more than four decades, a variety of other materials are used in photonic devices to expand the wavelength range of operation and improve performance. For example, gallium-nitride based materials enable light emission at blue and ultraviolet wavelengths, and high index contrast silicon-on-insulator facilitates ultradense photonic devices. Here, we report the first use of a photodetector based on graphene, a two-dimensional carbon material, in a 10Gbit s-1 optical data link. In this interdigitated metal-graphene-metal photodetector, an asymmetric metallization scheme is adopted to break the mirror symmetry of the internal electric-field profile in conventional graphene field-effect transistor channels, allowing for efficient photodetection. A maximum external photoresponsivity of 6.1mAW-1 is achieved at a wavelength of 1.55νm. Owing to the unique band structure of graphene and extensive developments in graphene electronics and wafer-scale synthesis, graphene-based integrated electronic-photonic circuits with an operational wavelength range spanning 300nm to 6νm (and possibly beyond) can be expected in the future. © 2010 Macmillan Publishers Limited. All rights reserved.