We demonstrate an all-optical approach for precise characterization of attosecond extreme ultraviolet pulses. An isolated attosecond pulse is produced from high-order harmonics using an intense driving pulse with a proper gating technique. When a weak field is synchronized with the driver, it perturbs the harmonics generation process via altering the accumulated phase of the electron trajectories. The perturbed harmonic spectrum can be formulated as a convolution of the unperturbed dipole and a phase gate, implying the validity of complete reconstruction of isolated attosecond pulses using a conventional frequency-resolved optical gating method. This in situ measurement avoids the central momentum approximation assumed in the widely used attosecond streaking measurement, providing a simple and reliable metrology for an isolated attosecond pulse.

中文翻译：

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全光频率分辨光学选通，用于孤立的阿秒脉冲重建

我们演示了用于精确表征阿秒极端紫外线脉冲的全光学方法。使用适当的选通技术，使用强驱动脉冲，由高次谐波产生一个孤立的阿秒脉冲。当弱磁场与驱动器同步时，它会通过改变电子轨迹的累积相位来扰动谐波的产生过程。可以将扰动的谐波频谱公式化为不受扰动的偶极子和相位门的卷积，这暗示了使用常规的频率分辨光学选通方法完全重建孤立的阿秒脉冲的有效性。这原位 测量避免了广泛使用的阿秒条纹测量中假定的中心动量近似值，从而为隔离的阿秒脉冲提供了简单可靠的度量。