Experimental demonstration of near-field focusing of a phase micro-Fresnel zone plate (FZP) under linearly polarized illumination

Mote, Rakesh G.; Yu, Siu Fung; Kumar, Ashwani; Zhou, Wei; Li, Xiao Feng

doi:10.1007/s00340-010-4210-8

Cited by 19 publications

(12 citation statements)

References 19 publications

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“…By way of illustration, the subwavelength focusing has been performed using planar plasmonic structures [1,2] or plasmonic lenses [3,4]. The tight focusing of laser light can also be achieved in the near-surface regions of conventional optical elements like a microaxicon [5], a ZP [6,7], a microlens [8], a solid immersion lens [9], and a conventional high NA lens [10][11][12][13]. The subwavelength focal spot can also be obtained on the tip of dielectric and metallic microcones [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Analysis of the shape of a subwavelength focal spot for the linearly polarized light

et al. 2013

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By decomposing a linearly polarized light field in terms of plane waves, the elliptic intensity distribution across the focal spot is shown to be determined by the E-vector's longitudinal component. Considering that the Poynting vector's projection onto the optical axis (power flux) is independent of the E-vector's longitudinal component, the power flux cross section has a circular form. Using a near-field scanning optical microscope (NSOM) with a small-aperture metal tip, we show that a glass zone plate (ZP) having a focal length of one wavelength focuses a linearly polarized Gaussian beam into a weak ellipse with the Cartesian axis diameters FWHM(x)=(0.44±0.02)λ and FWHM(y)=(0.52±0.02)λ and the (depth of focus) DOF=(0.75±0.02)λ, where λ is the incident wavelength. The comparison of the experimental and simulation results suggests that NSOM with a hollow pyramidal aluminum-coated tip (with 70° apex and 100 nm diameter aperture) measures the transverse intensity, rather than the power flux or the total intensity. The conclusion that the small-aperture metal tip measures the transverse intensity can be inferred from the Bethe-Bouwkamp theory.

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Section: Introductionmentioning

confidence: 99%

Analysis of the shape of a subwavelength focal spot for the linearly polarized light

et al. 2013

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“…A focal spot of size FWHM = 1.7λ (λ = 633 nm) was observed on a near-field microscope Ntegra (NT-MDT, 100-nm resolution) at distance z = 1.6 µm from the ZP, with the theoretically estimated size being FWHM = 0.54λ [2]. Focusing a linearly polarized 633-nm beam by means of a Fresnel ZP with 0.5-µm focus has been numerically simulated and experimentally studied [3]. The experimentally measured elliptic focal spot was equal to FWHM = 0.63λ on the minor semi-axis.…”

Section: Introductionmentioning

confidence: 99%

Tight focusing of laser light using a chromium Fresnel zone plate

et al. 2017

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Using near-field scanning microscopy, we demonstrate that a 15-µm zone plate fabricated in a 70-nm chromium film sputtered on a glass substrate and having a focal length and outermost zone's width equal to the incident wavelength λ = 532 nm, focuses a circularly polarized Gaussian beam into a circular subwavelength focal spot whose diameter at the fullwidth of half-maximum intensity is FWHM=0.47λ. This value is in near-accurate agreement with the FDTD-aided numerical estimate of FWHM=0.46λ. When focusing a Gaussian beam linearly polarized along the y-axis, an elliptic subwavelength focal spot is experimentally found to measure FWHMx=0.42λ (estimated value FWHMx=0.40λ) and FWHMy=0.64λ. The subwavelength focal spots presented here are the tightest among all attained so far for homogeneously polarized beams by use of non-immersion amplitude zone plates.

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“…Our recent work has shown that diffractive plasmonic planar lenses (DPL) with tuning metallic zones can support a higher resolution and narrower full-width half-maximum beam width than a dielectric planar lens does [6]. Otherwise, Fresnel zone plates (FZPs) are one kind of diffractive lens, which are circular diffraction gratings of alternate transparent and opaque zones, and are widely used as focusing lenses in applications in imaging, sensing, and microscopy to name a few [7][8][9]. Some works have shown that the FZPs with metal and dielectric material have a highly-direction focal beam with the focal size smaller than the diffraction limit in the visible wavelength region [10,11], furthermore, FZPs with metal-dielectirc multilayer are found to have better focuses [12].…”

Section: Introductionmentioning

confidence: 99%

Comparison of subwavelength focusing properties of diffraction and Fresnel zone plate plasmonic planar lenses

Feng

Zhang

Yang

2013

Optik

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Experimental demonstration of near-field focusing of a phase micro-Fresnel zone plate (FZP) under linearly polarized illumination

Cited by 19 publications

References 19 publications

Analysis of the shape of a subwavelength focal spot for the linearly polarized light

Analysis of the shape of a subwavelength focal spot for the linearly polarized light

Tight focusing of laser light using a chromium Fresnel zone plate

Comparison of subwavelength focusing properties of diffraction and Fresnel zone plate plasmonic planar lenses

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