SIGNAL SWITCHING BY A CONTROL BEAM IN A NONLINEAR COUPLER

Power- and phase-controlled all-optical switching in a nonlinear fused-tapered coupler is presented. The induced switching is caused by a control beam applied to the coupler and is insensitive to the relative phase variation between the control and the signal. The switching behavior depends on the choice of the frequency of the control, its polarization, its strength, and the arm from which it is applied to the coupler. Depending on these initial conditions, the critical switching power ranges from being reduced as compared with the no-control case to being increased and even being nonexistent. The underlying physical concepts presented here can be generalized to include any two-mode-interference coupler device.