通过建立复合腔模型,分析了外光反馈对单纵模分布反馈式(DFB)光纤激光器稳定性的影响,研究了外光反馈引起的相干坍塌阈值特性。通过采用模式分裂表征方法和相位噪声表征方法,对DFB光纤激光器的相干坍塌现象进行了对照检测,成功测量了瑞利散射和端面反射分别引起单纵模DFB光纤激光器发生相干坍塌时工作纵模的分裂情况,证明只考虑瑞利散射时DFB光纤激光器的阈值传导光纤长度小于200m。实验结果和理论分析相吻合,验证了采用上述两种方法检测相干坍塌的可行性,对于DFB光纤激光传感阵列的结构设计具有指导意义。 The effect of the external light feedback on the stability of the single longitudinal mode distributed feedback (DFB) fiber laser is analyzed and the threshold characteristic of the coherent collapse caused by the external light feedback is studied. By using the mode splitting characterization method and the phase noise characterization method, the coherence collapsing phenomenon of DFB fiber lasers was checked, and the longitudinal mode of the longitudinal mode of the DFB fiber laser was measured when the Rayleigh scattering and the end reflection respectively caused the coherent collapse of the single longitudinal mode DFB fiber laser The splitting condition proves that the threshold conduction fiber length of DFB fiber laser is less than 200m considering only Rayleigh scattering. The experimental results are in good agreement with the theoretical analysis, which verifies the feasibility of using the above two methods to detect coherent collapse. It is instructive for the structural design of DFB fiber laser sensor array.