Tunable 300 W single-frequency 2 micron fiber amplifier

arXiv:2510.05238v1 Announce Type: new
Abstract: We present an all-fiber design for a Tm-based fiber amplifier that can tune over 1992-2065 nm with 300-350 W single-frequency (2050 nm). Efficiencies of 55% are realized across the full bandwidth. Roll-off occurs beyond 2085 nm where ASE becomes intractable. The amplifier has an average M^2 value of 1.39 at high-power due to the presence of light guided within the fiber pedestal. Estimates of the pedestal light and higher-order mode contents are provided.