Mechanism of High-Order Harmonic Generation from Periodic Potentials

TL;DR

This paper introduces a quasi-classical -space model to understand high-order harmonic generation in solids, accurately predicting spectral features, emission timing, and enabling band structure reconstruction and control of HHG trajectories.

Contribution

It presents a novel -space quasi-classical model that explains HHG in periodic potentials and aligns well with quantum simulations, offering new insights and control methods.

Findings

The model accurately reproduces HHG spectral plateau structures.

It predicts the cutoff energy dependence on laser amplitude.

The emission timing of HHG matches quantum TDSE results.

Abstract

We study numerically the Bloch electron wave-packet dynamics in periodic potentials to simulate laser-solid interactions. We introduce a quasi-classical model in the \emph{k} space combined with the energy band structure to understand the high-order harmonic generation (HHG) process occurring in a subcycle timescale. This model interprets the multiple plateau structure in HHG spectra well and the linear dependence of cutoff energies on the amplitude of vector potential of the laser fields. It also predicts the emission time of HHG, which agrees well with the results by solving the time-dependent Schr\"{o}dinger equation (TDSE). It provides a scheme to reconstruct the energy dispersion relations in Brillouin zone and to control the trajectories of HHG by varying the shape of laser pulses. This model is instructive for experimental measurements.