Output saturation in a 980-nm pumped erbium-doped fiber amplifier

A fiber amplifier model is developed which includes a finite lifetime for the pumped level. Pump excited state absorption (ESA) from the pumped level is also included. The model is solved numerically for a erbiumdoped fiber amplifier pumped at 980 nm. The signal output power at 1.5 microm is found to be limited by the finite lifetime of the (4)I(11/2); ESA of the pump from the (4)I(11/2) further limits the signal output. Lifetimes of the (4)I(11/2) were measured for Er(3+) in a series of oxide and fluoride glasses. Output saturation is most important in the fluoride based glasses, where the (4)I(11/2) lifetime is longest.