Soliton interactions for a generalized variable-coefficient coupled higher-order nonlinear Schrodinger system in an inhomogeneous optical fiber

Studied in this paper are the interactions between bright-dark solitons for a generalized variable-coefficient coupled higher-order nonlinear Schrodinger system, which can be used to describe the simultaneous propagation of two ultrashort pulses in an inhomogeneous optical fiber. Under certain constraints, we obtain the analytic bright-dark one-and two-soliton solutions through the Hirota method and symbolic computation. With the help of this analytic treatment, properties of the single solitons, including the amplitudes, velocities, widths and central positions, are studied. Considering the amplification/absorption, group velocity and third-order dispersion effects, we study the interactions between two solitons with periodical variations of amplitudes and velocities. We find that the amplitudes of the two solitons depend solely on the amplification/absorption coefficient, while the velocities of the two solitons are related to the group velocity and third-order dispersion coefficients. Switches from the periodical interactions to head-on interactions and parallel propagation are presented.