Effects of concentration and clusters in erbium-doped fiber lasers

Abstract

We report a low-threshold, high-conversion-efficiency erbium-doped fiber laser in a 100-parts-in-106 fiber pumped at 1.48 μm. The threshold and efficiency are found to deteriorate noticeably as the erbium concentration is increased. We propose that this is due mostly to rapid cross relaxation between ion pairs or clusters, and through modeling we show that the cluster content increases with concentration.