Propagation dynamics of ultrashort pulses in nonlinear fiber couplers.

The nonlinear fiber coupler is considered as a Hamiltonian dynamical system with an infinite number of degrees of freedom, with the soliton states of the coupler being the singular points of this dynamical system. Numerical simulations show that arbitrary initial conditions give rise, asymptotically, to oscillations around some of the stable singular points and some amount of radiation. Examples of different initial conditions, including unstable soliton states and single pulses launched in one channel of the coupler are considered.