Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Improving the beam quality factor ($M^2$) by phase-only reshaping of
  structured light   Laser brightness is crucial in many optical processes, and is optimised by
high power, high beam quality (low $M^2$) beams. Here we show how to improve
the laser beam quality factor (reducing the $M^2$) of arbitrary structured
light fields in a lossless manner using continuous phase-only elements, thus
allowing for the increase in brightness by a simple linear optical
transformation. We demonstrate the principle with four high $M^2$ initial
beams, converting each to a Gaussian ($M^2 \approx 1$) with a dramatic increase
in brightness of $>10 \times$. This work puts a new perspective on the old
debate of improving laser beam quality with binary diffractive optics, while
providing a practical approach to enhancing laser brightness for arbitrary
input beams.

34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg