Regular Article

The European Physical Journal D

, 68:195

First online:

High-order harmonic generation at high laser intensities beyond the tunnel regime

  • Jose Antonio Pérez-HernándezAffiliated withCentro de Láseres Pulsados (CLPU) Email author 
  • , Marcelo F. CiappinaAffiliated withDepartment of Physics, Auburn University
  • , Maciej LewensteinAffiliated withICFO-Institut de Ciències FotòniquesICREA-Institució Catalana de Recerca i Estudis Avançats
  • , Amelle ZaïrAffiliated withDepartment of Physics, Blackett Laboratory, Imperial College London
  • , Luis RosoAffiliated withCentro de Láseres Pulsados (CLPU)

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We present studies of high-order harmonic generation (HHG) at laser intensities well above saturation. We use driving laser pulses which present a particular electron dynamics in the turn-on stage. Our results predict an increasing on the harmonic yield, after an initial dropping, when the laser intensity is increased. This fact contradicts the general belief of a progressive degradation of the harmonic emission at ultrahigh intensities. We have identified a particular set of trajectories which emerges in the turn-on stage of these singular laser pulses, responsible of the unexpected growth on the harmonic efficiency at this high intensity regime. Our study combines two complementary approaches: classical analysis and full quantum mechanical calculations resulting from the numerical integration of the 3-dimensional time-dependent Schrödinger equation complemented with the time-frequency analysis.