Single-size nanostructured metasurface for dual-channel vortex beam generation

Area of Science:

• Optics and Photonics
• Nanotechnology
• Information Technology

Background:

• Metasurfaces with anisotropic nanostructures enable nanoscale optical manipulation.
• Malus's law and orientation degeneracy offer design freedom for polarization multiplexing.
• Amplitude-modulated multiplexing meta-devices are crucial for advanced optical systems.

Purpose of the Study:

• To experimentally demonstrate a metasurface for encoding two independent amplitude profiles.
• To achieve dual-channel vortex beam generation with a single-size nanostructure design.
• To enable switching between two information channels by rotating the metasurface.

Main Methods:

• Utilizing anisotropic nanostructures as nano-polarizers on a metasurface.
• Leveraging orientation degeneracy in Malus's law for polarization multiplexing.
• Designing a single-size nanostructure to function as two independent fork gratings.

Main Results:

• Successfully encoded two independent amplitude profiles onto a single metasurface.
• Generated two vortex beams with different topological charges.
• Demonstrated switching between the two channels by rotating the metasurface from 0° to 45°.

Conclusions:

• The proposed metasurface offers high resolution, ultracompactness, and dual-channel information capacity.
• Ultrasimple nanostructures facilitate practical applications in information and OAM multiplexing.
• This technology has potential applications in quantum information processing and advanced communication systems.