Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Generation of Orbital Angular Momentum by a Point Defect in Photonic
  Crystals
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org