  We present a simple device architecture that allows all-electrical detection
of plasmons in a graphene waveguide. The key principle of our electrical
plasmon detection scheme is the non-linear nature of the hydrodynamic equations
of motion that describe transport in graphene at room temperature and in a wide
range of carrier densities. These non-linearities yield a dc voltage in
response to the oscillating field of a propagating plasmon. For illustrative
purposes, we calculate the dc voltage arising from the propagation of the
lowest-energy modes in a fully analytical fashion. Our device architecture for
all-electrical plasmon detection paves the way for the integration of graphene
plasmonic waveguides in electronic circuits.
