Light propagation in non-linear electrodynamics

Working on the approximation of low frequency, we present the light cone co nditions for a class of theories constructed with the two gauge invariants of the Maxwell field without making use of average over polarization states . Different polarization states are thus identified describing birefringenc e phenomena. We make an application of the formalism to the case of Euler-H eisenberg effective Lagrangian and well know results are obtained. (C) 2000 Elsevier Science B.V. All rights reserved.