Nonlinear switching recovery in planar directional coupler with loss

Twin-core nonlinear directional couplers that include loss and nonlinear refractive index are examined. The inclusion of loss results in the increase of the critical power of the coupler while the switching characteristics deteriorate. To compensate for this behavior associated with the loss, we investigate the effect of the nonlinearity profile on the performance of an increasing nonlinearity coupler. We have shown that appropriate shaping of the nonlinear self-phase modulation profile is quite effective in recovering, almost completely, the original switching behavior associated with the lossless situation. It is concluded that the exponential nonlinearity profile is nearly optimum for the recovery of the lossless switching behavior.