Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Competition Between Intermodal Modulation Instability and Kerr Beam
  Self-cleaning in Graded-index Multimode Fiber   We report the suppression of intermodal modulation instability peaks as a
consequence of Kerr induced self beam-cleaning in a 90m long graded-index
multimode optical fiber under various specific launching conditions. The output
spectrum and the modal beam profiles for three modes (LP01, LP11, and LP21)
have been recorded for several values of pump pulse energy. Experimental
findings establish that the nonlinear coupling among the guided modes leads to
reshaping the output speckle pattern into a bell shape or higher-order
spatially clean beam profile as the pump peak power increases, whereas in
spectral-domain intermodal modulation instability peaks are observed whose
amplitude increases gradually to its maximum value and beyond certain threshold
power, the intermodal modulation instability peaks diminish. This suggests the
possibility to generate intermodal modulation instability free broadband
spectra at high pump peak powers.

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The categories of this paper are: nlin
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The categories of this paper are: astro-ph
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The categories of this paper are: eess
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs
16
The categories of this paper are: stat
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The categories of this paper are: hep-ph
29
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: alg-geom
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The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
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The categories of this paper are: patt-sol
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The categories of this paper are: econ
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The categories of this paper are: gr-qc
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The categories of this paper are: acc-phys