Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Manipulation of Orbital Angular Momentum Spectrum Using Shape-Tailored
  Metasurfaces   Vortex beams carrying orbital angular momentum (OAM) have been widely applied
in various electromagnetic, optical, and quantum systems. A tailored OAM
spectrum composed of several specific modes as expected holds a promise for
expanding the degrees of freedom of the systems. However, such a broadband
high-purity tailored spectrum is difficult to be achieved by the present
devices, where the broadband amplitude manipulation has not been explored yet.
In this work, inspired by the envelope-modulation theory, an elegant and
universal way to manipulate the OAM spectrum in wide bandwidth is proposed by
using a shape-tailored metasurface. Firstly, the rotating meta-atoms on a
triangular lattice are proved to have smaller coupling distortion than that on
a square lattice, and this behavior is critical for high-purity vortex spectrum
generation by the Pancharatnam-Berry-based metasurfaces. Secondly, a universal
modulation relation is established between the spatial arrangement of
metasurfaces and the generated vortex beams. Finally, the broadband modulated
OAM spectra and the comb-like OAM spectra are theoretically and experimentally
demonstrated by the shape-tailored metasurfaces. The proposed
amplitude-modulation scheme offers a novel concept and engineering route to
manipulate the OAM spectrum in wide bandwidth, which could promote the
development of OAM-based applications.

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The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
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The categories of this paper are: funct-an
16
The categories of this paper are: stat
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The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
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The categories of this paper are: acc-phys
2
The categories of this paper are: math
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The categories of this paper are: adap-org
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The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol
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The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an