  We proposed two linear optics based entanglement concentration protocols
(ECPs) to obtain maximally entangled 4-mode Cluster-type entangled coherent
state (ECS) from less (partially) entangled Cluster-type ECS. The first ECP is
designed using a superposition of single-mode coherent state with two unknown
parameters, whereas the second ECP is obtained using a superposition of
single-mode coherent state and a superposition of two-mode coherent state with
four unknown parameters. The success probabilities have been calculated for
both the ECPs. Necessary quantum circuits enabling future experimental
realizations of the proposed ECPs are provided using linear optical elements.
Further, the benefit of the proposed schemes is established in the context of
long distance quantum communication where photon loss is an obstruction.
