Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Polarization properties in the transition from below to above lasing
  threshold in broad-area vertical-cavity surface-emitting lasers   For highly divergent emission of broad-area vertical-cavity surface-emitting
lasers (VCSELs) a rotation of the polarization direction by up to 90 degrees
occurs when the pump rate approaches the lasing threshold. Well below threshold
the polarization is parallel to the direction of the transverse wave vector and
is determined by the transmissive properties of the Bragg reflectors that form
the cavity mirrors. In contrast, near-threshold and above-threshold emission is
more affected by the reflective properties of the reflectors and is
predominantly perpendicular to the direction of transverse wave vectors. Two
qualitatively different types of polarization transition are demonstrated: an
abrupt transition, where the light polarization vanishes at the point of the
transition, and a smooth one, where it is significantly nonzero during the
transition.

24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas