Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High-power mid-infrared frequency comb source based on a femtosecond
  Er:fiber oscillator   We report on a high-power mid-infrared frequency comb source based on a
femtosecond Er:fiber oscillator with a stabilized repetition rate at 250 MHz.
The mid-infrared frequency comb is produced through difference frequency
generation in a periodically poled MgO-doped lithium niobate crystal. The
output power is about 120 mW with a pulse duration of about 80 fs, and spectrum
coverage from 2.9 to 3.6 um. The coherence properties of the produced
high-power broadband mid-infrared frequency comb are maintained, which was
verified by heterodyne measurements. As the first application, the spectrum of
a ~200 ppm methane-air mixture in a short 20 cm glass cell at ambient
atmospheric pressure and temperature was measured.

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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-ex
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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: nucl-th
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The categories of this paper are: stat
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The categories of this paper are: q-bio
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The categories of this paper are: eess
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The categories of this paper are: hep-lat
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-th
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
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The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: patt-sol