Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonlinear dual-core photonic crystal fiber couplers   We study nonlinear modes of dual-core photonic crystal fiber couplers made of
a material with the focusing Kerr nonlinearity. We find numerically the
profiles of symmetric, antisymmetric, and asymmetric nonlinear modes, and
analyze all-optical switching based on instability of the symmetric mode. We
also describe elliptic spatial solitons controlled by the waveguide boundaries.

23
The categories of this paper are: solv-int
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The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin