Spectral properties of a micromaser: Atomic-beam statistics and the field correlation function

In lasers with strong atom-field coupling, Rabi-type oscillation effects are apparent not only in the atomic inversion and the photon number, but also in the field correlation function. Whereas the former play an important role in the standard micromaser with Poissonian injection, the latter are particularly relevant in lasers with non-Poissonian atomic injection. In such lasers, there is generally no steady state in the usual sense, and the field correlation function is really a two-point correlation. We analyze the field correlation function and the spectrum under these circumstances. Our analysis uses a stochastic simulation as well as an approximate analytical description. For lasers with a regular injection, this analysis explains the occurrence of a multipeak spectrum in simple terms. In the more general situation, the spectrum is related to the counting statistics of the atoms. Conditions for an experimental realization are discussed.