Reconstructing a plasmonic metasurface for a broadband high-efficiency optical vortex in the visible frequency

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Metasurfaces, composed of 2D metallic nano-antenna arrays, can transform Gaussian beams into optical vortices by manipulating light's polarization and phase.
• This technology offers miniaturization of optical systems to wafer-scale components for diverse applications.
• Low conversion efficiency in generating vortex beams from circularly polarized light has been a significant limitation.

Purpose of the Study:

• To significantly improve the conversion efficiency of metasurfaces for generating optical vortex beams.
• To investigate factors influencing efficiency, including material choice, meta-atom geometry, spatial organization, and fabrication fidelity.
• To demonstrate a practical metasurface with enhanced efficiency in the visible frequency range.

Main Methods:

• Theoretical investigation using the Jones matrix method to analyze polarization and phase manipulation.
• Systematic calculations employing the finite difference time domain (FDTD) method to determine theoretical conversion efficiency.
• Fabrication of optimized metasurfaces based on theoretical parameters.

Main Results:

• Theoretical conversion efficiency exceeding 40% in the visible wavelength range was achieved.
• The fabricated metasurface demonstrated high-quality optical vortex generation.
• A broad waveband efficiency enhancement of over 20% was experimentally validated.

Conclusions:

• Metasurface design optimization significantly enhances optical vortex generation efficiency.
• The developed metasurfaces offer a promising solution for efficient optical vortex generation in the visible spectrum.
• This advancement opens new avenues for practical applications leveraging optical vortex beams.