Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Optical control of internal electric fields in band-gap graded InGaN
  nanowires
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
2
The categories of this paper are: math
29
The categories of this paper are: funct-an