Interband transition-pathway control of high-order harmonics in MgO driven by combined pulses
Phys. Rev. A 113, 063527 – Published 23 June, 2026
DOI: https://doi.org/10.1103/yk8f-499z
Abstract
Based on the multiband strong-field approximation model, we perform a pathway-resolved analysis of high-order harmonic generation in bulk MgO crystals under monochromatic infrared laser and combined pulses. The results show that under the driving of monochromatic infrared pulse, due to the large energy gap between the second conduction band and the valence band of MgO crystal, it is difficult for electrons in the valence band to directly transition to the second conduction band, so the transition pathway with strong harmonic radiation intensity is the pathway containing electrons first transitioning from the valence band to the first conduction band. After adding the ultraviolet high-frequency field, the probability of electron direct transition to the second conduction band is significantly enhanced, and the harmonic radiation intensity of the transition pathway containing electrons first transitioning from the valence band to the second conduction band is significantly improved. In addition, compared with the monochromatic case, we observed a large energy range of harmonic enhancement under the combined pulse drive. Through further analysis, we reveal the main transition pathway sources of the harmonic enhancement region. By adjusting the time delay between the combined pulses and the wavelength of the high-frequency field, both the enhancement region and the spectral peak structure can be effectively controlled. This study demonstrates a pathway-resolved control strategy for harmonic enhancement and highlight its potential for probing and manipulating ultrafast electron dynamics in solids.
