Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical vortex trapping and annihilation by means of nonlinear Bessel
  beams in nonlinearly absorbing media   In nonlinear Kerr media at intensities such that multiphoton absorption is
significant, a vortex of topological charge m in the center of a high-order
nonlinear Bessel beam (NBB) can be stable and subsist endlessly. We show that
the m-charged NBB is not only stable but is formed spontaneously from any other
n-charged NBB and N "foreign" vortices of total charge s randomly nested in the
beam cross section if n + s = m. All nested vortices merge in the center of the
original NBB, which undergoes a mode conversion to the NBB that preserves the
topological charge and the inward-directed power current that sustains the
diffraction-free and attenuation-free propagation in the medium with nonlinear
absorption. We foresee different applications such as the creation of stable,
multiply charged vortices without tight alignment requirements but by
spontaneous vortex combination, mixing waves or particles that the vortices can
guide, fast annihilation of vortex dipoles, and cleaning of speckled beams by
massive annihilation of vortices.

8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
0
The categories of this paper are: hep-ph
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph