研究了基于级联单光纤耦合器(OC)和双OC光纤环的复合环形腔光纤激光器的单纵模运转特性。通过对级联单OC和 双OC光纤环辅腔的谐振通带特性进行分析,给出了优化双OC环的谐振通带特性以实现稳定单纵模运转的依据。 利用构建的这种复合环形腔光纤激光器,实验验证了该理论依据的正确性。当主腔腔长为6.8 m, 单OC环环长为0.45 m, 双OC环环长约为0.56 m时,选取双OC的耦合比为0.7, 单纵模运转的稳定性相对最好,实验与理论分析结果相吻合。

The single longitudinal mode (SLM) operation characteristics of a compound ring cavity fiber laser based on cascaded fiber rings formed by single and dual optical coupler (OC) was investigated. By analyzing the resonating pass-band properties of cascaded fiber rings with respectively single and dual OC, a method to optimize the resonating pass-band properties of the dual-OC fiber ring for achieving stable SLM operation was given. With a compound ring cavity erbium-doped fiber laser based on such cascaded fiber rings, the optimization method for achieving stable SLM operation was verified experimentally. For the length of the main ring, the single-OC ring and dual-OC ring are respectively 6.8, 0.45 and 0.56 m, the operation for SLM with the fiber laser is observed to be most steadily when the coupling ratio of the two OCs in the dual-OC fiber ring is chosen to be 0.7. The experimental results are in agreement with the theoretical analysis.