Controlling the plasmonic orbital angular momentum by combining the geometric and dynamic phases

Area of Science:

• Photonics and Nanotechnology
• Plasmonics
• Metasurface Optics

Background:

• Surface plasmon polaritons (SPPs) are electromagnetic waves confined to the interface of a conductor and a dielectric.
• Orbit angular momentum (OAM) is a fundamental property of light and other waves, influencing their spatial characteristics.
• Metasurfaces offer precise control over light due to their subwavelength engineered structures.

Purpose of the Study:

• To theoretically investigate the tunable orbit angular momentum (OAM) of surface plasmon polaritons (SPPs).
• To explore the use of specifically designed metasurfaces for manipulating SPP OAM.
• To demonstrate arbitrary control over SPP OAM states.

Main Methods:

• Theoretical analysis of SPP propagation on ultrathin gold films.
• Design and simulation of nano aperture arrays on metasurfaces.
• Engineering of field distributions by controlling nano aperture orientation and position.
• Leveraging geometric phase and dynamic phase for OAM manipulation.

Main Results:

• Achieved tunable OAM for SPPs by designing metasurfaces.
• Engineered SPP field distributions with both spin-dependent and independent OAM components.
• Demonstrated simultaneous control over geometric and dynamic phases.
• Showcased the realization of arbitrary combinations of OAM numbers for SPPs.

Conclusions:

• Metasurfaces provide powerful control over the OAM of SPPs.
• The ability to tune SPP OAM opens possibilities for advanced optical applications.
• Potential applications include optical trapping, imaging, communications, and quantum information processing.