Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Beyond the effective mass approximation: predictive theory of the
  nonlinear optical response of conduction electrons   We present an experimental and computational study of the nonlinear optical
response of conduction electrons to intense terahertz (THz) electric field. Our
observations (saturable absorption and an amplitude-dependent group refractive
index) can be understood on the qualitative level as the breakdown of the
effective mass approximation. However, a predictive theoretical description of
the nonlinearity has been missing. We propose a model based on the
semiclassical electron dynamics, a realistic band structure, and the free
electron Drude parameters to accurately calculate the experimental observables
in InSb. Our results open a path to predictive modeling of the
conduction-electron optical nonlinearity in semiconductors, metamaterials, as
well as high-field effects in THz plasmonics.

32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
16
The categories of this paper are: stat