  Mode division multiplexing has been mooted as a future technology to address
the impending data crunch of existing fiber networks. Present demonstrations
delineate the light source from the mode creation steps, potentially inhibiting
integrated solutions. Here we demonstrate an integrated mode generating source
in the form of a digitally controlled solid state laser with an intra-cavity
spatial light modulator. In our proof-of-principle experiment we create fiber
modes on demand and couple them directly into a few-mode fiber, where after
transmission they are decoupled by modal decomposition. This is the first
demonstration of a single source for encoding information into the spatial
modes of light.
