Characterizing Anomalous High-Harmonic Generation in Solids

TL;DR

This paper develops an ab-initio method to analyze anomalous high-harmonic generation in solids, revealing key characteristics that distinguish it from other harmonic sources and enabling experimental identification and control.

Contribution

It introduces a rigorous ab-initio approach to characterize anomalous HHG in solids, providing insights into its mechanisms and signatures.

Findings

Anomalous HHG increases with laser wavelength.

Pronounced minima occur at specific intensities or wavelengths.

Emission time profiles change drastically near minima.

Abstract

Anomalous high-harmonic generation (HHG) arises in certain solids when irradiated by an intense laser field, as the result of a nonlinear perpendicular current akin to a Hall current. Here, we theoretically characterize the anomalous HHG mechanism, via development of an ab-initio methodology for strong-field laser-solid interaction that allows a rigorous decomposition of the total current. We identify two key characteristics of the anomalous harmonic yields: an overall increase with laser wavelength; and pronounced minima at certain intensities or wavelengths around which the emission time profiles drastically change. Such signatures can be exploited to disentangle the anomalous harmonics from the competing interband harmonics, and thus pave way for the experimental identification and time-domain control of pure anomalous harmonics.