Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Layered Photonic Topological Insulators   The recent realization of photonic topological insulators has brought the
discovery of fundamentally new states of light and revolutionary applications
such as non-reciprocal devices for photonic diodes and robust waveguides for
light routing. The spatially distinguished layer pseudospin has attracted
attention in two-dimensional electronic materials. Here we report layered
photonic topological insulators based on all-dielectric bilayer photonic
crystal slabs. The introduction of layer pseudospin offers more dispersion
engineering capability, leading to the layer-polarized and layer-mixed photonic
topological insulators. Their phase transition is demonstrated with a model
Hamiltonian by considering the nonzero interlayer coupling. Layer-direction
locking behavior is found in layer-polarized photonic topological insulators.
High transmission is preserved in the bilayer domain wall between two
layer-mixed photonic topological insulators, even when a large defect is
introduced. Layered photonic topological insulators not only offer a route
towards the observation of richer nontrivial phases, but also open a way for
device applications in integrated photonics and information processing by using
the additional layer pseudospin.

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The categories of this paper are: econ
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
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The categories of this paper are: dg-ga
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The categories of this paper are: q-fin
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The categories of this paper are: q-bio
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The categories of this paper are: stat
2
The categories of this paper are: math
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The categories of this paper are: plasm-ph
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The categories of this paper are: nlin
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The categories of this paper are: hep-ex
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-th