Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonlinear optical beams carrying phase dislocations   We describe different types of self-trapped optical beams carrying phase
dislocations, including vortex solitons and ring-like soliton clusters. We
demonstrate numerically how to create such nonlinear singular beams by the
interaction of several fundamental optical solitons. Mutual trapping of several
solitons can be regarded as a synthesis of `soliton molecules', and it
corresponds to a transfer of an initial orbital angular momentum of a system of
solitons to a spin momentum of an optical vortex.

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The categories of this paper are: gr-qc
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The categories of this paper are: econ
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The categories of this paper are: q-bio
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The categories of this paper are: astro-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: hep-ex
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The categories of this paper are: mtrl-th
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The categories of this paper are: funct-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat
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The categories of this paper are: patt-sol
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The categories of this paper are: quant-ph