Controlling plasmonic orbital angular momentum by combining geometric and dynamic phases

TL;DR

This paper demonstrates a method to precisely control the orbital angular momentum of surface plasmon polaritons using metasurfaces that combine geometric and dynamic phases, enabling advanced manipulation for various optical applications.

Contribution

It introduces a novel approach to manipulate SPP OAM by integrating geometric and dynamic phases through metasurface design, allowing arbitrary OAM control.

Findings

Achieved tunable OAM of SPPs with designed metasurfaces.

Controlled spin-dependent and independent OAM components.

Potential applications in optical trapping, imaging, and quantum information.

Abstract

Tunable orbit angular momentum (OAM) of surface plasmon polaritons (SPPs) is theoretically studied with appropriately designed metasurfaces. By controlling both the orientation angle and spatial position of nano aperture array on an ultrathin gold film, the field distributions of the surface waves can be engineered to contain both spin dependent and independent OAM components. Simultaneous control over the geometric phase and optical path difference induced phase (dynamic phase) provides extra degrees of freedom for manipulating OAM of SPPs. We show that arbitrary combination of OAM numbers can be realized for the SPPs excited by incident light of different circular polarizations. The results provides powerful control over the OAM of SPPs, which will have potential applications on optical trapping, imaging, communications and quantum information processing.