  Free-space optical communication with spatial modes of light has become
topical due to the possibility of dramatically increasing communication
bandwidth via Mode Division Multiplexing (MDM). While both scalar and vector
vortex modes have been used as transmission bases, it has been suggested that
the latter is more robust in turbulence. Using orbital angular momentum as an
example, we demonstrate theoretically and experimentally that the crosstalk due
to turbulence is the same in the scalar and vector basis sets of such modes.
This work brings new insights about the behaviour of vector and scalar modes in
turbulence, but more importantly it demonstrates that when considering optimal
modes for MDM, the choice should not necessarily be based on their vectorial
nature.
