Fourier-limited attosecond pulse generation with magnetically pumped high-order harmonic generation

Grupo de Investigación en Aplicaciones del Láser y Fotónica, Departamento de Física Aplicada, Universidad de Salamanca, E-37008, Salamanca, Spain.

^* Corresponding author: rodrigomh@usal.es

Published online: 13 October 2022

Abstract

After more than two decades of attosecond physics, the generation and control of the shortest laser pulses available remains as a complex task. One of the main limitations of reducing the temporal duration of attosecond pulses emitted from high-order harmonic generation (HHG) is the attochirp. In this contribution, we demonstrate that HHG assisted by strong fast oscillating magnetic fields enables the generation of Fourierlimited attosecond pulses in the water window. In short, the magnetic field generates a nanowire-like structure, which transversally confines the electronic wavefunction in the HHG process. We demonstrate that the resulting HHG spectrum extends well beyond the semiclassical cutoff frequency, and most interestingly, it is emitted in the form of few-cycle, Fourier-limited, attosecond pulses.