Phase-and polarization-insensitive all-optical switching by self-guiding in quadratic media

We demonstrate numerically that a frequency-degenerate process through type II downconversion in a quadratic nonlinear waveguide leads to the formation of spatial simultons and all-optical switching in the presence of a control signal. This novel effect is phase independent, generally insensitive to polarization, and weakly affected by the magnitude of the control input. Multiple solitary waves can also be obtained, depending on the details of the interaction. (C) 1997 Optical Society of America.