Emission spectrum of a Λ-type three-level atom driven by a two-mode field

An analytical expression of emission spectrum for Λ-type three-level atom interacted with two-mode cavity field is given. The characters of the emission spectrum for the field in photon number state, coherent state and SU(2) coherent state are exhibited. The effects of the atomic initial state, the field property on the time-dependent physical spectrum are analyzed.