Dynamics of a self-phase-locked nondegenerate optical parametric oscillator with nonsymmetric feedback loops

We discuss the evolution of two-mode states of a self-phase-locked type-II nondegenerate optical parametric oscillator with homodyne-mediated quantum feedback. It is shown that different strengths of the feedback loops can simulate the effect of a squeezed thermal environment and lead additionally to the process of the parametric-down conversion for each mode. In the steady state regime all initial density matrices evolve towards a Gaussian equilibrium state. It is shown that the nonsymmetric feedback can further increase entanglement of the equilibrium state. Dynamical behaviour of intracavity entanglement for a number of initial states is investigated, and entanglement sudden death and birth phenomena, and a delay birth of entanglement are reported.