Design of a sector-variant high-numerical-aperture micrometalens

Nalimov, Anton G.; Kotlyar, V. V.

doi:10.1016/j.ijleo.2018.01.046

Cited by 4 publications

(1 citation statement)

References 13 publications

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“…In this work, we study the use of 16 subwavelength gratings to generate an azimuthally polarized output beam with 16 gradations of the output polarization vectors, with the adjacent vectors making angles of 11.25°. In [26], a 16-sector micrometalens was demonstrated to generate a focal spot closest to the circle when illuminated by a linearly polarized beam.…”

Section: Computing An Optical Surface Of Spiral Metalensesmentioning

confidence: 99%

Sharp focusing of vector optical vortices using a metalens

Kotlyar

Nalimov

2018

J. Opt.

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Using an FDTD-simulation, we numerically show that a spiral metalens with topological charge m = 1, numerical aperture 1, and a focal length equal to the incident wavelength produces a tight near-surface focal spot shaped as a circle for incident TE-waves or a doughnut for TM-waves. It is also demonstrated numerically and theoretically that in the intensity pattern of the resulting focal spot there are local (symmetric and asymmetric) regions, which can be located both at its center or on the periphery, where the energy flux has the opposite direction. For example, the reverse energy flux is found to occur at m = 1 and left-handed circular polarization or at m = 2 and right-handed circular polarization. This effect can be used for moving a microparticle in the opposite direction to the beam propagation.

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Section: Computing An Optical Surface Of Spiral Metalensesmentioning

confidence: 99%

Sharp focusing of vector optical vortices using a metalens

Kotlyar

Nalimov

2018

J. Opt.

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Subwavelength grating-based spiral metalens for tight focusing of laser light

Kotlyar

Stafeev

Nalimov

et al. 2019

Applied Physics Letters

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In this paper, we investigate a 16-sector spiral metalens fabricated on a thin film (130 nm) of amorphous silicon, consisting of a set of subwavelength binary diffractive gratings and with a numerical aperture that is close to unity. The metalens converts linearly polarized incident light into an azimuthally polarized optical vortex and focuses it at a distance approximately equal to the wavelength of the incident light, λ = 633 nm. Using a scanning near-field optical microscope, it is shown experimentally that the metalens forms an elliptical focal spot with diameters smaller than the diffraction limit: FWHMx = 0.32λ (±0.03λ) and FWHMy = 0.51λ (±0.03λ). The experimental results are close to those of a numerical simulation using the FDTD method, with FWHMx = 0.37λ and FWHMy = 0.49λ. The technological errors due to manufacturing were taken into account in the simulation. This is the smallest focal spot yet obtained with a metalens.

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