Experimental research and application of pulse clean technique based on cross polarized wave generation
基于交叉偏振波产生的脉冲净化技术研究与应用

Cross polarized wave (XPW) generation technique is used to improve the contrast of the output pulses from a 800 nm Ti: sapphire femtosecond (fs) laser. The measured temporal contrast of the cleaned pulse is 1011 (limited by the dynamic range of the third-order auto-correlator), which is 3 orders of magnitude higher than the temporal contrast ratio of the initial pulse. The efficiency of XPW is 22%. And the bandwidth of the cleaned pulse is broadened after the XPW nonlinear process. Through the dispersion compensation using double chirped mirrors and fused silica plate, the 25 fs pulse duration is achieved. With the cleaned pulse used as the seed of a TW-level Ti: sapphire chirped-pulse amplification laser system, the 250 mJ/50 fs pulses corresponding to 5 TW peak power are obtained. And the 1011 temporal contrast is demonstrated on the time scale of hundreds of picoseconds before the main femtosecond pulse.