All-Fiber OAM Generation/Conversion Using Helically Patterned Photonic Crystal Fiber

We propose an all-fiber orbital angular momentum (OAM) generator/converter based on photonic crystal fiber (PCF). The PCF is designed to introduce a helical effective refractive index profile in order to achieve the OAM matching condition that is required to excite the OAM modes of an OAM-supporting fiber. The proposed design is compact, presents wideband operation, low loss and high OAM purity. It is of great interest to OAM-based telecommunication, and other OAM applications that use optical fibers.