Petahertz optical response in graphene

TL;DR

This paper explores graphene's ultrafast optical response at petahertz frequencies, revealing how hot carriers influence its nonlinear behavior on sub-100 femtosecond timescales, with implications for future high-speed optoelectronic devices.

Contribution

It provides the first detailed investigation of graphene's instantaneous nonlinear response to petahertz optical fields, emphasizing hot carrier dynamics and their back action.

Findings

Hot carriers significantly affect graphene's optical response within 100 fs.

The nonlinear response depends on interaction time and polarization.

Carrier trajectories are influenced by optical field polarization.

Abstract

The temporal dynamics of charge carriers determines the speed with which electronics can be realized in condensed matter, and their direct manipulation with optical fields promises electronic processing at unprecedented petahertz frequencies, consisting in a million-fold increase from state of the art technology. Graphene is of particular interest for the implementation of petahertz optoelectronics due to its unique transport properties, such as high carrier mobility with near-ballistic transport and exceptionally strong coupling to optical fields. The back action of carriers in response to an optical field is therefore of key importance towards applications. Here we investigate the instantaneous response of graphene to petahertz optical fields and elucidate the role of hot carriers on a sub-100 fs timescale. Measurements of the nonlinear response and its dependence on interaction time and field polarization allow us to identify the back action of hot carriers over timescales that are commensurate with the optical field. An intuitive picture is given for the carrier trajectories in response to the optical-field polarization state. We note that the peculiar interplay between optical fields and charge carriers in graphene may also apply to surface states in topological insulators with similar Dirac cone dispersion relations.