Hybrid refractive-diffractive vortex beam generator integrated on a fiber tip.

Vortex beams (VBs) carrying orbital angular momentum have attracted widespread interest for applications in optical communication, imaging, and manipulation, yet their generation still mainly relies on bulky optical components that hinder miniaturization and integration. Here, we propose a fiber-integrated hybrid refractive-diffractive device for high-efficiency and high-fidelity VB generation. Using a one-step two-photon polymerization process, a hyperbolic aspherical lens (HAL) for beam collimation and diffraction modulators for vortex phase shaping are monolithically integrated on the fiber tip. This approach supports both spiral phase plates and vortex gratings, enabling versatile VB generation. Optical characterization shows that the fiber-tip HAL achieves a magnification of 13.4× with a collimation angle of 0.38°. Far-field interference measurements confirm the generation of a coaxial VB and off-axis VB arrays. This fully fiber-integrated platform offers a scalable and efficient solution for VB applications in space-constrained photonic systems.