Topic/Type: 1.3 High intensity Laser Plasma Interaction, Poster

Effect of chirp and pulse shaping on high harmonic generation from overdense plasmas

Fran?ois Vidal, Xavier Lavocat-Dubuis

Institut national de la recherche scientifique - Centre ?nergie, mat?riaux et t?l?communications, Varennes, Qu?bec, Canada

We present a numerical investigation on the effect of dispersion and temporal shape of ultra intense laser pulses on high harmonic generation from overdense plasmas. When only the group velocity dispersion (GVD) term is present, the pulse temporal shape remains Gaussian and no differences were seen in the harmonic spectra between positive and negative GVD, although significant differences were observed in plasma heating. However, when the third order dispersion (TOD) is present, the pulse shape is no longer symmetric in time and significant differences in harmonics intensity and frequency are observed when GVD changes sign. We show that this effect is essentially linked to the steepness of the leading edge of the pulse envelope. We also show that the longitudinal dynamics of the plasma critical surface plays a crucial role in the efficiency of high harmonic generation.