All-optical routing switch using a fiber nonlinear directional coupler and controlling solitons

A routing all-optical switch in which the signal, consisting of a fundamental soliton, is directed into either of the output ports of a 2/spl times/2 nonlinear directional coupler is investigated by means of computer simulation. The routing is controlled by copropagating a controlling pulse along with the signal pulse. Four different schemes for doing this are explored where the polarization of the controlling pulse with respect to the signal soliton may be varied, or the controlling pulse may be launched into either of the input ports, or it may have a wavelength different from that of the signal. It is shown that only one of the schemes allows a high switching efficiency and enables distortionless propagation of the signal pulse through the coupler.