Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Topological unidirectional guided resonances emerged from interband
  coupling   Unidirectional guided resonances (UGRs) are optical modes in photonic crystal
(PhC) slabs that radiate towards one side without the need for mirrors on the
other, represented from a topological perspective by the merged points of
paired, single-sided, half-integer topological charges. In this work, we report
a mechanism to realize UGRs by tuning the interband coupling effect originating
from up-down symmetry breaking. We theoretically demonstrate that a type of
polarization singularity, the circular-polarized states (CPs), emerge from
trivial polarization fields owing to the hybridization of two unperturbed
states. By tuning structural parameters, two half-charges carried by CPs evolve
in momentum space and merge to create UGRs. Our findings show that UGRs are
ubiquitous in PhC slabs, and can systematically be found from our method, thus
paving the way to new possibilities of light manipulation.

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The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys
6
The categories of this paper are: astro-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: q-fin
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: stat
10
The categories of this paper are: q-bio
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The categories of this paper are: nlin
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The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
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The categories of this paper are: econ