Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonlinear frequency conversion and manipulation of vector beams in a
  Sagnac loop   Vector beams (VBs) are widely investigated for its special intensity and
polarization distributions, which is useful for optical micromanipulation,
optical micro-fabrication, optical communication, and single molecule imaging.
To date, it is still a challenge to realize nonlinear frequency conversion
(NFC) and manipulation of such VBs because of the polarization sensitivity in
most of nonlinear processes. Here, we report an experimental realization of NFC
and manipulation of VBs which can be used to expand the available frequency
band. The main idea of our scheme is to introduce a Sagnac loop to solve the
polarization dependence of NFC in nonlinear crystals. Furthermore, we find that
a linearly polarized vector beam should be transformed to an exponential form
before performing the NFC. The experimental results are well agree with our
theoretical model. The present method is also applicable to other wave bands
and second order nonlinear processes, and may also be generalized to the
quantum regime for single photons.

18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
32
The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph