Bound States of Vector Dissipative Solitons

We report on the first experimental observation of bound states of vector dissipative solitons (VDSs) in an erbium-doped fiber laser mode locked with a semiconductor saturable absorber mirror and operated in the normal dispersion regime. Bound states of either the coherently coupled VDSs or the incoherently coupled VDSs were obtained. No polarization evolution was observed for either of the bound VDSs. Both types of bound VDSs have a fixed soliton separation, which is invariant to the laser operation condition. Numerical simulations confirm the experimental observations.