Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Solitons in thermal media with periodic modulation of linear refractive
  index   We address the existence and properties of solitons in thermal media with
periodic modulation of linear refractive index. Many kinds of solitons in such
optical lattices, including symmetric and antisymmetric lattices, are found
under different conditions. We study the influence of the refractive index
difference between two different layers on solitons. It is also found that
there do not exist cutoff value of propagation constant and soliton power for
shifted lattice solitons. In addition, the solitons launched away from their
stationary position may propagate without oscillation when the confinement from
lattices is strong.

31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
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The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
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The categories of this paper are: funct-an
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The categories of this paper are: comp-gas
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
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The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys