  In a previous paper, we have already considered the system composed by a two
level atom interacting with a coherent external electromagnetic field. No
application whatsoever has been made of the rotating wave approximation. Being
specially interested in the problem of higher harmonic generations for the case
of very intense laser fields, we have developed in this letter a much more
efficient way to obtain these solutions as well as to carry out some
calculations in a range in which the parameters take extreme values. Also the
formalism allows us now to provide analytic expressions in the WKB regime for
the electric dipole moment and the population inversion. The spectrum can be
decomposed in periodic and non-periodic contributions. Only the latter depends
upon the Floquet exponent and can be responsible of the main complexities of
the observed Rabi revivals and the hyper-Raman shift.
