Temporal characterization of a laser pulse is an essential task in many applications. Temporal characterization methods that are currently available support only a limited spectral bandwidth without information on the carrier-envelope phase (CEP) of the laser pulse or require complicated equipment in a vacuum environment. Here we demonstrate that an arbitrary time-dependent laser field can be directly sampled using subcycle tunneling ionization in a gaseous medium or in air. The subcycle ionization is used as a fast temporal gate for the direct sampling of the laser field. This unique approach enables the complete temporal characterization of the laser field, including its CEP, for a broad spectral range in ambient air, providing a universal tool for the precise measurement of the laser field.

中文翻译：

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直接采样空气中的光波

在许多应用中，激光脉冲的时间表征是必不可少的任务。当前可用的时间表征方法仅支持有限的频谱带宽，而没有有关激光脉冲的载波包络相位（CEP）的信息，或者在真空环境中需要复杂的设备。在这里，我们证明了可以在气态介质或空气中使用子周期隧穿电离直接采样随时间变化的任意激光场。子周期电离被用作直接对激光场进行采样的快速时间门。这种独特的方法可以对环境空气中的宽光谱范围内的激光场（包括其CEP）进行完整的时间表征，从而为精确测量激光场提供了一种通用工具。