Clustering-induced nonsaturable absorption phenomenon in heavily erbium-doped silica fibers

Nonsaturable absorption experiments in heavily erbium-doped fibers demonstrate that the behavior of the absorption with pump power cannot be interpreted with an ion-pair model but requires that the presence of larger clusters be taken into account. Numerical modeling permits the determination of the percentage of ions organized in clusters, as much as 52% of the dopants in the tested fiber, and the intracluster transfer rate, up to 2 X 10(6) s(-1). (C) 1995 Optical Society of America