Nonlinear optical properties of the magnetized QED Vacuum

New processes associated with the nonlinear optical properties of the electromagnetic vacuum, as predicted by quantum electrodynamics are described. We consider the presence of a static and a rotating magnetic field. The cases of harmonic generation and two different types of sideband cascades are considered. First order and second order effects with respect to the external magnetic field are discussed in detail. Possible experimental configurations using ultra-intense lasers are compared with the alternative use of cw lasers in stable optical cavities.