  Graphene-based photodetectors, taking advantage of high carrier mobility and
broadband absorption in graphene, have recently experienced rapid development.
However, their performances with respect to the responsivity and bandwidth are
still limited by either weak light-graphene interaction or large
resistance-capacitance product. Here, we demonstrate a waveguide coupled
integrated graphene plasmonic photodetector on the silicon-on-insulator
platform. Benefiting from plasmonic enhanced graphene-light interactions and
subwavelength confinement of the optical energy, we present a small-footprint
graphene-plasmonic photodetector with bandwidth beyond 110GHz and intrinsic
responsivity of 360mA/W. Attributed to the unique electronic bandstructure of
graphene and its ultra-broadband absorption, the operational wavelength range
extending beyond mid-infrared, and possibly further, can be anticipated. Our
results show that the combination of graphene with plasmonic devices has great
potential to realize ultra-compact and high-speed optoelectronic devices for
graphene-based optical interconnects.
