Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Efficient Broadband Terahertz Generation from Organic Crystal BNA Using
  Near Infrared Pump   We are reporting on terahertz generation from organic crystal BNA using a
1.15 to 1.55 um near infrared pump. We observed a very large emission spectrum
extending up to 7 THz, compared to 2.5 THz from Ti:Sa pump in previous reports.
The maximum optical-to-THz conversion efficiency in our experiment was 0.8% at
1 kHz repetition rate and without saturation leading to a peak electric field
of 1 GV/m. Our results show pronounced phase matching privilege for intense
terahertz generation using a pump in the 1.15 to 1.25 um range where high
energy near infrared pump sources operate.

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The categories of this paper are: gr-qc
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The categories of this paper are: cs
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The categories of this paper are: alg-geom
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The categories of this paper are: bayes-an
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The categories of this paper are: econ
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The categories of this paper are: math
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-ex
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The categories of this paper are: chao-dyn
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The categories of this paper are: solv-int
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The categories of this paper are: nlin
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The categories of this paper are: chem-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: q-bio
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The categories of this paper are: ao-sci
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The categories of this paper are: patt-sol