  In this letter we show that the dichroism and ellipticity induced on a linear
polarized light beam by the presence of a magnetic field in vacuum can be
explained in the framework of the de Broglie's fusion model of a photon. In
this model it is assumed that the usual photon is the spin 1 state of a
particle-antiparticle bound state of two spin 1/2 fermions. The other S=0 state
is referred to as the \emph{second} photon. On the other hand, since no charged
particle neither particles having an electric dipole are considered, no effect
is predicted in the presence of electric fields and this model is not in
contradiction with star cooling data or solar axion search.
