Superposition de deux ondes d'indices d'heterogeneite differents

Heterogeneous plane and uniform electromagnetic waves are particular solutions of Maxwell's equations. The sum of two of these solutions of the same frequency is generally not a wave of the same kind. A new type of interference appears for two heterogeneous plane and uniform components of different heterogeneity. The experimental proof of this phenomenon would show the dependence of the phase velocity on the heterogeneity. In the general case, the equal-amplitude surfaces of the various fields components are different; the same holds for the equal-phase surfaces. It is not always possible to define an eikonal and a wave surface for such a solution of Maxwell's equations. These difficulties disappear for waves of equal or opposite heterogeneity index.