MIM Structure for optical vortex beam generator at nanoscale level

TL;DR

This paper presents a nanoscale plasmonic device that efficiently generates and controls optical vortex beams carrying orbital angular momentum, enabling integration into photonic systems.

Contribution

It introduces a novel metal-insulator-metal holey plasmonic vortex lens for generating tunable OAM beams at the nanoscale, demonstrated experimentally.

Findings

Successfully converts circularly polarized light into OAM beams

External control of OAM via light polarization handedness

Potential for large-scale integration of vortex emitters

Abstract

Optical beams carrying orbital angular momentum (OAM) can find tremendous applications in several fields. In order to apply these particular beams in photonic integrated devices innovative optical elements have been proposed. Here we are interested in the generation of OAM-carrying beams at the nanoscale level. We design and experimentally demonstrate a plasmonic optical vortex emitter, based on a metal-insulator-metal holey plasmonic vortex lens. Our plasmonic element is shown to convert impinging circularly polarized light to an orbital angular momentum state capable of propagating to the far-field. Moreover, the emerging OAM can be externally adjusted by switching the handedness of the incident light polarization. The device has a radius of few micrometers and the OAM beam is generated from subwavelength aperture. The fabrication of integrated arrays of PVLs and the possible simultaneous emission of multiple optical vortices provide an easy way to the large-scale integration of optical vortex emitters for wide-ranging applications.