Eur. Phys. J. D 55, 407-414 (2009)
https://doi.org/10.1140/epjd/e2009-00187-4

Relativistic high harmonics and (sub-)attosecond pulses: relativistic spikes and relativistic mirror

Institut für Theoretische Physik I, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany

Corresponding author: ^a pukhov@thphy.uni-duesseldorf.de

Received: 17 November 2008
Revised: 29 April 2009
Published online: 23 June 2009

Abstract

Using particle-in-cell simulations, we study high harmonic generation from overdense plasmas in the relativistic regime. Different incidence angles as well as different laser polarizations are considered and scalings are recovered. It is shown that the theory of relativistic spikes and the BGP power-law spectra [Phys. Rev. E 74, 046404 (2006)] describes well the normal incidence and s-polarized obliquely incident laser pulses. In the case of p-polarized laser pulses, exceptions from the BGP theory can appear when the quasi-static vector potential build-up at the plasma boundary becomes equal to that of the laser. In this case, the spectrum flattens significantly and has a lower cutoff.