Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical nonlinearity enhancement of graded metal-dielectric composite
  films   We have derived the local electric field inside graded metal-dielectric
composite films with weak nonlinearity analytically, which further yields the
effective linear dielectric constant and third-order nonlinear susceptibility
of the graded structures. As a result, the composition-dependent gradation can
produce a broad resonant plasmon band in the optical region, resulting in a
large enhancement of the optical nonlinearity and hence a large figure of
merit.

17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an