Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Graphene optical nonlinearity: From the third-order to the
  non-perturbative electrodynamic regime   A non-perturbative model for graphene optical nonlinearity is developed for
the study of ultrafast pulse propagation along a monolayer, as in the case of
graphene-comprising nanophotonic integrated waveguides. This graphene `hot
electron' model (GHEM) builds upon earlier work, based on the Fermi-Dirac
framework for 2D semiconductors, which was aimed mainly at steady-state
absorptive response of a monolayer under free-space laser-beam illumination.
Our extension adapts the GHEM to in-plane light-matter interaction along
graphene monolayers under intense ps-pulse excitation that leads to the
carrier-density saturation regime. We first provide a quantitative overview of
the `classic' perturbative third-order nonlinear response and then study the
static and transient response of graphene as a function of the GHEM parameters,
with focus on the monolayer quality and voltage-tunability. These results are
compared to phenomenological models for saturable absorption and nonlinear
refraction, showing good agreement with recent experimental works. In
conclusion, the GHEM unifies the experimentally observed absorptive and
refractive optical nonlinearities in a single multi-parametric framework
therefore enabling the evaluation of the voltage-tunable light-matter
interaction in structures such as diffraction-limited nanophotonic waveguides.
This formalism can be readily employed to THz frequencies, adapted to
multi-channel (e.g. pump-probe) nonlinear effects, or developed to include
carrier and lattice-temperature diffusion to extend its validity threshold.

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The categories of this paper are: math-ph
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The categories of this paper are: q-alg
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The categories of this paper are: bayes-an
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The categories of this paper are: eess
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The categories of this paper are: hep-lat
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-th
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The categories of this paper are: acc-phys
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The categories of this paper are: adap-org
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The categories of this paper are: math
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The categories of this paper are: solv-int
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The categories of this paper are: alg-geom
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The categories of this paper are: chao-dyn
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The categories of this paper are: cs
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The categories of this paper are: gr-qc