Investigation of pulse splitting behaviour in a dissipative soliton fibre laser

Pulse splitting in a dissipative soliton fibre laser taking the nonlinear polarization evolution (NPE) rejection port as the output is investigated. Both numerical and experimental results show that with enhancement of the NPE effect, the pulse and its spectrum from the rejection port will split into two parts, which are the wings of the intra-cavity circulating pulse. It is consistent with what we expect from nonlinear polarization rotation acting on the pulse. However, to the best of our knowledge, this is the first systematic report on this phenomenon. Numerical simulation results show that when the output pulse splits into two sub-pulses, the evolution of the intra-cavity pulse is totally different from the case in which the rejected pulse has a high-quality intensity profile.