Nowadays, the high-order harmonic generation process is an extended useful tool for the study of femtosecond dynamics. Nevertheless, there are still many doubts regarding the electron behavior inside different types of mediums.
Recent studies in solid targets have revealed new scenarios with extraordinary electronic dynamics compared with atoms or molecules. The process in solids can be explain through a semiclassical point of view using the electron trajectory from the excitation until the recombination with its hole in real space; the so-called perfect recollisions. However, recent studies have confirmed that part of the high-order harmonic emissions comes from trajectories where the electron and hole do not overlap in real space; the so-called imperfect recollisions.
In this work, we demonstrate the existence of imperfect recollisions when the medium is a single-layer graphene, and the driving laser pulse is linearly polarized. Graphene, compared to other solids, presents a singular structure band with points where the valence and conduction band are in contact. Our study has a great relevance because until this moment there were studies only with finite-gap solids and huge Berry curvature or using a driving field with elliptical polarization. We truly believe that this work takes a new step in the full understanding of the ultrafast dynamics driven by intense laser pulses in solids.
More information at:
Boyero-García, Roberto, Ana García-Cabrera, Oscar Zurrón-Cifuentes, Carlos Hernández-García, y Luis Plaja. «Non-classical high harmonic generation in graphene driven by linearly-polarized laser pulses». Opt. Express 30, n.o 9 (abril de 2022): 15546-55. https://doi.org/10.1364/OE.452201.