Multifunctional metasurface coding for visible vortex beam generation, deflection and focusing

Area of Science:

• Optics and Photonics
• Metamaterials
• Nanotechnology

Background:

• Vortex beams carry orbital angular momentum (OAM), featuring unique donut-shaped intensity and helical wavefronts.
• Applications include optical communication, nanoparticle manipulation, and quantum information.
• Existing methods for vortex beam generation have limitations in efficiency, design flexibility, and require separate components for deflection and refocusing.

Purpose of the Study:

• To propose a novel metasurface design for efficient vortex beam generation.
• To achieve simultaneous anomalous deflection and refocusing of vortex beams using a single metasurface.
• To overcome limitations of traditional vortex beam generation techniques.

Main Methods:

• A novel metasurface design based on resonant phase is proposed, utilizing nanocylinder radius variation for 2π phase coverage.
• The design employs superimposed encoding sequences based on Fourier convolution and metalens principles.
• Metasurface fabrication and characterization in the visible regime were performed.

Main Results:

• Efficient generation of vortex beams in the visible spectrum was achieved.
• Simultaneous anomalous deflection and refocusing of vortex beams were successfully demonstrated.
• The all-in-one multifunctional metasurface design integrates beam generation, deflection, and refocusing.

Conclusions:

• The proposed resonant phase metasurface offers a versatile platform for advanced vortex beam manipulation.
• This integrated approach provides new technological pathways for secure optical communication and quantum manipulation.
• The design overcomes previous limitations, paving the way for more compact and efficient optical systems.