A compact, single-frequency, high-power, SBS-free, Yb-doped single-stage fiber amplifier

Interest in compact, single-frequency fiber amplifiers has increased within many scientific and industrial applications. The main challenge is the onset of nonlinear effects, which Bruit their power scaling. Here we demonstrate a compact, high power, single-frequency, polarization-maintaining, continuous-wave fiber amplifier using only one amplification stage. We developed the fiber amplifier using a master oscillator fiber amplifier architecture, where a low-noise, single-frequency, solid-state laser operating at 1064 nm was used as a seed source. We evaluated the amplifier's performance by using several state-of-the-art, small-core, Ytterbium (Yb)-doped fibers, as well as an in-house-made, highly Yb-doped fiber. An output power of 82 W was achieved with no sign of stimulated Brillouin scattering. A good beam quality and a polarization extinction ratio (PER) of > 25 dB were achieved. The compact fiber amplifier can be a competitive alternative to multi stage designed fiber amplifiers.