Soliton switching in twin-core fibers with gain and loss

Soliton propagation and switching in twin-core nonlinear fibers with gain and loss have been investigated based on a pair of coupled nonlinear Schr?dinger equations. We have found the fiber with equal amount of gain in both cores has the minimum ascending energy Δɛ of 1.5K, while the fiber with a certain amount of gain in one core and the same amount of loss in the other core has the minimum switching thresholdɛ _th of 2.05K. A new vector field is defined and its potential function is derived, which explains the switching behavior of the minimumɛ _th switch satisfactorily.