Generation, Transmission, and Amplification of OAM Modes in the PbSe-Doped Ring-Core Fiber Carrying 3D Printed Spiral Phase Plate

Vortex beams carrying orbital angular momentum (OAM) have increasingly attracted attention in the field of optical communication. However, transmission is still an issue due to loss, especially fibers. In this work, we proposed, designed, and fabricated micro spiral phase plates (SPPs) directly on end facet a piece PbSe-doped ring-core fiber (RCF) through two-photon polymerization, realizing integration OAM beam generation, transmission, amplification. The prepared RCF comprises double-clad structure with core-clad refractive index difference 2.2% fluorescence range 1150 nm–1700 nm. intensity distribution interference fringes were obtained, which indicated that mode (|l|=1, 2, 3, 4) was generated transmitted within fiber. small-signal amplification four modes accomplished at 1550 nm under pump power 634 mW. on–off gain >13.2 dB for all differential (DMG) <1.7 dB. SPP-carrying demonstrates higher-order all-fiber systems.