High dynamic range temporal characterization of femtosecond Ti:sapphire oscillators

Summary form only given. The main problem limiting today the field of application of multi-terawatts femtosecond lasers in laser-matter experiments is the level of amplified spontaneous emission (ASE) which remains far above the ionization threshold of most materials. Some techniques based on second harmonic generation (SHG) autocorrelation have been developed, but the dynamic is limited to about 8 orders of magnitude and moreover such measurement do not provide any informations on the asymmetry of the pulse shape and do not differentiate the leading and the falling edge. To overpass this problem we have built a high dynamic range third order correlator. As the energy per pulse is small, we added silica lenses in the arms to focus the beams in the non linear crystals (SHG and sum frequency generation (SFG)).