Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cylindrical Beam Propagation Modelling of Perturbed Whispering-Gallery
  Mode Microcavities   We simulate light propagation in perturbed whispering-gallery mode
microcavities using a two-dimensional finite-difference beam prop- agation
method in a cylindrical coordinate system. Optical properties of
whispering-gallery microcavities perturbed by polystyrene nanobeads are
investigated through this formulation. The light perturbation as well as
quality factor degradation arising from cavity ellipticity are also studied.

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The categories of this paper are: supr-con
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The categories of this paper are: comp-gas
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The categories of this paper are: mtrl-th
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The categories of this paper are: econ
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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: ao-sci
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The categories of this paper are: nlin
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The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: chem-ph
1
The categories of this paper are: cs
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The categories of this paper are: atom-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: astro-ph