In this paper, the relation between Van Hove singularities (visible in materials’ band structure) and the spectrum of high harmonics has been demonstrated for silicon irradiated by ultrashort laser pulses of mid-infrared and near-infrared wavelengths.
It has been shown that, using ab-initio modeling, it is possible to predict the spectrum of harmonics for different crystal orientations with respect to the light polarization without the need to use any adjusting parameters. The work was performed in collaboration with Charles University, Prague.
Left: Scheme of harmonic spectroscopy. Right: Effect of sample orientation on the high harmonic emission by light-irradiated silicon. (a) Experimental data. (b) Quantum simulation results obtained using the ab-initio TDDFT method.