We demonstrate significant temporal contrast improvement for a petawatt-class Ti:sapphire femtosecond laser by introducing a temporal pulse filter based on a self-diffraction process. A double chirped-pulse-amplification laser system was set up to stretch, amplify and recompress the generated first-order self-diffraction pulse. The maximum energy of 130 μJ has been achieved for one first-order self-diffraction seed pulse. By optimizing the initial chirp value, the spectral bandwidth was slightly broadened for the first-order self-diffraction pulse and the cleaned pulse did not exhibit visible spectral distortions in the air environment. The measurement results for the incident pulse and the recompressed first-order self-diffraction pulse showed that the temporal contrast was improved by seven orders of magnitude, i.e. from ∼105 to ∼1012 at −25 ps before the main pulse. Such a temporal contrast is beneficial for laser-matter interaction experiments with high focused intensity up to 1022 W/cm2.

中文翻译：

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通过自衍射工艺改善拍瓦级钛蓝宝石激光器的时间对比度

我们通过引入基于自衍射过程的时间脉冲滤波器，证明了拍瓦级 Ti:sapphire 飞秒激光器的显着时间对比度改进。建立双啁啾脉冲放大激光系统对产生的一阶自衍射脉冲进行展宽、放大和再压缩。一个一阶自衍射种子脉冲已达到 130 μJ 的最大能量。通过优化初始啁啾值，一阶自衍射脉冲的光谱带宽略微加宽，并且清洁后的脉冲在空气环境中没有表现出可见的光谱失真。入射脉冲和再压缩的一阶自衍射脉冲的测量结果表明，时间对比度提高了七个数量级，即 在主脉冲前 -25 ps 从 ~105 到 ~1012。这种时间对比度对于具有高达 1022 W/cm2 的高聚焦强​​度的激光-物质相互作用实验是有益的。