Pulse patterns induced by narrowband filters in self-starting erbium-doped Mamyshev oscillators

Mamyshev oscillators (MO) can be equivalently regarded as passively mode-locked fiber lasers, but this equivalence is achieved solely through spectral broadening and filtering. Therefore, the formation mechanism of its pulse patterns is different from that of other passively mode-locked fiber lasers. In this study, an MO with narrowband filters was constructed. By comparing the differences between the oscillator output spectrum and the amplified spontaneous emission spectrum, the key spectral conditions for MO self-starting were clarified. The self-start law was revealed at the experimental level, and stable single soliton output was achieved simultaneously. Further exploration reveals that the formation of pulse patterns such as soliton clusters, bound state soliton clusters, and harmonic mode locking in MO is not dominated by the previous study's believed peak-power-clamping effect in the cavity, but rather the result of the synergistic effect of narrowband filtering and self-phase modulation effects. This effect transforms MO from a single soliton operating state to a multi-soliton pulse patterns operating state. This discovery breaks through the previous explanations based on the peak-power-clamping effect, providing what we believe to be a new mechanism for the formation of MO pulse patterns, offering strong support for the construction of a complete MO theoretical system and the advancement of fundamental research in this field.