Anomalous optical saturation of low-energy Dirac states in graphene and its implication for nonlinear optics
Artikel i vetenskaplig tidskrift, 2019

We reveal that optical saturation of the low-energy states takes place in graphene for arbitrarily weak electromagnetic fields. This effect originates from the diverging field-induced interband coupling at the Dirac point. Using semiconductor Bloch equations to model the electronic dynamics of graphene, we argue that the charge carriers undergo ultrafast Rabi oscillations leading to the anomalous saturation effect. The theory is complemented by a many-body study of the carrier relaxations dynamics in graphene. It will be demonstrated that the carrier relaxation dynamics is slow around the Dirac point, which in turn leads to a more pronounced saturation. The implications of this effect for the nonlinear optics of graphene are then discussed. Our analysis shows that the conventional perturbative treatment of the nonlinear optics, i.e. expanding the polarization field in a Taylor series of the electric field, is problematic for graphene, in particular at small Fermi levels and large field amplitudes.


nonlinear optics

optical saturation



Behrooz Semnani

Chalmers, Fysik

Roland Jago

Chalmers, Fysik, Kondenserade materiens teori

Safieddin Safavi-Naein

University of Waterloo

Hamed Majedi

University of Waterloo

Perimeter Institute for Theoretical Physics

Ermin Malic

Chalmers, Fysik, Kondenserade materiens teori

Philippe Tassin

Chalmers, Fysik, Kondenserade materiens teori

2D Materials

2053-1583 (eISSN)

Vol. 6 3 031003


Atom- och molekylfysik och optik

Annan fysik

Den kondenserade materiens fysik



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