Nonperturbative quasi-classical theory of the nonlinear electrodynamic response of graphene

TL;DR

This paper develops a nonperturbative quasi-classical theory to analyze the nonlinear electrodynamic response of graphene under strong electric fields, revealing effects like optical bistability disappearance and high-power transparency.

Contribution

It introduces an exact kinetic Boltzmann equation approach for graphene's nonlinear response, extending beyond perturbative methods and clarifying high-power optical effects.

Findings

Optical bistability predicted by perturbative theory is not observed in the exact solution.

High-power radiation causes a significant decrease in reflection and absorption, making graphene transparent.

The theory is valid at low frequencies where photon energy is less than twice the Fermi energy.

Abstract

An electromagnetic response of a single graphene layer to a uniform, arbitrarily strong electric field $E(t)$ is calculated by solving the kinetic Boltzmann equation within the relaxation-time approximation. The theory is valid at low (microwave, terahertz, infrared) frequencies satisfying the condition $\hbar\omega\lesssim 2E_F$, where $E_F$ is the Fermi energy. We investigate the saturable absorption and higher harmonics generation effects, as well as the transmission, reflection and absorption of radiation incident on the graphene layer, as a function of the frequency and power of the incident radiation and of the ratio of the radiative to scattering damping rates. We show that the optical bistability effect, predicted in Phys. Rev. B 90, 125425 (2014) on the basis of a perturbative approach, disappears when the problem is solved exactly. We show that, under the action of a high-power radiation ($\gtrsim 100$ kW/cm$^2$) both the reflection and absorption coefficients strongly decrease and the layer becomes transparent.