Magnetic Control of Transmission and Helicity of Nano-Structured Optical Beams in Magnetoplasmonic Vortex Lenses

TL;DR

This paper presents a theoretical study of a magnetoplasmonic vortex lens that uses magnetic materials and external magnetic fields to actively control the polarization and orbital angular momentum of nanostructured optical beams.

Contribution

It introduces the concept of a magnetically tunable plasmonic vortex lens enabling active modulation of light's transmittance and helicity in nanostructured beams.

Findings

Magnetically activated magneto-optical activity enables tunable polarization control.

The system allows localized excitation and far-field beaming of plasmonic vortices.

Active modulation of light's transmittance and helicity demonstrated theoretically.

Abstract

We theoretically investigate the generation of far-field propagating optical beams with a desired orbital angular momentum by using an archetypical magnetoplasmonic tip surrounded by a gold spiral slit. The use of a magnetic material can lead to important implications once magneto-optical activity is activated through the application of an external magnetic field. The physical model and the numerical study presented here introduce the concept of magnetically tunable plasmonic vortex lens, namely a magnetoplasmonic vortex lens, which ensures a tunable selectivity in the polarization state of the generated nanostructured beam. The presented system provides a promising platform for a localized excitation of plasmonic vortices followed by their beaming in the far-field with an active modulation of both light's transmittance and helicity.