Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Micrometer-Thin Crystalline-Silicon Solar Cells Integrating Numerically
  Optimized 2-D Photonic Crystals
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol