  We studied theoretically the excitonic energy levels and the optical
absorption spectra for double quantum wells, both symmetric and asymmetric, in
the presece of an homogeneous magnetic field. Within the effective mass
approach, we expanded the excitonic wave function, in an orthogonal basis
formed by products of electron and hole wave functions in the growth direction
z, and one particle solutions of the magnetic Hamiltonian in the x-y plane. We
applied our method to the case of Al_xGa_{1-x}As, for which we showed how the
exciton wave function vary, and how the basis functions are mixed in a non
trivial way by the effect of the Coulomb potential. By taking into account all
the mixing between the elements in our base, we get anti-crossing between
excited excitonic states not reported previously.
