An exact solution of the Fokker-Planck equation for a cascade micromaser

We have developed the quantum theory of a three-level two-photon cascade micromaser by considering the atoms initially prepared in a partial coherent superposition of upper and lower states and then injected into the cavity. The master equation for the maser field is derived and converted into a Fokker-Planck equation. An exact steady state solution of the Fokker-Planck equation is presented. It has been seen that the symmetry of the field in the cavity is not ``broken'' in contradiction to the one-photon case.