High harmonic generation from periodic potentials driven by few-cycle laser pulses

TL;DR

This study models high harmonic generation in solids driven by few-cycle laser pulses using numerical solutions of the time-dependent Schrödinger equation, revealing a two-plateau structure with cutoff energies scaling linearly with field strength and sensitivity to carrier envelope phase.

Contribution

It introduces a numerical approach using B-spline basis sets to simulate HHG in solids, capturing detailed band structure effects and recollision dynamics.

Findings

Harmonic spectra show a two-plateau structure with linear cutoff scaling.

HHG cutoff energy is sensitive to carrier envelope phase.

Results align with recent experimental recollision models.

Abstract

We investigate the high harmonic generation (HHG) from solids by simulating the dynamics of a single active electron in periodic potentials. The corresponding time-dependent Schr\"odinger equations (TDSE) are solved numerically by using B-spline basis sets in coordinate space. The energy band structure and wave vectors can be directly retrived from the eigenfunctions. The harmonic spectra obtained agree well with the results simulated by TDSE in $k$ space using Bloch states and show a two-plateau structure. Both of the cutoff energies of the two plateaus in the harmonic spectrum scale linearly with the field strength. We also study HHG driven by intense few-cycle laser pulses and find that the cutoff energy of the harmonic spectrum is as sensitive to the changes of the carrier envelope phase, as to HHG from gas samples, which suggests recollision pictures in HHG as found by recent experiments (Nature {\bf 522}, 462 (2015)).