RESONANT SPLITTING OF A VECTOR SOLITON IN A PERIODICALLY INHOMOGENEOUS BIREFRINGENT OPTICAL-FIBER

We analyze the dynamics of a two-component (vector) soliton in a model of a birefringent nonlinear optical fiber with a periodic spatial mod ulation of the birefringence parameter (group velocity difference). Ev olution equations for the parameters of the vector soliton are derived by means of a variational technique. Numerical simulations of these e quations demonstrate that the critical modulation amplitude necessary for splitting, regarded as a function of the soliton's energy, has a d eep minimum very close to the point at which direct resonance takes pl ace between the periodic modulation and an internal eigenmode of the v ector soliton in the form of small relative oscillations of the center s of the two components. A shallower minimum, which can be related to another internal eigenmode of the vector soliton, is also found. We fu rther briefly consider the internal vibrations of the vector soliton d riven by a constant force, which corresponds to the birefringence grow ing linearly with propagation distance. The effect predicted has pract ical relevance to ultrashort (femtosecond) optical solitons, and it ca n be employed in the design of fiber-optical logic elements.