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Grabielle, S.

Paper Title Page
WEPPH001 Femtosecond CPA-based Laser Research & Development Program for Photoinjectors  
 
  • D. Garzella, S. Grabielle, J-F. Hergott, Ph. Hollander, D. Jourdain, F. Lepetit, M. Perdrix, O. Tcherbakoff, O. B. Gobert
    CEA, Gif-sur-Yvette
  • T. Oksenhendler
    FASTLITE, Palaiseau
  • G. D. Rovera
    LNE-SYRTE, Paris
 
  High Brightness, electron Linac-based light sources call for synergy with conventional high energy laser sources. Indeed, photoinjectors R&D needs lasers R&D. The Ti:S lasers based on Chirped Pulse Amplification (CPA) techniques can supply the requested light features for operating with such accelerator systems, provided that one can shape and control the laser pulses in the temporal and spatial domain. In the EUROFEL European program framework, the investigations performed by the LUCA/PLFA team at the Saclay Laser Interaction Center are twofold : - Temporal and spatial shaping of fs UV laser pulses. Temporal beam shaping is performed through an amplitude and phase modulation in the pulse spectral domain by means of an active programmable system. Transverse pulse shaping is achieved with a passive optical system based on aspheric optics. A combination of both techniques allows one to obtain "beer can" shaped photoelectron bunches easily. -Investigations in laser/LINAC synchronization and timing distribution. Optical experimental techniques are used to measure the drift and the jitter at the output laser system whose oscillator repetition rate is locked on a Rb atomic clock. In the present paper the major numerical studies and experimental results are presented. Further considerations on the benefits and the limits brought by these experimental techniques will be discussed.  
WEPPH002 Longitudinal and Spatial shaping of UltraViolet Femtosecond laser pulses: Theoretical Investigations and Experimental Results  
 
  • D. Garzella, S. Grabielle, J-F. Hergott, Ph. Hollander, D. Jourdain, F. Lepetit, M. Perdrix, O. Tcherbakoff, O. B. Gobert
    CEA, Gif-sur-Yvette
  • T. Oksenhendler
    FASTLITE, Palaiseau
 
  The search for minimized emittance high charge electron bunches calls for increased efforts in controlling the temporal and spatial features of photoinjector drive lasers. In the EUROFEL framework, the LUCA/PLFA team in Saclay (SLIC) is investigating the longitudinal and transverse shaping of ultrashort laser pulses. The main goal is to obtain properly shaped UV (@266 nm) ps laser pulses. Temporal pulse shaping is performed through amplitude and phase modulation in the spectral domain with an acousto-optic programmable dispersive filter (Dazzler). Square and parabolic shapes are achieved either by modulating an IR laser pulse (@800 nm) before UV up-conversion, or by a direct manipulation of the UV pulse. Analogies and differences between the two procedures are here underlined through theoretical and experimental studies. Transverse shaping is obtained by using a passive optical system based on aspheric optics, leading to a homogeneous flat-top transverse distribution. The major results on a UV pulse are shown. Moreover, preliminary experimental studies, introducing the use of a deformable mirror and the effects of spatial phase modulation on the laser pulse are also presented here, together with a theoretical analysis. Combined longitudinal and transverse shaping allows us to obtain "beer can" shaped laser pulses easily, and thus photoelectron bunches of the same shape.