Low repetition rate broadband high energy and peak power nanosecond pulsed Yb-doped fiber amplifier

We demonstrate a broadband fiber amplifier system emitting 10 nm pulses with 33 mJ pulse energy at repetition rates between 1 and 20 Hz. In combination with a pulse width of 10 ns, a corresponding peak output power over than 3 MW was achieved. This record performance was enabled by fiber with core diameter of 200 μm. Furthermore, in order to suppress amplified spontaneous emission (ASE), multi-stage pulse pump technology was applied and different pumping characteristics had been measured. Finally, 15% extraction efficiency was obtained when output energy reached 33 mJ. Output capability of the amplifier was not limited by SBS and ASE but the pump peak power.

► We realized 33 mJ energy, 10 ns pulse width laser at lower than 20 Hz repetition rate.
► We demonstrate a broadband fiber laser system emitting 10 nm bandwidth.
► Multi-stage pulse pump technology is applied and different pumping characteristics have been obtained.