Perfect optical vortex microlenses fabricated via direct laser writing

Area of Science:

• Optics and Photonics
• Micro-optics
• Laser Fabrication

Background:

• Optical vortex beams carry orbital angular momentum, enabling applications in optical manipulation and communication.
• Generating stable and high-quality optical vortices with suppressed sidelobes remains a challenge.

Purpose of the Study:

• To demonstrate novel perfect optical vortex microlenses (POVMLs) using 3D direct laser writing.
• To achieve precise control over focal spot characteristics, including intensity distribution and stability.

Main Methods:

• Fabrication of POVMLs utilizing a 3D direct laser writing technique.
• Precise design and implementation of phase distribution on the microlenses.
• Experimental characterization of the generated vortex focal spots.

Main Results:

• Successful generation of stable bright rings (vortex focal spots) at the focal plane.
• Suppressed sidelobe intensity (<10% of main lobe) while maintaining topological charge up to 7.
• Consistent vortex focal spot radius (5.7 µm average) with high stability (1.94% RSD) and low deviation from simulations (5.3%).

Conclusions:

• 3D direct laser writing is an effective method for fabricating high-performance POVMLs.
• The demonstrated POVMLs offer superior robustness and stability for generating optical vortex beams.
• These findings pave the way for advanced applications requiring controlled optical vortex generation.