All-fiber focused optical vortex array generator based on a Dammann-Kinoform spiral zone plate.

An optical vortex array (OVA) provides more degrees of freedom for modulation by controlling the number and spatial distribution of optical vortices (OVs). However, traditional approaches such as spatial light modulation need to utilize numerous complex optical components to generate an OVA and bulky objective lenses to focus it. We reported a highly integrated all-fiber generator of the focused optical vortex array (FOVA) in this work. This generator was prepared by printing a Dammann-Kinoform spiral zone plate (DKSZP) on the fiber facet using femtosecond laser two-photon polymerization (TPP) nanoprinting. The DKSZP can convert the incident Gaussian beam into 1D or 2D FOVA. The focal length, spacing of optical vortices, and topological charge of the generated FOVA were designed and verified through simulation and experimentation. Notably, we have successfully achieved the capture and rotation of silica microsphere trimers, which is attributed to the multiple robust trapping sites carrying orbital angular momentum (OAM) provided by the generated FOVA. This achievement provides a novel solution for multi-target manipulation. Our results pave the way for the integration of FOVA generation devices, demonstrating great potential in applications such as particle manipulation, optical communication, optical metrology, and microfluidic pumps.