Improving coherent contrast of petawatt laser pulses.

We report on an experimental study of the "coherent" contrast feature that frequently appears in petawatt(PW)-class laser pulses as an exponentially-rising pedestal within a few tens of picoseconds of the compressed pulse. We show that scattering from the diffraction gratings in the stretcher is the principal source of this feature. Replacing the gratings by new, higher-quality components resulted in an order-of-magnitude reduction in the intensity of the pedestal.

[1]  H. Schonnagel,et al.  Double chirped-pulse-amplification laser: a way to clean pulses temporally. , 2005, Optics letters.

[2]  Marco Galimberti,et al.  The Vulcan 10 PW project , 2010 .

[3]  Jens Limpert,et al.  Decrease of pulse-contrast in nonlinear chirped-pulse amplification systems due to high-frequency spectral phase ripples. , 2008, Optics express.

[4]  On the temporal contrast of high intensity femtosecond laser pulses , 2005 .

[5]  Mikhail Kalashnikov,et al.  Limits of the temporal contrast for CPA lasers with beams of high aperture , 2009, Ultrafast Nonlinear Optics.

[6]  Anders Persson,et al.  Enhanced proton beams from ultrathin targets driven by high contrast laser pulses , 2006 .

[7]  K. Osvay,et al.  High-power Ti:Sapphire lasers: Temporal contrast and spectral narrowing , 2007 .

[8]  Olivier Albert,et al.  10(-10) temporal contrast for femtosecond ultraintense lasers by cross-polarized wave generation. , 2005, Optics letters.

[9]  G. Mourou,et al.  Generation and measurement of >108 intensity contrast ratio in a relativistic kHz chirped-pulse amplified laser , 2005 .

[10]  F. Salin,et al.  Influence of optical quality on chirped-pulse amplification: characterization of a 150-nm-bandwidth stretcher , 1999 .

[11]  Gerard Mourou,et al.  Compression of amplified chirped optical pulses , 1985 .

[12]  Patrick Audebert,et al.  Double plasma mirror for ultrahigh temporal contrast ultraintense laser pulses. , 2007, Optics letters.

[13]  R. Dändliker,et al.  Method for measurement the shape asymmetry of picosecond light pulses , 1968 .

[14]  Jake Bromage,et al.  Impact of high-frequency spectral phase modulation on the temporal profile of short optical pulses. , 2008, Optics express.