High-efficiency plasmonic vortex generation with near-infrared bifunctional metasurfaces

Area of Science:

• Plasmonics
• Metasurfaces
• On-chip photonics

Background:

• Plasmonic vortices, with orbital angular momentum (OAM) and phase singularity, are key for on-chip photonics.
• Conventional vortex generators have low efficiency and limited functionality.

Purpose of the Study:

• To develop high-efficiency bifunctional metasurfaces for generating plasmonic vortices with distinct topological charges.
• To overcome the limitations of existing plasmonic vortex generation methods.

Main Methods:

• Designed and fabricated reflective meta-atoms with tailored resonant and geometric phases.
• Constructed a meta-coupler as a benchmark test.
• Developed bifunctional metasurfaces integrating both resonant and geometric phases.

Main Results:

• Demonstrated a meta-coupler generating a plasmonic vortex with 27% efficiency (56% simulated) at 1064 nm.
• Experimentally verified bifunctional metasurfaces generating divergent/convergent plasmonic vortices with distinct OAM using circularly polarized light of opposite helicity.
• Achieved efficient generation of tailored plasmonic vortices.

Conclusions:

• Established a systematic scheme for constructing high-efficiency bifunctional metasurfaces.
• Provided an efficient platform for generating desired plasmonic vortices for on-chip photonics.
• The developed metasurfaces offer enhanced functionalities and efficiency for OAM applications.