Nanosecond pulse pumped, fiber-integrated narrow linewidth linearly polarized Raman amplifier at 1120 nm

In this manuscript, we demonstrated a watt-level average power narrow linewidth linearly polarized fiber-integrated Raman amplifier core pumped by a pulsed laser with center wavelength of 1064 nm. The gain medium in the amplifier stage is a 100-meters-long polarization-maintaining (PM) single-mode fiber. Seeded by a single-frequency (S-F) distributed feedback (DFB) diode laser, ~3.2 ns duration tunable 1120 nm laser is obtained with peak power of ~360 W. The average power of the Raman laser are 0.62W, 1.22 W and 1.83W with repetition rates of 500 KHz, 1 MHz and 1.5 MHz, respectively. More than 50% slope efficiency and 42 dB amplification is achieved. The polarization extinction rate (PER) of the Raman laser is measured to be ~21 dB.