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. A single longitudinal mode operation of a compound annular cavity fiber laser based on a cascaded single fiber coupler (OC) and a double OC fiber ring was investigated. By analyzing the resonant passband characteristics of cascaded single-OC and double-OC fiber ring auxiliary cavities, the resonant passband characteristics of dual OC ring are optimized to achieve stable single longitudinal mode operation.Based on the constructed complex ring Cavity fiber laser, the experimental verification of the theoretical basis of the correctness. When the length of the main cavity is 6.8 m, the length of the single OC ring is 0.45 m and the length of the double OC ring is about 0.56 m, the coupling ratio of the double OC is selected to be 0.7. The stability of the single longitudinal mode is relatively good. The theoretical analysis is consistent.