Dark soliton switching in nonlinear fiber couplers with gain

• Dark soliton switching is numerically presented by adding linear gains.
• Increasing the gain of bar channel improves switching characteristics.
• Increasing the gain of cross channel decreases switching characteristics.
• Threshold power increases whilst increasing normalized coupling coefficient.
• Second-order coupling coefficient dispersion does not affect the switching.

In this paper, we present a study of numerical simulations for all-optical dark soliton switching in nonlinear directional couplers with gain additions in two waveguides whilst considering intermodal dispersion and its higher-order effects. The effects of possible combinations of gain addition in the bar channel as well as in the cross channel of the nonlinear couplers are theoretically presented. In addition, the consequence of second-order coupling coefficient dispersion based on coupled mode theory for dark soliton switching is numerically depicted.