Abstract
In the framework of Hamiltonian formalism the quantum statistical properties of an optical field propagating inside a directional coupler operating by nondegenerate parametric amplification are studied. We investigate the effect of switching between the input modes and the outgoing fields from the coupler. Particular attention is paid to two-mode squeezing, the 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 \1] and the other modes are in vacuum states, the coupler can serve as a generator of a coherent state. Furthermore, regimes for the generation and transmission of squeezed and/or sub-Poissonian light are found.