Transitional and steady mode-locking evolution of dissipative solitons

We have experimentally observed the transitional and steady mode-locking (ML) evolution of dissipative solitons (DSs). It is found that pulses with different energies can coexist in the cavity during the evolution. When an additional pulse is generated from the laser, it initially exhibits weak intensity, and then gradually develops into the fully grown pulse with the increase of pump power. Meanwhile, the spectral profile of pulses is modulated at its top. The dynamic processes occur stage by stage, and can be regarded as the transitional states between the two nearby steady ML states. To our best knowledge, this is the first report on experimental observations for the detailed dynamic evolutions of pulse shaping in a DS laser.