We report a new pulsed, narrow linewidth, single-mode, polarization maintaining (PM) all-fiber laser source in master
oscillator and power amplifier (MOPA) configuration that can operate over the C-band. The single-frequency pulsed
fiber laser seed was achieved by actively Q-switching a fiber laser using a piezo, with a wide pulse duration tuning range
of 7.5 ns - 1.24 μs. We use single-mode PM large core highly Er/Yb
co-doped phosphate glass fiber (LC-EYPhF) in the
power amplifier stage of MOPA to achieve 54 μJ/pulse for 153-ns pulses at 1538 nm with repetition rate of 20 kHz and
an estimated linewidth of ~ 5 MHz.
Power scaling of nanosecond fiber laser pulses with narrow linewidth has been demonstrated by using a new single-mode
(SM) large-core polarization maintaining (PM) highly Er/Yb co-doped phosphate glass fiber (EYPhF). We used an
optimized length of 12 cm of the EYPhF fiber in the power amplifier of the all-fiber MOPA chain. The pulse energy can
reach 0.11 mJ for the amplified pulsed fiber laser, which corresponds to a peak power of 51.5 KW with pulse duration of
2.1 ns and repetition rate of 5 KHz. This high power pulsed fiber laser has an estimated linewidth of < 500 MHz.