Ultrashort laser pulse driven currents in conductors: physical mechanisms and time scales

TL;DR

This paper investigates how ultrashort laser pulses induce currents in conductors, analyzing the physical mechanisms and time scales involved, including charge wave packets and oscillations related to the laser field.

Contribution

It provides a detailed analysis of the physical mechanisms and time scales of laser-driven currents in conductors, considering various electron energies and interaction parameters.

Findings

Charge wave packets travel near the initial band velocity.

Oscillations occur at the laser frequency.

Localized ponderomotive potential causes slow current oscillations.

Abstract

The response of conduction band electrons to a local, pulse-like external excitation is investigated. The charge density wave packets that emerge as a consequence of the excitation leave the interaction region with a speed close to the initial state's band velocity, but there are also oscillations with essentially the same frequency as that of the laser field. As a good estimation, the excitation can also be considered as a localized, time-dependent ponderomotive potential, leading to slowly varying current oscillations. The role of all these effects are investigated for different electron energies, carrier frequencies and sizes of the interaction area.