基于交叉偏振波产生的脉冲净化技术研究与应用

本文利用交叉偏振波产生技术(XPW)对800 nm波段钛宝石飞秒激光器输出的激光脉冲进行时域净化, 提高脉冲时域对比度, 并测量验证了10¹¹对比度的脉冲, 达到测量仪器的动态范围极限, 比初始脉冲时域对比度有三个量级的提高, XPW的效率为22%. 同时发现净化后脉冲光谱宽度也得到一定展宽, 进一步利用啁啾镜对和补偿片对净化后的脉冲进行色散补偿, 得到25 fs脉宽的脉冲. 利用该净化后的激光脉冲作为种子注入已有的太瓦级钛宝石啁啾脉冲放大系统中, 在输出脉冲能量250 mJ, 宽度50 fs, 对应峰值功率5 TW的情况下, 在主脉冲前100 ps以外的范围内测量验证了10¹¹的脉冲对比度.

Experimental research and application of pulse clean technique based on cross polarized wave generation

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.