Cross-connection of multiplexed cylindrical vector beams using off-axis spin-decoupled metasurfaces

Area of Science:

• Optoelectronics and Photonics
• Optical Communication Networks

Background:

• Cylindrical vector beam (CVB) multiplexing is crucial for advanced communication networks.
• Existing methods for CVB mode (de)multiplexing face challenges in cross-connection, including multi-mode conversion and polarization control.

Purpose of the Study:

• To present a novel strategy for independent off-axis spin-orbit interaction for CVB mode cross-connection.
• To overcome limitations of current cross-connection techniques in CVB communication.

Main Methods:

• Utilized spin-decoupled metasurfaces to achieve independent off-axis spin-orbit interaction.
• Encoded conjugated Dammann optical vortex grating phases onto orthogonal circularly polarized components of CVBs for cross-connection.
• Employed a silicon-based metasurface for experimental demonstration.

Main Results:

• Successfully demonstrated interconversion of four CVB modes (CVB₊₁ ↔ CVB_-2, CVB₊₂ ↔ CVB_-4).
• Achieved a polarization conversion efficiency exceeding 85%.
• Facilitated cross-connection of 200 Gbit/s quadrature phase-shift keying signals with bit-error-rates below 10^-6.

Conclusions:

• The proposed spin-orbit interaction strategy with metasurfaces enables efficient CVB mode cross-connection.
• This approach offers advantages like ultra-compact device size, flexible mode control, and multi-mode parallel processing.
• The technique shows significant potential for enhancing CVB mode multiplexing communication networks.