Advanced Photonics Nexus, Volume. 2, Issue 2, 026001(2023)

Nondiffractive three-dimensional polarization features of optical vortex beams

Andrei Afanasev1、*, Jack J. Kingsley-Smith2, Francisco J. Rodríguez-Fortuño2, and Anatoly V. Zayats2
Author Affiliations
  • 1The George Washington University, Department of Physics, Washington, DC, United States
  • 2King’s College London, Department of Physics and London Centre for Nanotechnology, London, United Kingdom
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    Figures & Tables(6)
    Polarization parameters for a focused Laguerre–Gaussian vortex beam with l=1, linearly polarized along the x direction and propagating along the z axis. The beam waist is w0=λ. (a) The intensity distribution of the beam in the (xz) plane. (b–d) Colormaps of the (a) py, (b) pzz, and (d) pxx-pyy polarization parameters with polarization ellipses overlaid on top, indicating the polarization state at each point in space. The polarization structure around the phase singularity is nondiffractive and invariant with respect to the beam waist. The inserts in (c) show the cross-sections at different z positions. The insert in (d) shows the zoom near the beam centre.
    Polarization parameters for a focused Laguerre–Gaussian vortex beam with l=1and σ=−1 (left-hand circularly polarized), propagating along the positive z axis. The beam waist is (a–d) w0=λ and (e–h) w0=2λ. (a) and (e) The intensity distribution of the beam in the (xz) plane. (b–d) and (f–h) Colormaps of the (b,f) py, (c,g) pz, and (d,h) pzz polarization parameters with polarization ellipses overlaid on top, indicating the polarization state at each point in space. The polarization structure around the phase singularity is nondiffractive and invariant with respect to the beam waist.
    Cross sections of the linearly polarized vortex beams with w0=λ depicted in Fig. 1 showing (a) pzz and (b) |E|2 at the focal plane and after propagating a distance of 5λ. The vertical dashed lines show the points at which pzz=0 and the corresponding field intensity for each cross-section plane.
    (a) The angular spectrum of a linearly polarized (x direction) vortex beam with l=1. The green line indicates the light line and the red dotted line indicates the inner limit of the cropped region dictated by the objective with NA=0.5. (b) The intensity distribution of the corresponding vortex beam with NA=0.5 generated by integrating the field distribution in (a). The beam waist is w0=λ. (c) Colormap of the py polarization parameter with polarization ellipses overlaid on top, indicating the polarization state at each point in space. The nondiffractive behavior near the phase singularity is maintained and only peripheral fields are affected by the NA reduction. (d–f) The same quantities as in (a–c) but with part of the angular spectrum removed and astigmatism applied along x direction.
    (a–d) The phase of Ex in the focal plane of a nonparaxial l=3 vortex beam linearly polarized along x direction with w0=λ and (e–g) the pzz polarization parameter in a z=5λ plane (to avoid focal plane features) simulated for different finite numbers of constituent plane waves N (indicated in the panels). The l=3 vortex splits in three l=1 vortices with an increased splitting for a decreased N.
    • Table 1. Polarization parameters.

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      Table 1. Polarization parameters.

      Circular σ·l<0Circular σ·l>0LinearRadialAzimuthal
      η12(x^iy^)12(x^+iy^)x^ρ^ϕ^
      pz11+2ζ21000
      py2|ζ|cosϕ1+2ζ202|ζ|cosϕ1+ζ24|ζ|cosϕ1+4ζ20
      px2|ζ|sinϕ1+2ζ2004|ζ|sinϕ1+4ζ20
      pxxpyy0031+ζ23cos2ϕ1+4ζ23cos2ϕ
      pxy00032sin2ϕ1+4ζ232sin2ϕ
      pxz32|ζ|sinϕ1+2ζ203|ζ|sinϕ1+ζ200
      pyz32|ζ|cosϕ1+2ζ20000
      pzz14ζ21+2ζ2112ζ21+ζ218ζ21+4ζ21
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    Andrei Afanasev, Jack J. Kingsley-Smith, Francisco J. Rodríguez-Fortuño, Anatoly V. Zayats, "Nondiffractive three-dimensional polarization features of optical vortex beams," Adv. Photon. Nexus 2, 026001 (2023)

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    Paper Information

    Category: Research Articles

    Received: Nov. 9, 2022

    Accepted: Dec. 16, 2022

    Published Online: Mar. 1, 2023

    The Author Email: Andrei Afanasev (afanas@gwu.edu)

    DOI:10.1117/1.APN.2.2.026001

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