Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High-Efficiency, Extreme-Numerical-Aperture Metasurfaces Based on
  Partial Control of the Phase of Light   High-quality flat optical elements require efficient light deflection to
large angles and over a wide wavelength spectrum. Although phase gradient
metasurfaces achieve this by continuously adding phase shifts in the range of 0
to 2{\pi} to the electric field with subwavelength-sized scatterers, their
performance is limited by the spatial resolution of phase modulation at the
interface. Here, we introduce a new class of metasurfaces based on a general
formulation, where the phase shifts cover less than the full 0-2{\pi} range,
offering significant advantages. More specifically, this approach allows the
realization of metasurfaces with more compact and less mutually-interacting
scatterers, thus more precise phase modulation, and advances the performance
limits of metasurfaces to domains significantly beyond those of the full
coverage phase gradient approach. Applying this concept to both plasmonic and
dielectric surfaces, we demonstrate large phase gradients resulting in
high-numerical-aperture immersion metalenses (NA=1.4) with near
diffraction-limited resolution (~0.32{\lambda}) at visible wavelengths. Our
concept enables added functionalities such as a broadband performance and
wavelength de-multiplexing on a single layer, surpassing the theoretical
cross-polarization transmission efficiency limit for single-layer plasmonic
metasurfaces, and yields 67% efficiency for dielectric metasurfaces. This work
paves the way toward realizing high-resolution flat optical elements and
efficient plasmonic metadevices.

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The categories of this paper are: q-bio
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The categories of this paper are: atom-ph
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The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-alg
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The categories of this paper are: hep-lat
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The categories of this paper are: comp-gas
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The categories of this paper are: supr-con
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The categories of this paper are: hep-ex
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The categories of this paper are: stat
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The categories of this paper are: nlin
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The categories of this paper are: gr-qc
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The categories of this paper are: chao-dyn
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The categories of this paper are: ao-sci
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The categories of this paper are: alg-geom