  Upcoming Weak Lensing (WL) surveys can be used to constrain Dark Energy (DE)
properties, namely if tomographic techniques are used to improve their
sensitivity. In this work, we use a Fisher matrix technique to compare the
power of CMB anisotropy and polarization data with tomographic WL data, in
constraining DE parameters. Adding WL data to available CMB data improves the
detection of all cosmological parameters, but the impact is really strong when
DE--DM coupling is considered, as WL tomography can then succeed to reduce the
errors on some parameters by factors >10.
