Third-order terahertz optical response of graphene in the presence of Rabi Oscillations

TL;DR

This paper investigates the nonlinear terahertz optical response of graphene nanoribbons, revealing the presence of Rabi oscillations, harmonic generation, and power spectrum decay through quantum modeling beyond classical approaches.

Contribution

It introduces a quantum model for graphene's THz response including Rabi oscillations, predicting harmonic generation and spectral features not captured by semiclassical models.

Findings

Prediction of odd and even harmonics in the THz response

Observation of continuum oscillations in the power spectrum

Rapid decay of power harmonics over time

Abstract

Graphene has been shown to exhibit a nonlinear response due to its unique band structure. In this paper, we study the terahertz (THz) response metallic armchair graphene nanoribbons, specifically current density and Rabi oscillations beyond the semiclassical Boltzman model. We performed quantum mathematical modeling by first finding a solution to the unperturbed Hamiltonian for a single Fermion in the dipole gauge and then applying a polarized, THz electrical field. After writing the solution in terms of the four eigenstates of the Dirac system, we numerically calculated the $x$ and $y$ components of the induced current density resulting from applying the terahertz electrical field. Due to the inclusion of the Rabi Oscillation in our calculation of the optical response, we predict both odd and even harmonics, as well as continuum oscillations of the power density spectrum in the THz regime. Lastly, we show a rapid decay of the power harmonics.