# Nonadiabatic high-order harmonic generation from solids

## TL;DR

This paper numerically investigates nonadiabatic effects in high-order harmonic generation from solids, revealing redshifts, increased spectral widths, and even harmonics in higher plateaus, which could guide future experiments.

## Contribution

It demonstrates the influence of nonadiabatic effects on HHG spectra from solids, highlighting spectral shifts and symmetry breaking in higher plateaus.

## Key findings

- Redshifted HHG spectra in short pulses due to nonadiabatic effects
- Increased FWHMs indicating step-by-step excitation of conduction bands
- Presence of even harmonics in higher plateaus due to symmetry breaking

## Abstract

We studied the multi-plateau high-order harmonic generation (HHG) from solids numerically. It is found that the HHG spectrum in the second or higher plateau is redshifted in short laser pulses due to the nonadiabatic effect. The corresponding FWHMs also increase, suggesting the step-by-step excitation process of higher conduction bands in the HHG process. Even order harmonics in the higher plateaus of HHG are present due to the break of symmetry in the k space. It may stimulate related experimental work.

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Source: https://tomesphere.com/paper/1704.06218