Macroscopic aspects of relativistic x-ray assisted high-order harmonic generation

TL;DR

This paper presents a theoretical model for high-order harmonic generation in relativistic regimes, focusing on macroscopic propagation, phase matching, and optimizing laser geometry with x-ray assistance to enhance yield.

Contribution

It introduces a new theoretical framework for relativistic HHG considering macroscopic effects and phase matching with x-ray assistance, which was not previously detailed.

Findings

Phase-matched harmonic emission is possible in relativistic HHG.

Optimized laser geometry enhances HHG yield.

Macroscopic propagation effects are crucial for efficient HHG.

Abstract

A theoretical model is developed describing high-order harmonic generation (HHG) from a gas of multiply-charged ions driven by a laser field of relativistic intensity. Macroscopic propagation of harmonics is investigated in a relativistic HHG setup where the relativistic drift is suppressed by means of x-ray field assistance of the driving laser field. The possibility of phase-matched emission of the harmonics is shown. The laser field geometry is optimized to maximize the HHG yield with the corresponding phase-matching schemes. Crucial issues determining the macroscopic HHG yield are discussed in detail.