Photobleaching of thulium-doped ZBLAN fibers with visible light.
Photobleaching of darkened thulium-doped ZBLAN fibers is observed after short exposure to visible light. The bleaching process is characterized by a stretched-exponential function of time with an exponent beta independent of both the bleaching intensity and the thulium concentration. The bleaching rate 1/ is also shown to scale linearly with the bleaching intensity and to have a 1/3 -power dependence on the thulium concentration. Incomplete and slow recovery of the color centers is observed in previously bleached fibers, suggesting the presence of at least two types of defect.
Laperle
P
P
Chandonnet
A
A
Vallée
R
R