VECTOR SOLITONS AND THEIR INTERNAL OSCILLATIONS IN BIREFRINGENT NONLINEAR-OPTICAL FIBERS

In this article, the vector solitons in birefringent nonlinear optical fibers are studied first, Special attention is given to the single-hu mp vector solitons due to evidences that only they are stable, Questio ns such as the existence, uniqueness, and total number of these solito ns are addressed, It is found that the total number of them is continu ously infinite and their polarizations can be arbitrary, Next, the int ernal oscillations of these vector solitons are investigated by the li nearization method, Discrete eigenmodes of the linearized equations ar e identified, Such modes cause to the vector solitons a kind of perman ent internal oscillations, which visually appear to be a combination o f translational and width oscillations in the A and B pulses, The nume rically observed radiation shelf at the tails of interacting pulses is also explained, Finally, the asymptotic states of the perturbed vecto r solitons are studied within both the linear and nonlinear theory, It is found that the state of internal oscillations of a vector soliton is always unstable, It invariably emits energy radiation and eventuall y evolves into a single-hump vector soliton state.