Abstract
Acceptable forms of nonlinearities of both the field and the intensity-dependent atom-field coupling in a generalized Jaynes–Cummings model are considered. The time-dependence of the atom-field system is obtained, by means of which we produce the analytical forms of the fluorescence and absorption spectra produced by an atom in an ideal cavity using the dressed states of the system. We investigate the influences of the mean number of photons, detuning, the nonlinearities and Stark shifts on the spectra, for initial coherent and thermal states. It is shown that features of the fluorescence and absorption spectra are influenced significantly by the kinds of the nonlinearities and the detuning.