Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: High-efficiency grating couplers for pixel-level flat-top beam
  generation
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ