Harmonic Mode-Locking From Erbium-Doped Fiber Self-Starting Mamyshev Oscillator

Mamyshev oscillators produce high-performance pulses, rely on its ultrahigh modulation depth. Just as the two sides of the coin, it also restricts the pulse self-starting and frequency increase. Here we present a Mamyshev oscillator with a key design feature that enable self-starting operation and high-order harmonic mode-locking from an all-fiber laser, based on two filters with fixed bandwidths. The laser generates 89th order that corresponding to the repetition rate of 395.2 MHz. The signal-to-noise ratio of each harmonic number exceeds 60 dB. This result perfectly balances the contradiction between the high modulation depth and the self-starting harmonic mode-locking in the Mamyshev oscillator, making it an attractive tool for practical applications in high repetition rateregion.