Zhao Xinyi, Zhao Yunhe, Liu Yunqi, Liu Zuyao, Mou Chengbo, Shen Lei, Zhang Lei, Luo Jie
Appl Opt. 2020 Dec 1;59(34):10688-10694. doi: 10.1364/AO.408782.
We demonstrate high-order mode conversion in a few-mode fiber (FMF) via laser inscribed long-period fiber gratings (LPFGs) at both the 1.55 µm and 2 µm wavebands. At the 1.55 µm waveband, five high-order core modes (the , , , , and modes) can be coupled from the mode with high efficiency by the FMF-LPFGs. The orbital angular momentum beams with different topological charges (±1,±2,±3) are experimentally generated by adjusting the polarization controllers. At the 2 µm waveband, three high-order modes (the , , and mode) can be coupled by the FMF-LPFGs with different grating periods. The proposed LPFG-based mode converters could have a potential prospects in mode-division multiplexing and multiwindow broadband optical communication applications.
我们通过在1.55 µm和2 µm波段的激光写入长周期光纤光栅（LPFG）在少模光纤（FMF）中演示了高阶模式转换。在1.55 µm波段，五个高阶纤芯模式（、、、和模式）可以通过FMF-LPFG从模式高效耦合。通过调整偏振控制器，实验产生了具有不同拓扑电荷（±1、±2、±3）的轨道角动量光束。在2 µm波段，三个高阶模式（、和模式）可以通过具有不同光栅周期的FMF-LPFG进行耦合。所提出的基于LPFG的模式转换器在模分复用和多窗口宽带光通信应用中可能具有潜在的前景。
