TEMPERATURE-DEPENDENCE OF THE GAIN IN ERBIUM-DOPED FIBERS

The temperature dependence of the gain in erbium-doped fibers between -20 and +85-degrees-C are discussed. The characteristics of three types of erbium-doped fibers with different erbium concentrations and glass compositions are investigated. The gain decreased with increasing temperature at the rate of -0.07 dB/degrees-C when pumped at 1.48-mu-m. The change in the gain was small when pumped at 0.98-mu-m. By measuring the change in the absorption and fluorescence spectra with temperature, we deduce that the change in the gain is due mainly to the change in the saturated population inversion.