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Generation of perfect vortex beams by dielectric geometric metasurface for visible light

Published

Author(s)

Qianwei Zhou, Mingze Liu, Wenqi Zhu, Lu Chen, Yongze Ren, Henri Lezec, Yanqing Lu, Ting Xu, Amit Agrawal

Abstract

Perfect vortex beam (PVB) is a propagating optical field carrying orbital angular momentum (OAM) with a radial intensity profile that is independent of topological charge. PVB can be generated through the Fourier transform of a Bessel-Gaussian beam, which typically requires a well-aligned optical setup consisting of a spiral phase plate, an axion, and a lens. Here, based on a single-layer dielectric metasurface, we demonstrate the broadband generation of PVBs across the entire visible spectrum. The metasurface is composed of TiO2 nanopillars acting as deep-subwavelength half-waveplates, and able to provide the desired geometric phase profile to an incident circularly polarized light for the generation of PVBs. Through rigorous optimization of the nanopillars' structural parameters, we experimentally generate vortex beams carrying OAM with different topological charges that exhibit constant radial intensity profiles, verifying their "perfect" characteristics. Furthermore, we also demonstrate that the ellipticity and diameter of a PVB can be simultaneously controlled by adjusting the structural parameters of the metasurface, which further increases the flexibility in their design. These results open a new route towards creating ultra-compact, flat, multifunctional nanophotonic platforms for efficient generation of structured light beams.
Citation
Laser & Photonics Reviews
Volume
15
Issue
12

Citation

Zhou, Q. , Liu, M. , Zhu, W. , Chen, L. , Ren, Y. , Lezec, H. , Lu, Y. , Xu, T. and Agrawal, A. (2021), Generation of perfect vortex beams by dielectric geometric metasurface for visible light, Laser & Photonics Reviews, [online], https://doi.org/10.1002/lpor.202100390, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932952 (Accessed July 3, 2022)
Created October 31, 2021, Updated March 15, 2022