  In this communication we introduce a new model which represents the
interaction between an atom and two fields injected simultaneously within a
cavity including the nonlinear couplers. By using the canonical transformation
the model can be regarded as a generalization of several well-known models. We
calculate and discuss entanglement between the tripartite system of one atom
and the two cavity modes. For a short interaction time, similarities between
the behavior based on our solution compared with the other simulation based on
a numerical linear algebra solution of the original Hamiltonian with truncated
Fock bases for each mode, is shown. For a specific value of the Kerr-like
medium defined in this letter, we find that the entanglement, as measured by
concurrence, may terminate abruptly in a finite time.
