Sharp focus of a circularly polarized optical vortex at the output of a metalens illuminated by linearly polarized light
A. G. Nalimovab, V. V. Kotlyarba
a IPSI RAS – Branch of the FSRC “Crystallography and Photonics” RAS,
Molodogvardeyskaya 151, 443001, Samara, Russia
b Samara National Research University, Moskovskoye Shosse 34, 443086, Samara, Russia
A three-level spiral metalens in an amorphous silicon film is designed. The metalens relief
consists of two subwavelength gratings with a $220$-nm period (for $633$ nm wavelength) and depths
of $90$ and $170$ nm. The metalens forms a left-hand circular polarized optical vortex with topological
charge $2$ when illuminated by a linearly polarized plane wave. The intensity distribution at a distance of $633$ nm is in the form of a subwavelength circle, whereas the longitudinal projection of the Pointing vector has negative values on the optical axis, meaning that a backward energy flow occurs. Two subwavelength gratings with different depth act as quarter-wave plates, transforming linearly polarized light into circularly polarized light with a phase delay of $\lambda/2$. This metalens combines functionalities of three optical elements: a quarter-wave plate, a spiral phase plate, and a high-NA diffraction metalens (NA close to unity).
optical vortex, polarization, quarter-wave plate, backward energy flow, metalens.
|Russian Foundation for Basic Research
|Ministry of Science and Higher Education of the Russian Federation
|This work was supported by the Russian Foundation for Basic Research under project No. 18-29-20003 (“Linear-to-circular polarization conversion using a subwavelength grating”), the RF Ministry of Science and Higher Education under the government project of the FSRC “Crystallography and Photonics”, RAS (“A metalens based on diffraction gratings serving as quarter-wave plates”).
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A. G. Nalimov, V. V. Kotlyar, “Sharp focus of a circularly polarized optical vortex at the output of a metalens illuminated by linearly polarized light”, Computer Optics, 43:4 (2019), 528–534
Citation in format AMSBIB
\by A.~G.~Nalimov, V.~V.~Kotlyar
\paper Sharp focus of a circularly polarized optical vortex at the output of a metalens illuminated by linearly polarized light
\jour Computer Optics
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