We experimentally explore the generation of pre-pulses by post-pulses, created through internal reflection in the optical components, by the nonlinear process associated with the B-integral in the laser chain of the petawatt (PW) facility J-KAREN-P. At a large time delay between the main and the post-pulses, we have found that the pre-pulses are not generated from their counterpart post-pulses at an identical time difference before the main pulse, and the temporal shapes of the pre-pulses are greatly distorted asymmetrically. We have also observed that the peak intensities of the pre-pulses are drastically suppressed compared to the expected value at a small time delay. We briefly describe the origins of the pre-pulses generated by the post-pulses and demonstrate the removal of the pre-pulses by switching to optical components with a small wedge angle at our PW laser facility.

中文翻译：

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在PB激光设备中对前脉冲与后脉冲的时间对比进行实验研究。

我们实验研究了通过与皮瓦（PW）设施J-KAREN-P的激光链中B积分相关的非线性过程，通过光学组件内部反射产生的后脉冲产生的前脉冲。在主脉冲和后脉冲之间有较大的时间延迟时，我们发现在主脉冲之前的相同时间差处，预脉冲不是由其对应的后脉冲产生的，并且前脉冲的时间形状被极大地不对称扭曲。我们还观察到，与预想的值相比，预脉冲的峰值强度在较小的时间延迟下得到了显着抑制。