  Optical interconnects are becoming attractive alternatives to electrical
wiring in intra- and inter-chip communication links. Particularly, the
integration with silicon complementary metal-oxide-semiconductor (CMOS)
technology has received considerable interest due to the ability of
cost-effective integration of electronics and optics on a single chip. While
silicon enables the realization of optical waveguides and passive components,
the integration of another, optically absorbing, material is required for
photodetection. Germanium or compound semiconductors are traditionally used for
this purpose; their integration with silicon technology, however, faces major
challenges. Recently, graphene has emerged as a viable alternative for
optoelectronic applications, including photodetection. Here, we demonstrate an
ultra-wideband CMOS-compatible photodetector based on graphene. We achieve
multi-gigahertz operation over all fiber-optic telecommunication bands, beyond
the wavelength range of strained germanium photodetectors, whose responsivity
is limited by their bandgap. Our work complements the recent demonstration of a
CMOS-integrated graphene electro-optical modulator, paving the way for
carbon-based optical interconnects.
