Perfect Optical Vortex Microlenses Fabricated via Direct Laser Writing

Abstract

In this work, we demonstrate perfect optical vortex microlenses (POVMLs) using a 3D direct laser writing technique. The POVMLs transform incident light into vortex focal spots, generating stable bright rings at the focal plane. By precisely designing and implementing the phase distribution, the POVMLs produce focal spots with significantly suppressed sidelobe intensity (less than 10% of the main lobe) while maintaining the topological charge up to 7. Experimental characterization demonstrates that the vortex focal spot maintains a consistent radius of 5.7 µm on average across different topological charges, exhibiting exceptional stability with a relative standard deviation (RSD) of merely 1.94%. The maximum deviation from theoretical simulations is limited to 5.3%, which clearly indicates the superior robustness of the focal spot radius against topological charge variations.