We propose orbital angular momentum (OAM) mode generation using an all-fiber coupler based on hollow-core circular photonic crystal fibers (PCF). Using the mode-matching method, we calculated the coupling efficiency of high-order vector modes excited by the OAM coupler. The coupler’s structure with optimal parameters was designed to achieve high mode purity and good coupling efficiency for broadband operation. By selecting the proper center-to-center distance and coupling length, the designed mode selective coupler (MSC) generated no more than third-order OAM mode coupling. The MSC’s maximum coupling efficiency was more than 51% and its mode purity was in excess of 52% across the entire C + L band. The OAM MSC’s design provides a key basis for constructing an all-fiber mode division multiplexing (MDM) communication system.

我们建议使用基于空心圆形光子晶体光纤（PCF）的全光纤耦合器来生成轨道角动量（OAM）模式。使用模式匹配方法，我们计算了由OAM耦合器激发的高阶矢量模式的耦合效率。设计了具有最佳参数的耦合器结构，以实现高模式纯度和宽带操作的良好耦合效率。通过选择适当的中心距和耦合长度，设计的模式选择耦合器（MSC）生成的不超过三阶OAM模式耦合。MSC的最大耦合效率超过51％，在整个C + L频段上，其模式纯度超过52％。OAM MSC的设计为构建全光纤模式分复用（MDM）通信系统提供了关键基础。