Indirect evaluation of active fiber parameters from the measurement of fiber laser threshold

The paper discusses the possibility to extract the most relevant active fiber parameters from the thresholds of fiber lasers built using spans of the fiber under test. This approach has been developed to allow designing high performance fibers laser with more specific and reliable data than those available in the literature for generic fibers, overcoming practical limitations due to the typical lack of details provided by fiber manufactures. Preliminary results have confirmed the usefulness of the devised procedure, which allowed predicting the optimal length that minimizes the threshold in excellent agreement with experiments. An analysis of the impact of the uncertainty in the extracted parameters is also provided.