Quantum statistics and dynamics of nonlinear couplers with nonlinear exchange

In this paper we derive the quantum statistical and dynamical properties of nonlinear optical couplers composed of two nonlinear waveguides operating by second subharmonic generation, which are coupled linearly through evanes cent waves and nonlinearly through non-degenerate optical parametric intera ction. Main attention is paid to generation and transmission of non-classic al light, based on a discussion of the squeezing phenomenon, the normalized second-order correlation function and quasiprobability distribution functi ons. Initially coherent, number and thermal states of optical beams are con sidered. In particular, results are discussed with dependence on the streng th of the nonlinear coupling relatively to the linear coupling. We show tha t if the Fock state /1] enters the first waveguide and the vacuume state /0 ] enters the second waveguide, the coupler can serve as a generator of sque ezed vacuum state governed by the coupler parameters. Further, if thermal f ields enter initially the waveguides the coupler plays a similar role as a microwave Josephson-junction parametric amplifier to generate squeezed ther mal light.