Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Second-Order Nonlinear Mixing of Two Modes in a Planar Photonic Crystal
  Microcavity   Polarization-resolved second-harmonic spectra are obtained from the resonant
modes of a two-dimensional planar photonic crystal microcavity patterned in a
free-standing InP slab. The photonic crystal microcavity is comprised of a
single missing-hole defect in a hexagonal photonic crystal host formed with
elliptically-shaped holes. The cavity supports two orthogonally-polarized
resonant modes split by 60 wavenumbers. Sum-frequency data are reported from
the nonlinear interaction of the two coherently excited modes, and the
polarization dependence is explained in terms of the nonlinear susceptibility
tensor of the host InP.

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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: cond-mat
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The categories of this paper are: astro-ph
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The categories of this paper are: q-alg
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The categories of this paper are: adap-org
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The categories of this paper are: gr-qc
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The categories of this paper are: comp-gas
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The categories of this paper are: acc-phys
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The categories of this paper are: cmp-lg
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-ex
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The categories of this paper are: eess
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The categories of this paper are: q-fin
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The categories of this paper are: plasm-ph
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The categories of this paper are: math-ph