Propagation time and nondipole contributions to intraband high-harmonic generation

TL;DR

This paper investigates how propagation time and nondipole effects influence intraband high-harmonic generation, revealing spectral features like even harmonics and potential experimental measurement methods.

Contribution

It introduces a semiclassical model that accounts for propagation time and nondipole effects in intraband HHG, highlighting their impact on spectral features.

Findings

Propagation time affects harmonic spectra.

Nondipole corrections enable observation of even harmonics.

Spectral features depend on system symmetry and geometry.

Abstract

Applying the semiclassical model, we identify two connected effects in intraband high-harmonic generation (HHG): (1) propagation time from the point of emission at the source to the point of detection, (2) beyond-electric-dipole corrections to the light-matter interaction. These effects inherit information regarding the dispersion and cause specific features in the spectra including even-ordered harmonics in systems with space- and time-inversion symmetry. They can for certain experimental geometries be measured free of the dipole background.