Non-interleaved geometric phase metasurfaces for low-crosstalk circular polarization multiplexing

Area of Science:

• Optics and Photonics
• Metamaterials Science

Background:

• Circular polarization multiplexing is crucial for optical information capacity but faces challenges like crosstalk and complex structures.
• Existing methods often require intricate designs or composite coding for spin-selective control.

Purpose of the Study:

• To develop a single-layer, non-interleaved geometric phase metasurface for effective decoupling of left- and right-handed circularly polarized (LCP/RCP) channels.
• To achieve spin-selective wavefront control with high polarization conversion efficiency and minimal crosstalk.

Main Methods:

• Utilizing Pancharatnam-Berry (PB) phase modulation with uniform PB-type anisotropic meta-units.
• Globally optimizing the in-plane orientation of meta-units for nonlocal orientation strategies.
• Performing full-wave simulations to verify holographic performance and crosstalk levels.

Main Results:

• Demonstrated a single-layer metasurface achieving polarization conversion efficiency near 99.99%.
• Successfully generated distinct holograms for LCP ('apple') and RCP ('mango') light with high fidelity.
• Confirmed minimal crosstalk between the decoupled LCP and RCP channels.

Conclusions:

• The proposed nonlocal orientation strategy offers a scalable, fabrication-friendly platform for dual-channel polarization encoding.
• This approach overcomes key challenges in circular polarization multiplexing, paving the way for advanced optical applications.
• Potential applications include optical encryption, holography, and quantum information processing.