Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonlinear coupled-mode theory for periodic plasmonic waveguides and
  metamaterials with loss and gain   We derive general coupled-mode equations describing the nonlinear interaction
of electromagnetic modes in media with loss and gain. Our approach is
rigorously based on the Lorentz reciprocity theorem, and it can be applied to a
broad range of metal-dielectric photonic structures, including plasmonic
waveguides and metamaterials. We verify that our general results agree with the
previous analysis of particular cases, and predict novel effects on self- and
cross-phase modulation in multi-layer nonlinear fishnet metamaterials.

23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph