Numerical study of soliton switching in active three-core nonlinear fiber couplers

A numerical investigation, based on the use of a finite-element-based beam propagation algorithm, of all-optical switching of solitons in three-core nonlinear fiber couplers in the presence of gain is presented. The numerical algorithm is described in detail. Linear gain is found to lead to sharper transmittance characteristics, a considerable lowering of the switching powers, and also to an increase in the power exchange between the input and center core for a nearest-neighbor core arrangement. As in the case of a two-core nonlinear fiber coupler, the finite gain bandwidth is found to lead to the deterioration of the switching characteristics.