Rotationally tunable polarization-insensitive metasurfaces for generating vortex beams

Fatih Balli, Mansoor A. Sultan, J. Todd Hastings

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

6 Scopus citations

Abstract

The orbital angular momentum (OAM) of light has been applied to a variety of areas such as optical tweezers, interferometry, and high-resolution microscopy.1, 2 Metasurfaces, two-dimensional engineered structures with subwavelength features, give access to tailored functionalities through highly efficient phase shifting and polarization conversion. However, conventional designs with a single metasurface element produce vortex beams with fixed OAM of ℓ∼ which limits the potential application areas. In this study, we propose and design a metasurface doublet lens structure having the property of generating variable modes controlled by the rotation angle. Inspired by Moiré-lenses, the proposed structure consists of two all-dielectric metasurfaces where the second lens has the reverse phase profile compared to the first one. This causes the cancellation of the total phase shift at the nominal position. In our design, we rotate the second element with a discrete set of angles from 0 to 5.6 degrees with respect to the optical axis and obtain a set of the modes from ℓ = 0 to 4. We demonstrate that the structure converts the input plane wave to the vortex beams with OAM modes as a function of the rotation angle. We model the unit cell structure working at wavelength 532 nm a with circular cross-section, fixed height and variable radius titanium dioxide nanopillar on a fused-silica substrate. Nanopillar locations are distributed in a square lattice form with subwavelength periodicity which is suitable for conventional microelectronics fabrication methods. We believe our design can be used in optical trapping to detect different sizes of micro-particles and to create reconfigurable microoptomechanical pumps.

Original languageEnglish
Title of host publicationMetamaterials, Metadevices, and Metasystems 2020
EditorsNader Engheta, Mikhail A. Noginov, Nikolay I. Zheludev
ISBN (Electronic)9781510637269
DOIs
StatePublished - 2020
EventMetamaterials, Metadevices, and Metasystems 2020 - Virtual, Online, United States
Duration: Aug 24 2020Aug 25 2020

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume11460
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceMetamaterials, Metadevices, and Metasystems 2020
Country/TerritoryUnited States
CityVirtual, Online
Period8/24/208/25/20

Bibliographical note

Funding Information:
This work was supported in part by Intel Engineering at the University of Kentucky.

Funding Information:
This work was supported in part by Intel Corporation and by the Reese S. Terry professorship in Electrical Engineering at the University of Kentucky.

Publisher Copyright:
© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

Keywords

  • Bessel beams
  • Orbital angular momentum of light
  • Tunable
  • Vortex beams

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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