Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical vortex trajectories in an astigmatic and elliptical Gaussian
  beam   An optical vortex, produced at one point in an optical beam, would propagate
through an optical system to another point where the vortex can be used for
some purpose. However, asymmetrical optical elements in such a system can cause
astigmatism or at least distroy the rotational symmetry of the beam, which may
affect the propagation of the vortex in an undesirable way. While an optical
vortex in a rotationally symmetric, stigmatic Gaussian beam retains its initial
morphology for as far as it propagates, the morphology of an optical vortex in
an asymmetric or astigmatic Gaussian beam changes. The vortex can even be
replaced by another with the opposite topological charge. We consider the
behavior of single noncanonical vortices propagating in Gaussian beams that are
asymmetric and/or astigmatic. General expressions for the vortex trajectories
are provided. The locations of the flip planes and the evolution of the
anisotropy of the vortex are considered for different non-ideal situations.

16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph