Single polarization picosecond fiber MOPA power scaled to beyond 500 W

We demonstrate a gain-switched diode-seeded, ytterbium-doped fiber based master oscillator power amplifier (MOPA) system, capable of delivering 2.4 μJ, 35 ps pulses at a repetition frequency of 215 MHz in a single-polarization, close to diffraction limited beam. We are aware that the corresponding average power of > 500 W is a record for such a MOPA system. Further pulse energy scaling was limited primarily by the onset of nonlinear effects such as self-phase modulation and stimulated Raman scattering which led to a compromised pulse quality at higher peak powers (> 70 kW). (letter)