High harmonic generation in AlN due to out-of-surface electron orbitals

Abstract

© 2021 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited.High harmonic generation in solids is commonly considered as a bulk process. However, there is a controversy whether the experimentally observed effects can in their entirety be described by a pure bulk model. Our results based on beam propagation and spectral characteristics provide a clear signature of the importance of surface effects on the origin of the harmonic generation in solids. Computations performed with a time-dependent density-functional approach corroborate the experimental measurements.European Metrology Programme for Innovation and Research (CC4C); Ministerio de Economía y Competitividad (FIS2017-85526-R); Horizon 2020 Framework Programme (856415). The authors thank Erin Young for growing and characterizing the AlN samples.Postprint (published version