Erbium-doped fiber amplifier pumped at 1.48 mu m with extremely high efficiency

An erbium-doped fiber amplifier pumped at 1.48 mu m with extremely high efficiency has been developed. The fiber has a relative refractive index difference of 2.0% and Er/sup 3+/ ions and alumina are doped only in a limited area of the core. A slope efficiency of 86% and a gain coefficient of 6.3 dB/mW have been achieved by 1.48 mu m pumping along with excellent spectral signal output performance. In spite of its small mode-field diameter, it is possible to fusion-splice the fiber to standard dispersion-shifted fibers with low loss due to diffusion of fluorine dopant in the classing.<
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