Compared with end pumping fiber combiner, one of the advantages for side pumping combiner is the unlimited pumping points, which means multi-point or cascaded side pumping can be realized. However, the loss mechanism of the cascaded structure is rarely discussed. In this paper, we present the numerical and experimental investigation about the loss mechanism of a two-stage-cascaded side pumping combiner based on tapered-fused technique. The influence of loss mechanism on the coupling efficiency and thermal load of the fiber coating is analyzed according to simulations and experiments with different tapering ratios for the first stage. Based on the analysis, a cascaded component with total pump coupling efficiency of 96.4% handling a pump power of 1088 W is achieved by employing 1018 nm fiber laser as the pump source. Future work to further improve the performance of a cascaded side pumping combiner is discussed and prospected.

中文翻译：

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全光纤级联侧泵浦合路器的损耗机理

与端泵光纤合路器相比，侧泵光纤合路器的优点之一是泵浦点数不限，即可以实现多点或级联侧泵。然而，级联结构的损失机制很少被讨论。在本文中，我们提出了基于锥形融合技术的两级级联侧泵组合器的损耗机制的数值和实验研究。通过第一阶段不同锥度比的模拟和实验，分析了损耗机制对光纤涂层耦合效率和热负荷的影响。根据分析，采用 1018 nm 光纤激光器作为泵浦源，可实现总泵浦耦合效率为 96.4% 且泵浦功率为 1088 W 的级联组件。