  Coherent feedback control (CFC) of multipartite optical entangled states
produced by a non-degenerate optical parametric amplifier is theoretically
studied. The features of the quantum correlations of amplitude and phase
quadratures among more than two entangled optical modes can be controlled by
tuning the transmissivity of the optical beam splitter in CFC loop. The
physical conditions to enhance continuous variable multipartite entanglement of
optical fields utilizing CFC loop are obtained. The numeric calculations based
on feasible physical parameters of realistic systems provide direct references
for the design of experimental devices.
