Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstrasse 1, 91058 Erlangen, Germany.
Department of Electrical Engineering, Stanford University, Stanford, California 94305, USA.
Nat Commun. 2017 Jan 25;8:14342. doi: 10.1038/ncomms14342.
The temporal resolution of ultrafast electron diffraction and microscopy experiments is currently limited by the available experimental techniques for the generation and characterization of electron bunches with single femtosecond or attosecond durations. Here, we present proof of principle experiments of an optical gating concept for free electrons via direct time-domain visualization of the sub-optical cycle energy and transverse momentum structure imprinted on the electron beam. We demonstrate a temporal resolution of 1.2±0.3 fs. The scheme is based on the synchronous interaction between electrons and the near-field mode of a dielectric nano-grating excited by a femtosecond laser pulse with an optical period duration of 6.5 fs. The sub-optical cycle resolution demonstrated here is promising for use in laser-driven streak cameras for attosecond temporal characterization of bunched particle beams as well as time-resolved experiments with free-electron beams.
超快电子衍射和显微镜实验的时间分辨率目前受到用于产生和表征具有单飞秒或阿秒持续时间的电子束的现有实验技术的限制。在这里，我们通过直接时域可视化在电子束上印记的亚光周期能量和横向动量结构，展示了一种通过光学门控自由电子的原理验证实验。我们证明了 1.2±0.3fs 的时间分辨率。该方案基于电子与由飞秒激光脉冲激发的介电纳米光栅的近场模式之间的同步相互作用，该激光脉冲的光周期持续时间为 6.5fs。这里演示的亚光周期分辨率有望用于激光驱动的条纹相机，用于对聚束粒子束进行阿秒时间特性描述以及对自由电子束进行时间分辨实验。
