Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Vector Laguerre-Gauss beams with polarization-OAM entanglement in a
  graded-index medium   It is shown that the vector-vortex Laguerre-Gauss modes with
polarization-orbital angular momentum (OAM) entanglement are the vector
solutions of the Maxwell equations in a graded-index medium. Focusing of
linearly and circularly polarized vortex light beams with nonzero azimuthal and
radial indices in a cylindrical graded-index medium is investigated. The wave
shape variation with distance taking into account the spin-orbit and
nonparaxial effects is analyzed. Effect of long-term periodical revival of wave
packets due to mode interference in a graded-index cylindrical optical
waveguide is demonstrated. High efficiency transfer of a strongly focused spot
through an optical waveguide over large distances takes place with a period of
revival.

10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org