High-energy diode-seeded nanosecond 2  μm fiber MOPA systems incorporating active pulse shaping

We report on high-energy nanosecond-pulsed fiber master oscillator power amplifier (MOPA) systems seeded by semiconductor laser diodes at 2 μm incorporating arbitrary pulse-shaping capabilities. Two MOPA systems, one based on direct diode modulation and the second using additional electro-optic modulator (EOM) based shaping, are investigated, with up to 0.5 mJ (25 kHz) and 1.0 mJ (12.5 kHz) pulse energies achieved, respectively, for 100 ns pulses with user-defined pulse shapes. Our results indicate that further energy scaling with shaped output pulses is primarily limited by the maximum pulse peak power available from the seed laser diode and the dynamic range offered by the first generation of EOMs at 2 μm.