基于干涉仪动态相移的光纤激光器跳模检测方法

Mode Hopping Detection for Fiber Laser Based on Dynamic Phase Changes in Interferometer

针对已有方法在单频光纤激光器跳模检测中存在的不足,提出一种基于非平衡光纤Michelson干涉仪动态相移的跳模检测方法。使用干涉仪将激光器跳模时的光频突变转换为相位工作点的突变,并通过同步监测相位工作点的正余弦函数两路信号来跟踪与判断它的动态相移,成功实现了对超窄线宽掺铒光纤环形激光器偶发的随机跳模以及由开机瞬态热效应触发的连续多次跳模的测量与分析。结果表明,该方法检测灵敏度高,跳模判据实时直观,并能测量跳模前后可能发生的频漂,为评价单频光纤激光器的模式稳定能提供有效的测试手段。

In order to solve the problems in mode hopping detection for single-frequency fiber lasers,a method is put forward based on the dynamic phase changes in an unbalanced Michelson fiber-optic interferometer.Steep frequency changes in mode hopping process are transformed to steep phase changes in the working point of the interferometer,and the changes are obtained accurately by tracking simultaneously both the sine and cosine functions of the working point in time domain.Various mode hops in an ultra-narrow linewidth erbium-doped fiber ring laser,including occasional hops and thermally-induced serial hops the moment the laser is switched on,have been detected successfully with this method.The results show that this method has a high testing sensitivity,and makes real-time and apparent criterions for identifying mode hops.Besides,possible frequency drift between two serial mode hops can also be measured by use of this method,which plays an effective role in evaluating the lasing mode stabilities of single-frequency fiber lasers.