Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Analytical coupled-wave model for photonic crystal quantum cascade
  lasers   A coupled-wave model is developed for photonic-crystal quantum cascade
lasers. The analytical model provides an efficient analysis of full
three-dimensional large-area device structure, and the validity is confirmed
via simulations and previous experimental results.

31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
1
The categories of this paper are: cs
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph