Ultra-high repetition-rate (tens of MHz) nanosecond all-fiber amplifier based on a SESAM passively mode-locking fiber oscillator at 1064 nm

We report on a nanosecond all-fiber MOPA with ultra-high repetition rate (tens of MHz), which is seeded by a semiconductor saturable absorber mirror (SESAM) mode-locking fiber oscillator at 1064 nm. Ultra-high repetition rate of tens of MHz is realized by reducing fiber length in laser cavity. By using single-mode fiber stretcher with total length of 16 km, pulse width of mode locking laser pulse can be broadened from 28 ps to 1~7 ns. The maximum average power is achieved to be 54 W with pulse duration of 1.3 ns and repetition rate of 27.7 MHz. To the best of our knowledge, this is the first demonstration on an ultra-high repetition-rate (tens of MHz) nanosecond all-fiber MOPA based on a SESAM passively mode-locking fiber oscillator.