Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonlinear optical response in gapped graphene   We present a formulation for the nonlinear optical response in gapped
graphene, where the low-energy single-particle spectrum is modeled by massive
Dirac theory. As a representative example of the formulation presented here, we
obtain closed form formula for the third harmonic generation (THG) in gapped
graphene. It turns out that the covariant form of the low-energy theory gives
rise to a peculiar logarithmic singularities in the nonlinear optical spectra.
The universal functional dependence of the response function on dimension-less
quantities indicates that the optical nonlinearity can be largely enhanced by
tuning the gap to smaller values.

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The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin