  The unconventional properties of graphene, with a massless Dirac band
dispersion and large coherence properties, have raised a large interest for
applications in nanoelectronics. In this work, we emphasize that graphene two
dimensional character combined with current standard lithography processes
allow to achieve devices smaller than the Dirac electrons wavelength. In this
regime, we demonstrate that the electronic properties present deep analogies
with subwavelength optics phenomena. We describe the rich transport physics in
graphene-based nanodevices through optical analogies: From the Bethe and
Kirchhoff-like diffraction patterns in the conductance of graphene slits to the
Fabry-Perot oscillations of the conductance in nanoribbons. We introduce the
concept of {\it electronic diffraction barriers}, which transmission cancels at
the Dirac point. This gives central insight in the properties of Graphene
subwavelength devices including nanoelectronics standard systems, such as
quantum dots. As an application we propose a new type of quantum dots, namely
functionalized subwavelength quantum dots, which could be used as molecular
spin valves.
