Interaction of graphene monolayer with ultrashort laser pulse

TL;DR

This paper investigates how ultrashort laser pulses interact with graphene, revealing complex electron dynamics, localized conduction band populations, and controllable charge transfer directions based on pulse intensity.

Contribution

It provides a detailed analysis of electron dynamics in graphene under ultrashort pulses, highlighting the wave vector dependence and charge transfer control, which are novel insights.

Findings

Localized high conduction band population near Dirac points

Charge transfer direction reverses with pulse intensity

Electron dynamics are highly irreversible and nonuniform

Abstract

We study the interaction of graphene with ultrashort few femtosecond long optical pulse. For such a short pulse, the electron dynamics is coherent and is described within the tight-binding model of graphene. The interaction of optical pulse with graphene is determined by strong wave vector dependence of the interband dipole matrix elements, which are singular at the Dirac points of graphene. The electron dynamics in optical pulse is highly irreversible with large residual population of the conduction band. The residual conduction band population as a function of the wave vector is nonuniform with a few localized spots of high conduction band population. The spots are located near the Dirac points and the number of spots depends on the pulse intensity. The optical pulse propagating through graphene layer generates finite transferred charge, which, as a function of pulse intensity, changes its sign. At small pulse intensity, the charge is transferred in the direction of the pulse maximum, while at large pulse intensity, the direction of the charge transfer is opposite to the direction of pulse maximum. This property opens unique possibility of controlling the direction of the charge transfer by variation of the pulse intensity.