Nonlinear and anisotropic polarization rotation in two dimensional Dirac materials

TL;DR

This paper predicts nonlinear optical polarization rotation effects in 2D Dirac materials like graphene and borophene, driven by photo-excited carriers creating measurable Kerr and Faraday rotation signatures.

Contribution

It introduces the concept of nonlinear polarization rotation in 2D Dirac systems due to steady-state photo-excitation, a novel prediction for these materials.

Findings

Finite transverse optical conductivity $\sigma_{xy}(\omega)$ identified

Signatures in Kerr and Faraday rotation predicted

Nonlinear steady state of photo-excited carriers established

Abstract

We predict nonlinear optical polarization rotation in two dimensional massless Dirac systems including graphene and 8-$Pmmn$ borophene. When illuminated, a continuous wave optical field leads to a nonlinear steady state of photo-excited carriers in the medium. The photo-excited population inversion and the inter-band coherence gives rise to a finite transverse optical conductivity, $\sigma_{xy} (\omega)$. This in turn leads to definitive signatures in associated Kerr and Faraday polarization rotation, which are measurable in a realistic experimental scenario.