Spin-Orbit Interaction of Light in Plasmonic Lattices

Area of Science:

• Optics and Photonics
• Metamaterials and Plasmonics
• Light-Matter Interactions

Background:

• Spin-orbit interaction (SOI) of light is crucial for metamaterials and light-matter interactions.
• The spin-based plasmonic effect converts light's spin angular momentum to near-field orbital angular momentum.
• SOI has been studied in circular symmetry but not in noncircular geometries.

Purpose of the Study:

• To experimentally demonstrate SOI in nanostructures with dihedral symmetry.
• To investigate the behavior of the spin-based plasmonic effect in noncircular geometries.
• To explore the potential for creating optical nanomotors using engineered plasmonic fields.

Main Methods:

• Phase-resolved near-field microscopy was employed.
• Nanostructures with hexagonal slits and dihedral symmetry were used.
• Theoretical calculations of optical forces were performed.

Main Results:

• Demonstrated SOI of circularly polarized light in hexagonal nanostructures.
• Observed four topologically distinct plasmonic lattices controlled by boundary conditions.
• Revealed a cyclic spin-based plasmonic effect absent in circular symmetry.
• Calculated optical forces capable of generating torque for particle manipulation.

Conclusions:

• Engineered dihedral symmetry nanostructures exhibit novel SOI phenomena.
• The cyclic spin-based plasmonic effect offers new control mechanisms.
• Predicted the formation of optical nanomotor arrays for simultaneous particle manipulation and excitation.