Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High-power, high repetition rate, tunable, ultrafast vortex beam in the
  near-infrared   We report on experimental demonstration of high power, ultrafast, high
repetition rate vortex beam source tunable in the near-IR wavelength range.
Based on single-pass optical parametric generation of Yb-fiber laser of vortex
order lp=1 in a 50 mm long MgO doped periodically poled LiNbO3 crystal, the
source produces signal beam in vortex profile of order ls=1 across 1433-1553
nm. Additionally, the source produces broadband idler radiation tunable across
3379-4132 nm in the Gaussian beam profile. We observed that the vortex profile
of the pump beam is always transferred to the signal beam due to the highest
overlapping integral among the interacting beams and the idler maintains a
Gaussian spatial profile owing to conservation of orbital angular momentum in
optical parametric processes. For pump power of 4.72 W, the signal and idler
beams have maximum power of 1.7 W at 1509 nm and 0.48 W at 3625 nm
respectively. The signal vortex beam has output pulses of width 637 fs at a
repetition rate of 78 MHz. The signal (idler) has spectral width of 4.3 nm
(129.5 nm) and passive peak-to-peak power fluctuation better than 3% (1.1%)
over 30 minutes, respectively.

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The categories of this paper are: nucl-th
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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: q-bio
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The categories of this paper are: cond-mat
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex
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The categories of this paper are: cs
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The categories of this paper are: econ
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The categories of this paper are: plasm-ph
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The categories of this paper are: supr-con
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The categories of this paper are: hep-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: astro-ph
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The categories of this paper are: math
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The categories of this paper are: hep-ex