High power burst-mode operated sub-nanosecond fiber laser based on 20/125μm highly doped Yb fiber

A master oscillator power amplification (MOPA) structured high power sub-nanosecond fiber laser with pulse bunch output is experimentally demonstrated. The seed was a figure-of-eight structured mode-locked fiber laser with a pulse duration of 700 ps and a repetition rate of 2.67 MHz. The seed pulse via two cascaded fiber couplers was multiplied to a pulse bunch, which was composed of 6 sub-pulses. The multiplied pulses were pre-amplified to an average power of 1.5 W through a cladding-pumping fiber amplifier. The pre-amplified laser was further amplified using a 20/125 μm large mode area (LMA) Yb-doped fiber. The laser emitted from the power-amplifier had an average power of 36 W, and a slope efficiency of 72%.