Coherent buildup of high harmonic radiation: the classical perspective

TL;DR

This paper introduces a classical model for high harmonic generation that accurately predicts laser pulse behavior and harmonic cutoff extension during propagation, aligning well with quantum models and revealing underlying mechanisms.

Contribution

The paper presents a classical approach to model high harmonic generation, providing insights into propagation effects and cutoff extension that complement quantum descriptions.

Findings

Classical model matches quantum results for blueshift and intensity reduction.

Propagation effects significantly extend the high-harmonic cutoff.

Phase-space analysis uncovers the mechanism behind cutoff extension.

Abstract

We present a classical model for high harmonic generation during the propagation of an intense laser pulse through an atomic gas. Numerical simulations of the model show excellent quantitative agreement with the corresponding quantum model for the blueshift and intensity reduction of the propagating laser pulse over experimentally realistic propagation distances. We observe a significant extension of the high-harmonic cutoff due to propagation effects. Phase-space analysis of our classical model uncovers the mechanism behind this extension.