High-harmonic generation in alpha-quartz by the electron-hole recombination

TL;DR

This study uses time-dependent density functional theory to analyze high-harmonic generation in alpha-quartz, revealing the role of electron-hole recombination and producing attosecond pulse trains.

Contribution

It demonstrates the significance of electron-hole recombination in HHG in alpha-quartz and provides detailed numerical analysis of the process.

Findings

HHG cutoff limited at 19th harmonic (30 eV)

HHG efficiency depends on laser intensity and hole density

200-attosecond pulse train generated from HHG

Abstract

A calculation of the high-harmonic generation (HHG) in $\alpha$-quartz using the time-dependent density functional theory is reported. The inter-band process is attributed to the dominant in HHG above the band gap. The photon energy is set to 1.55 eV, and the cutoff energy of the plateau region is found to be limited at the 19th harmonic (30 eV). The dependence of the HHG efficiency at the cutoff energy region on laser intensity is consistent with that of the hole density in the lowest-lying valence band. Numerical results indicate that electron-hole recombination plays a crucial role in HHG in $\alpha$-quartz. It is found that a 200 attosecond pulse train is produced using HHG around the plateau cutoff energy.