An extraordinary electromagnetic wave of large amplitude will produce a quasilinear dc drift of electrons relative to ions, which can be modulated for feedback stabilization of low‐frequency waves. The effect occurs at the upper hybrid resonance. A promising way to penetrate the cut‐off in a fusion plasma is to use the nonlinear interaction of twoCO2laser beams to produce a difference frequency near &ohgr;h. We have extended the cold plasma analysis for this process and find that the intensities required are not unreasonable even when thermal effects are taken into account.