High signal-to-noise ratio harmonic mode-locking Mamyshev oscillator at 1550nm

Harmonic mode-locking is the effective method to improve ultrafast pulse repetition rate for the current research. However, this way of increasing the repetition rate based on pulse splitting has inherent instability characteristics, manifested as low signal-to-noise ratio and loss of mode-locking. In this paper, Mamyshev regenerative oscillation mode-locking technique is used to effectively improve the signal to noise ratio of pulses by compressing the nonlinear chirp in the cavity under the condition of near-zero dispersion. In the experiment, we successfully achieved a harmonic mode-locked pulse of up to 16 orders, corresponding to a repetition rate of 78.56 MHz, and the signal-to-noise ratio of the highest harmonic order reached 70 dB. Our research not only solves the inherent defect of low repetition rate of Mamyshev oscillator, but also effectively improves the signal-to-noise ratio of harmonic mode-locked pulse. This mode-locked structure based on Mamyshev oscillator provides reference and operability for improving the stability of ultrafast fiber lasers.