Anomalous optical saturation of low-energy Dirac states in graphene and its implication for nonlinear optics
Journal article, 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.

graphene

nonlinear optics

optical saturation

kerr

Author

Behrooz Semnani

Chalmers, Physics

Roland Jago

Chalmers, Physics, Condensed Matter Theory

Safieddin Safavi-Naein

University of Waterloo

Hamed Majedi

University of Waterloo

Perimeter Institute for Theoretical Physics

Ermin Malic

Chalmers, Physics, Condensed Matter Theory

Philippe Tassin

Chalmers, Physics, Condensed Matter Theory

2D Materials

2053-1583 (eISSN)

Vol. 6 3 031003

Subject Categories

Atom and Molecular Physics and Optics

Other Physics Topics

Condensed Matter Physics

DOI

10.1088/2053-1583/ab1dea

More information

Latest update

8/13/2019