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.
