  This paper is concerned with two rather basic phenomena: the incoherent
fluorescence spectrum of an atom driven by an intense laser field and the
coupling of the atom to the (empty) modes of the radiation field. The sum of
the many-photon processes gives rise to the inelastic part of the atomic
fluorescence, which, for a two-level system, has a well-known characteristic
three-peak structure known as the Mollow spectrum. From a theoretical point of
view, the Mollow spectrum finds a natural interpretation in terms of
transitions among laser-dressed states which are the energy eigenstates of a
second-quantized two-level system strongly coupled to a driving laser field. As
recently shown, the quasi-energies of the laser-dressed states receive
radiative corrections which are nontrivially different from the results which
one would expect from an investigation of the coupling of the bare states to
the vacuum modes. In this article, we briefly review the basic elements
required for the analysis of the dynamic radiative corrections, and we
generalize the treatment of the radiative corrections to the incoherent part of
the steady-state fluorescence to a three-level system consisting of 1S, 3P and
2S states.
