Improving The Contrast Ratio Of High Power Femtosecond Laser By Using Of OPCPA Technique

The contrast ratio, defined as the peak intensity of the main pulse to the intensity of the largest pre-pulse, is a very important parameter of the high intensity femtosecond laser pulse, and which is the bottle in limiting the further using of the femtosecond laser in the fields of the high field physics, high order harmonic generation and laser fusion, etc.The optical parametric chirped pulse amplification (abbreviate to OPCPA) possesses the advantages of the optical parametric amplification (abbreviate to OPA) and the chirped pulse amplification (abbreviate to CPA) together, which includes the characters such as very high gain coefficient, broadband gain bandwidth, weakly thermal effect and high energy conversion coeffient. Adopting the OPCPA is a most potential way to archeve high intensity femtosecond with high contrast after many key techniques to be solved. Nowadays, many high femtosecond with high contrast is archieved by adopting the OPCPA to altenate the regenetive amplifier in traditional CPA lasers.Firstly, the influences of the third order nonlinear Ken effect and the dispersion originated from the mismatch of the grating pairs in the compressed stage on the contrast and the temporal-spatial domain properties of the femtosecond are researched. Secondly, the property of the OPCPA laser operation in the big gain regime is studied. Thirdly, the effects of synchronization jetter between the signal pulse and the pump pulse in the OPCPA system and its traditional solvesion, namely...