A temporal model for quasi-phase matching in high-order harmonic generation

TL;DR

This paper introduces a one-dimensional temporal model for quasi-phase matching in high-order harmonic generation, analyzing ultrafast plasma dynamics to optimize harmonic output during laser pulses.

Contribution

It presents a novel temporal model for QPM in HHG that accounts for complex plasma dynamics, aiding in optimizing harmonic generation.

Findings

Maximum harmonic pulse energy occurs at the leading edge of the laser pulse.

Identifying a single optimal QPM period is complex due to plasma dynamics.

The model helps in understanding ultrafast plasma effects on HHG.

Abstract

We present a model for quasi-phase matching (QPM) in high-order harmonic generation (HHG). Using a one-dimensional description, we analyze the time-dependent, ultrafast wave-vector balance to calculate the on-axis harmonic output versus time, from which we obtain the output pulse energy. Considering, as an example, periodically patterned argon gas, as may be provided with a grid in a cluster jet, we calculate the harmonic output during different time intervals within the drive laser pulse duration. We find that identifying a suitable single spatial period is not straightforward due to the complex and ultrafast plasma dynamics that underlies HHG at increased intensities. The maximum on-axis harmonic pulse energy is obtained when choosing the QPM period to phase match HHG at the leading edge of the drive laser pulse.