Concentration effect on gain of Pr/sup 3+/-doped fluoride fiber for 1.3 mu m amplification

The concentration quenching mechanism in Pr/sup 3+/-doped fluoride fiber operating at the 1.3- mu m band is investigated. It is confirmed that the cooperative upconversion process causes signal gain saturation with pump power and degrades the gain characteristics of Pr/sup 3+/-doped fluoride fiber at a concentration of 1000 p.p.m. The reduction in gain coefficient due to cooperative upconversion is almost suppressed at a concentration of 500 p.p.m. A Pr/sup 3+/ concentration of 500 p.p.m. is a practical concentration for the fabrication of efficient Pr/sup 3+/-doped fluoride fiber amplifiers.<
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