700-kW-Peak-Power Monolithic Nanosecond Pulsed Fiber Laser

We report a high-pulse energy, high-peak power, and monolithic nanosecond pulsed fiber laser source at ~1064 nm in master oscillator-power amplifier configuration. The seed source is a directly modulated laser diode, producing nanosecond pulses as short as ~3 ns with ~1-W peak power and a tunable repetition rate. Three core-pumped fiber amplifier stages and two double-cladding fiber amplifier stages were built to boost the peak power and the pulse energy of the ~3-ns seed pulses to ~697 kW and ~2.3 mJ, respectively. The all-fiber construction of the whole laser system enables compact size, maintenance-free, and robust operation.