  Self-organization of temporal modes in mode-locked lasers usually starts from
quantum noise. In this process, incoherent spontaneous emission is steered into
coherent ultrashort pulses by dissipation and nonlinearity. In this work, we
investigated self-organization dynamics in a mode-locked Mamyshev oscillator
starting from coherent pulse seeds as opposed to quantum noise. We observed
that the coherence of the seed can be remembered or forgotten depending on the
initial inverse population. The excessive nonlinearity in the coherence amnesia
regime can devastate the seed coherence, causing the oscillator to undergo a
chaotic transition lasting hundreds of round trips before regaining coherence.
Conversely, the oscillator converges in only a few round trips for the
coherence memory regime. A heterodyne technique was developed to record the
fast varying optical phase and characterize these two regimes. Dissipative
soliton molecules were synthesized from external pulse pair seeds via the
coherence memory pathway. In this case, a plateau of the generated pulse
spacing independent from seed pulse spacing, i.e., amnesia of the seed spacing,
was observed for close spaced seed pulse pairs. Moreover, we show that pulse
seeds can be used for laser reconfiguration and pulse pattern control. Our work
paves a way to control transient pulse dynamics and steady pulse forms on
demand in mode-locked lasers.
