Controllable discrete diffraction in cascade-induced waveguides

A new method for generating periodic lattices in quadratically nonlinear media by the three-wave cascade interaction is proposed. This method allows one to obtain stable structures with changeable parameters. These structures make it possible to realise the all-optical control of the character of the laser beam propagation. The use of the discrete diffraction allows the signal multiplexing in optical processing and information transfer devices and the control of the number of channels at the crystal output. The effect of the discrete diffraction anisotropy in the system of induced waveguides makes it possible to redistribute in the specified way the energy in the channels at the output. It is shown that the optical switching efficiency is maximal in the regime of the transverse Bragg resonance. The signal switching rate in optical lattices induced in a quadratically nonlinear medium is limited by the time of light propagation though the crystal and can achieve several terahertz.