Conversion of Linear Polarized Light-to-Orbital Angular Momentum with Variable Topological Charges, Using the Surface Plasmons of Elliptical Holes Etched in a Gold Layer

Electromagnetic waves with a spiral phase front have orbital angular momentum (OAM), which have benefited tremendous applications in various fields, such as quantum information processing and optical manipulation. These particular beams can be applied in photonic integrated devices by using surface plasmon polaritons (SPPs) at metal-dielectric interface. Here, we present different arrays of elliptical holes inscribed in a gold layer, which can produce plasmonic vortices (PV) with arbitrary higher order of topological charges under linearly polarized light. Furthermore, in order to compare the quality of generated vortices, we have introduced a Figure of merit (FOM), which implies the field uniformity of the PVs.