Efficient point-by-point manipulated visible meta-vortex-lenses with arbitrary orbital angular momentum

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Orbital angular momentum (OAM) in light, carried as optical vortices, is of significant interest.
• Conventional methods for generating optical vortices often rely on bulky or costly equipment, hindering system integration.

Purpose of the Study:

• To demonstrate efficient, large-area, wavelength-thick metasurfaces for generating high-quality optical vortices with arbitrary OAM.
• To investigate the focusing capabilities and characteristics of these metasurfaces, specifically the relationship between OAM and focal ring properties.

Main Methods:

• Fabrication of wavelength-thick metasurfaces with nanoantenna structures.
• Characterization of optical vortex generation and beam focusing.
• Quantitative analysis of nanoantenna coupling effects and chromatic aberrations.

Main Results:

• Metasurfaces efficiently produce optical vortices with arbitrary OAM and focus them into wavelength-scale rings with up to 80% efficiency.
• A linear increase in focal ring size and an inverse proportional decrease in peak focusing intensity were observed with increasing OAM.
• Total energy within the focal rings remained largely constant across different OAM values.

Conclusions:

• The developed metasurfaces offer a compact and efficient solution for generating and focusing optical vortices.
• The findings provide a fundamental understanding of OAM-dependent focusing characteristics, crucial for advanced optical applications.
• These metasurfaces hold promise for applications in optical tweezers and optical communications.