Diode-pumped 1.7-W erbium 3-µm fiber laser

We report what is to our knowledge the first 3-mm fiber laser of the 1-W class. 1.7 W of output power and 17.3% slope eff iciency (with respect to the launched pump power) at a wavelength of 2.71 mm are demonstrated from a double-clad erbium-doped ZBLAN fiber diode pumped at 790 nm. Energy transfer from the Er3+ lower laser level to a Pr3+ codopant decreases ground-state bleaching and excited-state absorption, thus avoiding output-power saturation. This result represents more than an order-of-magnitude improvement over previous work of which we are aware. Advantages over current crystal-laser designs include nearly transverse fundamental-mode operation, reduced thermal effects, and ease of use, e.g., in medical endoscopy.