McDonald C R, Vampa G, Corkum P B, Brabec T
Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada.
Phys Rev Lett. 2017 Apr 28;118(17):173601. doi: 10.1103/PhysRevLett.118.173601. Epub 2017 Apr 24.
Experiments on intense laser driven dielectrics have revealed population transfer to the conduction band to be oscillatory in time. This is in stark contrast to ionization in semiconductors and is currently unexplained. Current ionization theories neglect coupling between the valence and conduction band and therewith, the dynamic Stark shift. Our single-particle analysis identifies this as a potential reason for the different ionization behavior. The dynamic Stark shift increases the band gap with increasing laser intensities, thus suppressing ionization to an extent where virtual population oscillations become dominant. The dynamic Stark shift plays a role dominantly in dielectrics which, due to the larger band gap, can be exposed to significantly higher laser intensities.
