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

摘要

We theoretically investigate the generation of far-field propagating opticalbeams with a desired orbital angular momentum by using an archetypicalmagnetoplasmonic tip surrounded by a gold spiral slit. The use of a magneticmaterial can lead to important implications once magneto-optical activity isactivated through the application of an external magnetic field. The physicalmodel and the numerical study presented here introduce the concept ofmagnetically tunable plasmonic vortex lens, namely a magnetoplasmonic vortexlens, which ensures a tunable selectivity in the polarization state of thegenerated nanostructured beam. The presented system provides a promisingplatform for a localized excitation of plasmonic vortices followed by theirbeaming in the far-field with an active modulation of both light'stransmittance and helicity.