Search for stimulated photon-photon scattering in vacuum

We have searched for stimulated photon scattering in vacuum at a center of mass photon energy of 0.8 eV. The QED contribution to this process is equivalent to four wave mixing in vacuum. No evidence for gamma gamma scattering was observed. The corresponding upper limit of the cross-section is sigma(Lim) = 1.5 x 10(-48) cm(2).