  We have developed a device fabrication process to pattern graphene into
nanostructures of arbitrary shape and control their electronic properties using
local electrostatic gates. Electronic transport measurements have been used to
characterize locally gated bipolar graphene $p$-$n$-$p$ junctions. We observe a
series of fractional quantum Hall conductance plateaus at high magnetic fields
as the local charge density is varied in the $p$ and $n$ regions. These
fractional plateaus, originating from chiral edge states equilibration at the
$p$-$n$ interfaces, exhibit sensitivity to inter-edge backscattering which is
found to be strong for some of the plateuas and much weaker for other plateaus.
We use this effect to explore the role of backscattering and estimate disorder
strength in our graphene devices.
