Impact of the electronic band structure in high-harmonic generation spectra of solids

TL;DR

This paper presents an analytic model and first-principles simulations to understand how the electronic band structure influences high-harmonic generation in solids, revealing anisotropic spectra and guiding optimization.

Contribution

The study introduces a new analytic model for HHG in solids validated by first-principles simulations, linking band structure to emission characteristics and polarization control.

Findings

HHG spectra are highly anisotropic and polarization-dependent.

Harmonic yield increases with heavier atoms and potential inhomogeneity.

Cutoff photon energy is independent of driver wavelength.

Abstract

An accurate analytic model describing high-harmonic generation (HHG) in solids is derived. Extensive first-principles simulations within a time-dependent density-functional framework corroborate the conclusions of the model. Our results reveal that: (i) the emitted HHG spectra are highly anisotropic and laser-polarization dependent even for cubic crystals, (ii) the harmonic emission is enhanced by the inhomogeneity of the electron-nuclei potential, the yield is increased for heavier atoms, and (iii) the cutoff photon energy is driver-wavelength independent. Moreover, we show that it is possible to predict the laser polarization for optimal HHG in bulk crystals solely from the knowledge of their electronic band structure. Our results pave the way to better control and optimize HHG in solids by engineering their band structure.