Nonclassical light in symmetric nonlinear directional coupler

We examine the quantum-statistical properties of light beams in a directional symmetric nonlinear coupler composed of one linear waveguide and two nonlinear waveguides operating by the second-harmonic generation. Linear and nonlinear mismatches are taken into account. Non-classical behaviour of single and compound modes in such a device is investigated. This work was partially supported by the Grant 202/96/0421 of the Czech Grant Agency and by the Complex Grant VS96028 of Czech Ministry of Education.