Ultrafast optical currents in gapped graphene

TL;DR

This paper theoretically investigates how ultrashort optical pulses induce electric currents in gapped graphene, revealing a unique rectification effect due to its broken inversion symmetry and symmetry properties.

Contribution

It demonstrates the generation of transverse rectified currents in gapped graphene under polarized ultrashort pulses, highlighting the inter-band origin of this effect.

Findings

Rectified current is generated perpendicular to the pulse polarization.

Conduction band population distribution is symmetric about the x-axis.

Rectified current arises from inter-band transitions, intra-band contribution is zero.

Abstract

We study theoretically the interaction of ultrashort optical pulses with gapped graphene. Such strong pulse results in finite conduction band population and corresponding electric current both during and after the pulse. Since gapped graphene has broken inversion symmetry, it has an axial symmetry about the $y$-axis but not about the $x$-axis. We show that, in this case, if the linear pulse is polarized along the $x$-axis, the rectified electric current is generated in the $y$ direction. At the same time, the conduction band population distribution in the reciprocal space is symmetric about the $x$-axis. Thus, the rectified current in gapped graphene has inter-band origin, while the intra-band contribution to the rectified current is zero.