In this paper we show that the codirectional Kerr nonlinear coupler can generate Schrodinger-cat states, in
particular, Yurke-Stoler states based on the values of the interaction parameters. We show this analytically
through s-parameterized single-mode quasiprobability distribution functions. We confirm this fact also in the
evolution of the phase distribution.
In the framework of Hamiltonian formalism nonclassical effects of an optical field propagating inside a directional coupler containing nondegenerate parametric amplification have been studied. We investigate the effect of switching between the input modes and the out going fields from the coupler. Particular attention has been paid to two mode squeezing, second-order correlation function, quasiprobability distribution functions, and photon-number distribution. Incident number and coherent states are considered. It has been shown that when one of the modes enters the coupler in the Fock state and the other modes are in vacuum states, the coupler can serve as a generator for coherent state. Furthermore, regimes for generation and transmission of squeezed and/or sub-Poissonian light are found.