Record-peak-power all-fiber single-frequency 1550 nm laser

In this paper, we present results on the amplification of 2 MHz linewidth nanosecond pulses in a recently developed ytterbium-free erbium-doped large mode area fiber cladding pumped at 980 nm. A record peak power of 4 kW for single-frequency single-mode silica-based fiber sources near 1550 nm is demonstrated. Pulse instabilities arising in an all-fiber laser scheme from stimulated Brillouin scattering are described.