Modeling and effects of ion pairs in high-concentration erbium-doped fiber lasers

According to the modeling of ion pairs in high-concentration erbium-doped fiber lasers, a closed form rate and power evolution equations containing isolated ions and ion pairs are constructed. Based on the equations, the effects of ion pairs on the output performance of high-concentration erbium-doped fiber lasers for low Q and high Q laser cavity in three different pump modes are analyzed numerically. The results show that with the increasing percentage of ion pairs, the output power and the slope efficiency decrease, and the threshold increases for each pump mode. Meanwhile, the backward pump mode is proved to be the best pump mode and the deleterious effects of ion pairs for low Q laser cavity is proved to be smaller than that for high Q laser cavity.