论文部分内容阅读
时间相干性是外种子型自由电子激光(FEL)对于自发辐射自放大(SASE)FEE具有的重要优势之一。利用自制的迈克尔逊干涉仪测量了600 nm(二次谐波)和400 nm(三次偕波)高增益谐波放大(HGHG)FEL的时间相干性,分析不同延迟时间处的干涉图样条纹可见度,得到了600 nm和400 nm HGHG自由电子激光的相干长度,分别为119±6.7 fs和112±16.9 fs。通过与光谱测量和理论计算结果进行比较,进一步验证了实验测量的准确性。结果表明HGHG自由电子激光继承了种子激光的相干性特点,这与理论预测结果相一致。
Temporal coherence is one of the important advantages of extrinsic free-electron lasers (FEL) for spontaneous emission self-amplifying (SASE) FEE. The self-made Michelson interferometer was used to measure the temporal coherence of high gain harmonic amplification (HGHG) of 600 nm (second harmonic) and 400 nm (third harmonic generation), and the interference pattern fringe visibility was analyzed at different delay times. The coherence lengths of HGHG free-electron lasers at 600 nm and 400 nm were obtained, which were 119 ± 6.7 fs and 112 ± 16.9 fs, respectively. Compared with the results of spectral measurement and theoretical calculation, the accuracy of experimental measurement is further verified. The results show that HGHG free electron laser inherits the coherence characteristics of seed laser, which is consistent with the theoretical prediction.