Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Buffering and Trapping Ultrashort Optical Pulses in Concatenated Bragg
  Gratings   Strong retardation of ultrashort optical pulses, including their deceleration
and stoppage in the form of Bragg solitons in a cascaded Bragg-grating (BG)
structure, is proposed. The manipulations of the pulses are carried out, using
nonlinear effects, in a chirped BG segment which is linked, via a defect, to a
uniform grating. The storage of the ultrashort pulses is shown to be very
robust with respect to variations of the input field intensity, suggesting the
feasibility of storing ultrafast optical pulses in such a structure. Physical
estimates are produced for the BGs written in silicon.

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The categories of this paper are: cond-mat
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The categories of this paper are: q-fin
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The categories of this paper are: solv-int
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The categories of this paper are: hep-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: math-ph
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The categories of this paper are: adap-org
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The categories of this paper are: funct-an
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The categories of this paper are: quant-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: eess
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The categories of this paper are: chem-ph
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The categories of this paper are: q-bio
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: patt-sol