Subwavelength focusing of laser light of a mixture of  linearly and azimuthally polarized beams
S.S. Stafeev, A.G. Nalimov, M.V. Kotlyar, L. O’Faolain

 

Image Processing Systems Institute оf RAS, – Branch of the FSRC “Crystallography and Photonics” RAS, Samara, Russia,
Samara National Research University, Samara, Russia,
School of Physics and Astronomy of the University of St. Andrews

Full text of article: Russian language.

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Abstract:
We investigated a four-zone transmission polarization converter (4-TPC) for a wavelength of 633 nm, enabling the conversion of a linearly polarized incident beam into a mixture of linearly and azimuthally polarized beams. It was numerically shown that by placing a Fresnel zone plate of focal length  532 nm immediately after the 4-TPC, the incident light can be focused into an oblong subwavelength focal spot whose size is smaller than the diffraction limit (with larger and smaller size, respectively, measuring FWHM = 0.28λ  and FWHM = 0.45λ, where λ is the incident wavelength and FWHM stands for full-width at half maximum of the intensity). If after passing through a 4-TPC, light propagates in free space over a distance of 300 um before being focused by a Fresnel zone plate, the resulting  focal spot was found to measure 0.42λ and 0.81λ  (with the focal spot contributed to just by the transverse E-field components measuring 0.42λ and 0.59λ). This numerical result was verified experimentally, giving a focal spot of smaller and larger size, respectively, measuring 0.46λ and 0.57λ.

Keywords:
subwavelength micropolarizer, azimuthal polarization, subwavelength grating, tight focusing, near-field microscopy, FDTD, polarization selective devices.

Citation:
Stafeev SS, Nalimov AG, Kotlyar MV, O’Faolain L. Subwavelength focusing of laser light of a mixture of linearly and azimuthally polarized beams. Computer Optics 2016; 40(4): 458-466. DOI: 10.18287/2412-6179-2016-40-4-458-466.

References:

  1. Yu N, Capasso F. Flat optics with designer metasurfaces. Nature materials 2014; 13(2): 139-150. DOI:10.1038/nmat3839.
  2. Kildishev AV, Boltasseva A, Shalaev VM. Planar photonics with metasurfaces. Science 2013; 339(6125): 1232009. DOI: 10.1126/science.1232009.
  3. Kotlyar VV, Zalyalov OK. Design of diffractive optical elements modulating polarization. Optik 1996; 103(3): 125-130.
  4. Bomzon Z, Kleiner V, Hasman E. Pancharatnam-Berry phase in space-variant polarization-state manipulations with subwavelength gratings. Optics Letters 2001; 26(18): 1424-1426. DOI: 10.1364/OL.26.001424.
  5. Bomzon Z, Biener G, Kleiner V, Hasman E. Radially and azimuthally polarized beams generated by space-variant dielectric subwavelength gratings. Optics Letters 2002; 27(5): 285-287. DOI: 10.1364/OL.27.000285.
  6. Lerman GM, Levy U. Generation of a radially polarized light beam using space-variant subwavelength gratings at 1064 nm. Optics Letters 2008; 33(23): 2782-2784. DOI: 10.1364/OL.33.002782.
  7. Lerman GM, Levy U. Radial polarization interferometer. Optics Express 2009; 17(25): 23234-23246. DOI: 10.1364/OE.17.023234.
  8. Ghadyani Z, Vartiainen I, Harder I, Iff W, Berger A, Lindlein N, Kuittinen M. Concentric ring metal grating for generating radially polarized light. Applied Optics 2011; 50(16): 2451-2457. DOI: 10.1364/AO.50.002451.
  9. Xie Z, He J, Wang X, Feng S, Zhang Y. Generation of terahertz vector beams with a concentric ring metal grating and photo-generated carriers. Optics Letters 2015; 40(3): 359-362. DOI: 10.1364/OL.40.000359.
  10. Lin J, Genevet P, Kats MA, Antoniou N, Capasso F. Nanostructured holograms for broadband manipulation of vector beams. Nano Letters 2013; 13(9): 4269-4274. DOI: 10.1021/nl402039y.
  11. Genevet P, Capasso F. Holographic optical metasurfaces: a review of current progress. Reports on Progress in Physics 2015; 78(2): 024401. DOI: 10.1088/0034-4885/78/2/024401.
  12. Levy U, Tsai CH, Pang L, Fainman Y. Engineering space-variant inhomogeneous media for polarization control. Optics Letters 2004; 29(15): 1718-1720. DOI: 10.1364/OL.29.001718.
  13. Stafeev SS, O'Faolain L, Kotlyar VV, Nalimov AG. Tight focus of light using micropolarizer and microlens. Applied Optics 2015; 54(14): 4388-4394. DOI: 10.1364/AO.54.004388.
  14. Kotlyar VV, Stafeev SS, Kotlyar MV, Nalimov AG, O’Faolain L. Subwavelength micropolarizer in a gold film for visible light. Applied Optics 2016. 55(19): 5025-5032. DOI: 10.1364/AO.55.005025.
  15. Stafeev SS, Kotlyar MV, O’Faolain L, Nalimov AG, Kotlyar VV. Fourzone transmitted azimuthal micropolarizer with phase shift. Computer Optics 2016. 40(1): 12-18. DOI: 10.18287/2412-6179-2016-40-1-12-18.
  16. Davidson N, Bokor N. High-numerical-aperture focusing of radially polarized doughnut beams with a parabolic mirror and a flat diffractive lens. Optics Letters 2014; 29, 1318-1320. DOI: 10.1364/OL.29.001318.
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