Phase-matching gating for isolated attosecond pulse generation

TL;DR

This paper explores phase-matching gating in high-harmonic generation to produce isolated attosecond pulses, analyzing how propagation effects and pulse duration influence IAP generation feasibility.

Contribution

It introduces a comprehensive model combining propagation equations with quantum simulations to identify conditions for optimal IAP production.

Findings

IAP production onset correlates with quadratic energy dependence on propagation distance.

Upper fundamental pulse duration limit is set by nonlinear pulse spreading during propagation.

Phase-matching gating effectively isolates attosecond pulses under specific conditions.

Abstract

We investigate the production of an isolated attosecond pulse~(IAP) via the phase-matching gating of high-harmonic generation by intense laser pulses. Our study is based on the integration of the propagation equation for the fundamental and generated fields with nonlinear polarisation found via the numerical solution of the time-dependent Schr\"odinger equation. We study the XUV energy as a function of the propagation distance (or the medium density) and find that the onset of the IAP production corresponds to the change from linear to quadratic dependence of this energy on the propagation distance (or density). Finally, we show that the upper limit of the fundamental pulse duration for which the IAP generation is feasible is defined by the temporal spreading of the fundamental pulse during the propagation. This nonlinear spreading is defined by the difference of the group velocities for the neutral and photoionised medium.