In this section
@article{Broughton:2026:2515-7647/ae7f5a,
author = {Broughton, JJ and Allegre, H and Marangos, JP and Tisch, J and Matthews, M},
doi = {2515-7647/ae7f5a},
journal = {Journal of Physics: Photonics},
title = {Beyond the plateau: A phenomenological review of the cutoff in solid high harmonic generation},
url = {http://dx.doi.org/10.1088/2515-7647/ae7f5a},
year = {2026}
}
TY - JOUR
AB - <jats:title>Abstract</jats:title> <jats:p>Solid high-harmonic generation (sHHG) has emerged as a powerful platform for generating coherent ultraviolet and extreme-ultraviolet radiation and for probing ultrafast electron dynamics in condensed matter. Central to both applications is the high-harmonic cutoff energy, which defines the maximum photon energy attainable and encodes information on the interplay between strong-field driving conditions and the electronic structure of the generating medium. Unlike in gases, where the cutoff follows a well-established ponderomotive scaling, the solid-state cutoff arises from a complex combination of band structure, multiband coupling, carrier dynamics, and propagation effects, and no universal scaling law has yet been established. In this Topical Review, we synthesise the current theoretical and experimental understanding of the cutoff in sHHG, spanning microscopic electron-hole dynamics, intraband and interband emission mechanisms, and their manifestation in plateau formation and spectral extension. We examine how the cutoff scales with driving field strength, wavelength, polarisation, and crystal orientation, and discuss the role of multiband trajectories, Bloch oscillations, and electron dynamics. We further review how macroscopic factors, including absorption, phase matching, propagation, and laser-induced damage, constrain the observable cutoff, often limiting spectral extension even when higher-energy emission is generated microscopically. Strategies for extending the cutoff are assessed, including tailored driving fields, nanostructured and metasurface targets, low-dimensional materials, and band-structure engineering via strain, defects, and doping. Finally, we discuss the spectroscopic significance of the cutoff region, highlighting its sensitivity to band dispersion, ultrafast carrier dynamics, and light-induced electronic structure. By consolidating these perspectives, this review c
AU - Broughton,JJ
AU - Allegre,H
AU - Marangos,JP
AU - Tisch,J
AU - Matthews,M
DO - 2515-7647/ae7f5a
PY - 2026///
TI - Beyond the plateau: A phenomenological review of the cutoff in solid high harmonic generation
T2 - Journal of Physics: Photonics
UR - http://dx.doi.org/10.1088/2515-7647/ae7f5a
UR - https://doi.org/10.1088/2515-7647/ae7f5a
ER -