  Herein we discuss the fabrication of ballistic suspended graphene
nanostructures supplemented with local gating. Using in-situ current annealing,
we show that exceptional high mobilities can be obtained in these devices. A
detailed description is given of the fabrication of bottom and different
top-gate structures, which enable the realization of complex graphene
structures. We have studied the basic building block, the p-n junction in
detail, where a striking oscillating pattern was observed, which can be traced
back to Fabry-Perot oscillations that are localized in the electronic cavities
formed by the local gates. Finally we show some examples how the method can be
extended to incorporate multi-terminal junctions or shaped graphene. The
structures discussed here enable the access to electron-optics experiments in
ballistic graphene.
