Fabrication and characterization of erbium‐doped silica single‐mode fibers

Abstract

AbstractThis paper discusses erbium‐doped (Er‐doped) optical‐mode silica fibers for which vigorous research efforts have been carried out in recent years. The fabrication techniques and the amplification characteristics with semiconductor lasers used as the excitation source are investigated. As the fabrication of Er‐doped optical fibers, the vapor axial deposition (VAD) method, which is one of the fiber manufacturing techniques, is used. The rare earth doping into the porous material (in vapor phase) by using this method and the possibility of controlling the Er concentration (up to about 1000 ppm) are considered.As the evaluation of amplification characteristics, experimental results of the dependencies upon the pumping wavelength and Er concentration are presented. In particular, in regard to the dependency upon the Er concentration, which is quite important in highly efficient amplifiers, it is shown that there is a serious degradation in the amplification characteristics when the concentration is increased, even at the low doping level of 500 ppm. The deteriorative mechanisms also are discussed.