High-power narrow-linewidth Er(3+)-doped fiber laser.

We describe a high-power Er(3+) laser that produces 56 +/- 2 and 96 +/- 5 mW of power at room and liquid-nitrogen temperatures, respectively. Slope efficiencies of 10 +/- 1% and 14 +/- 1% with corresponding thresholds of 44 +/- 4 and 6.8 +/- 0.6 mW are obtained at high and low temperatures. An intracavity étalon composed of the output mirror and the fiber end face restricted the output linewidth to 620 +/- 60 MHz.