Encoding photonic angular momentum information onto surface plasmon polaritons with plasmonic lens

Area of Science:

• Optics and Photonics
• Quantum Information Science

Background:

• Angular momentum (AM) in photons, including spin (SAM) and orbital (OAM), is crucial for information encoding in classical and quantum optics.
• Surface plasmon polaritons (SPPs) are light-matter interactions on metal surfaces with potential for nanoscale optical applications.

Purpose of the Study:

• To demonstrate the encoding of photonic spin angular momentum (SAM) and orbital angular momentum (OAM) onto surface plasmon polaritons (SPPs).
• To investigate the influence of photonic AM on SPP near-field energy distribution using a nano-ring plasmonic lens.
• To explore the potential for removing spin degeneracy in photons via plasmonic interactions.

Main Methods:

• Excitation of a nano-ring plasmonic lens with photons possessing different combinations of SAM and OAM.
• Near-field energy distribution measurement using a near-field scanning optical microscope (NSOM).
• Numerical simulations and experimental validation of the observed phenomena.

Main Results:

• Both SAM and OAM of photons demonstrably influence the near-field energy distribution of SPPs.
• The energy distribution on the plasmonic lens surface is primarily determined by the absolute value of the total AM.
• Simultaneous encoding of photonic SAM and OAM information onto SPPs is achieved.
• The interaction between photonic OAM and the plasmonic lens effectively removes photon spin degeneracy.

Conclusions:

• SPPs can effectively carry both SAM and OAM information from incident photons.
• The nano-ring plasmonic lens provides a platform for manipulating and encoding photonic AM onto SPPs.
• These findings advance the fundamental understanding of photonic AM and offer pathways for designing novel plasmonic quantum optics devices.