Non-classical behaviour and switching in Kerr nonlinear couplers

Directional nonlinear couplers composed of two Kerr nonlinear waveguides ar e studied. Quantum consistent solutions of the equations of motion are obta ined showing the collapses and revivals of the field mode amplitudes. The a pproximate method is also adopted for the contradirectional geometry and th e switching accompanied by collapses of the modes is revealed. Kerr coupler s with varying linear coefficients are examined and possible controls of th e switching of modes, for instance, digital switching and fast switching ar e demonstrated. The two-mode squeezing of vacuum fluctuations and the gener ation of pure states are shown.