Spectral dynamics of pulsed diode-pumped erbium-doped fluoride fiber lasers

We present an experimental and computational investigation of the dynamics in singly Er-doped and Er/Pr-codoped double-clad fluoride fiber lasers that are pulse-pumped with diode at 975 nm. Measurements that include time-dependent laser power and spectrum show multi-line operation with distinct initial line jumping in the Er fiber and spectral and power fluctuations in both fibers. Thermal effects are dismissed as the cause and the effects of homogeneous and inhomogeneous broadenings on the laser operation are studied by using a simulation that is based on the rate-equations. Simulation results show line jumping with accurate timing in both homogeneous and inhomogeneous models, and the best match with the experiment is achieved with the inhomogeneous model assuming independent lasing of two distinct ion classes. (C) 2010 Optical Society of America