Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Determining the twist in an optical fiber   We determine the twist in a birefringent optical fiber from measurements, at
one end of the fiber, of the fiber response to an impulsive source at the same
end. This is the inverse problem of determining a non-constant coefficient, of
a first order hyperbolic system in one space dimension with two speeds of
propagation, from measurements at one end of an interval, of the solution of
this system corresponding to an impulsive source at the same end. We prove a
stability result for this inverse problem and give a provable reconstruction
algorithm for this inverse problem.

6
The categories of this paper are: astro-ph
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The categories of this paper are: cmp-lg
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
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The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
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The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
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The categories of this paper are: nlin
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The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph