All-Fiber-Integrated Narrowband Nanosecond Pulsed Tm-Doped Fiber MOPA

We present a high average power narrowband-pulsed fiber master oscillator power amplifier (MOPA) at 1.971 μm. The linewidth of the pulse trains is broadened to ~1.5 GHz via phase modulation. The repetition rates are 3 and 5 MHz, respectively. The output power of pulse train with 3 MHz repetition rate is 192 W, and the pulsewidth is 51 ns, corresponding to a peak power of 1.11 kW and a pulse energy of 62 μJ. The output power of pulse train with 5 MHz repetition rate is 209 W, and the pulsewidth is 46 ns, corresponding to a peak power of 0.86 kW and a pulse energy of 42 μJ. Higher output power can be achieved by narrowing the pulsewidth to several nanoseconds. To the best of our knowledge, this is the first demonstration on high-power narrowband nanosecondpulsed MOPA near 2 μm with an average power exceeding 200 W.