  In this paper, we introduce a controllable method for producing two and
three-mode entangled coherent states (ECS's) using atom-field interaction in
cavity QED and beam splitter. The generated states play central roles in linear
optics, quantum computation and teleportation. We especially focus on qubit,
qutrit and qufit like ECS's and investigate their entanglement by concurrence
measure. Moreover, we illustrate decoherence properties of ECS's due to noisy
channels, using negativity measure. At the end the effect of noise on monogamy
inequality is discussed.
