偏振耦合实现分布反馈光纤激光保偏输出

提出了一种通过偏振模式耦合方式实现分布反馈光纤激光器保偏输出的方法,分布反馈光纤激光器是由刻写在有源光纤上的相移光栅构成的一种窄线宽光源。由于侧面紫外曝光过程造成的光纤极化,这种光纤光栅激光具有线偏振特性,但光路结构一般是由单模光纤构成,因此激光的线偏振特性无法保持。通过监测激光偏振耦合输出功率,可以间接识别激光线偏振方向,将激光线偏振方向和保偏尾纤二次耦合熔接,可以实现窄线宽分布反馈光纤激光的保偏输出。实验得到了偏振消光比大于30 dB,输出稳定线偏振光的分布反馈光纤激光器,且激光效率、线宽、噪声等较原始单模输出时均未发生明显变化。

Polarization-maintaining output of distributed feedback fiber laser using polarization coupling method

In this study, a method for maintaining polarization- output of a distributed feedback fiber laser (DFB-FL) via polarization coupling method is proposed. DFB-FL is a type of narrow-line-width light source produced via phase shift grating etched on an active optical fiber. The grating formation process based on side exposure will induce the tangential index distribution polarization of the fiber, ensuring that the narrow-line-width laser exhibits single linear polarization characteristics. The output fiber of DFB-FL can be replaced with a polarization-maintaining fiber using the polarization-maintaining welding machine. During this process, the angle between the laser polarization direction and the slow axis of the polarization-maintaining fiber of DFB-FL can be adjusted by rotating the fiber. Moreover, the change in the laser power and polarization extinction ratio can be measured using a power meter and extinction ratio tester. When both the laser power and polarization extinction ratio are maximum, polarization coupling can be achieved between DFB-FL and the polarization-maintaining fiber. Results show that the polarization extinction ratio of the DFB-FL is greater than 30 dB and the polarization state is linearly polarized. Compared with the single-mode output fiber laser, the laser efficiency, line width, and noise of the polarization-maintaining output fiber laser show no significant changes.