Kilowatt-level stimulated-Brillouin-scattering-threshold monolithic transform-limited 100 ns pulsed fiber laser at 1530 nm

We demonstrate a high-stimulated-Brillouin-scattering-threshold monolithic pulsed fiber laser in a master oscillator power amplifier configuration that can operate over the C band. In the power amplifier stage, we used a newly developed single-mode, polarization maintaining, and highly Er/Yb codoped phosphate fiber with a core diameter of 25 microm. A single-frequency actively Q-switched fiber laser was used to generate pulses in the hundreds of nanoseconds at 1530 nm. We have achieved peak power of 1.2 kW for 105 ns pulses at a repetition rate of 8 kHz, corresponding to a pulse energy of 0.126 mJ, with transform-limited linewidth and diffraction-limited beam quality.