Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Propagation-invariant vortex Airy beam whose singular point follows its
  main lobe   We propose and demonstrate a novel vortex Airy beam which is a superposition
of an Airy beam and its laterally sheared beam with a $\pi/2$ phase shift. This
new-type of vortex Airy beam exhibits stable propagation dynamics, wherein its
singular point closely follows its main lobe, unlike conventional vortex Airy
beams. Notably, the orbital angular mode purity of this new vortex Airy beam is
up to 10% better than that of a conventional vortex Airy beam. We anticipate
that this new type of vortex Airy beam, which combines the characteristics of
an optical vortex and a diffraction-free Airy beam, will facilitate new
directions in applications such as microscopy, material processing and
nonlinear optics.

1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int