Sub-nanosecond all-normal-dispersion mode-locked Yb-doped fiber oscillator and its amplifier

We report two different pulse widths sub-nanosecond mode-locked Yb-doped fiber laser oscillators and a high power all-fiber master oscillator power amplifier (MOPA). Firstly, a 24.2 m long-cavity all-fiber mode-locked nanosecond laser oscillator has been demonstrated. Stable nanosecond pulses are achieved through nonlinear polarization rotation mode-locking technique rather than conventional methods. The pulse width is 1.1 ns and the central wavelength is 1042 nm with 3-dB bandwidth of 9.8 nm. Meanwhile the laser oscillator’s maximum average output power is 79.4 mW with repetition rate of 8.5 MHz, corresponding to pulse energy of 9.3 nJ. Secondly, a sub-nanosecond mode-locked Yb-doped fiber laser oscillator is achieved only by changing the laser cavity to 7.8 m. It produces 104.3 mW maximum average output power with 26.2 MHz repetition rate at 1042 nm. Pulse width is 0.55 ns with single pulse energy of 4.0 nJ. Finally, we adopt the second laser oscillator as a seed source of MOPA. 10.5 W average output po...