Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical pulse propagation with minimal approximations   Propagation equations for optical pulses are needed to assist in describing
applications in ever more extreme situations -- including those in
metamaterials with linear and nonlinear magnetic responses. Here I show how to
derive a single first order propagation equation using a minimum of
approximations and a straightforward "factorization" mathematical scheme. The
approach generates exact coupled bi-directional equations, after which it is
clear that the description can be reduced to a single uni-directional first
order wave equation by means of a simple "slow evolution" approximation, where
the optical pulse changes little over the distance of one wavelength. It also
also allows a direct term-to-term comparison of an exact bi-directional theory
with the approximate uni-directional theory.

1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin