Fig. 1. All-optical electron beam control in a transmission electron microscope.

(A) Experimental setup and pulse compression concept. A photoemission laser (green) creates short electron pulses (blue) that intersect with the electric or magnetic anti-nodes of a metal waveguide (orange) under terahertz illumination (violet). A pump laser or secondary terahertz beam (red) excites a material and pump-probe, or streaking images are measured on a screen (green). Inset, phase space diagram of terahertz compression in the time-energy domain. If there are no space charge effects (23) and all forces are sufficiently linear in time (25), the initial electron pules (red) become as much shorter in time as they broaden in the energy domain (blue). (B) Generation of electric and magnetic anti-nodes by reflection of terahertz pulses at a displaced waveguide end. The purely electric (red) and purely magnetic (blue) anti-nodes are ideal for pulse compression or streaking of electron beams at positions ① or ②, respectively. (C) Simulated longitudinal electric fields inside the waveguide at ideal time delays for compression (top) and streaking (bottom). (D) Simulated in-plane magnetic fields at ideal time delays for compression (left) and streaking (right). The circle depicts the subwavelength entrance and exit holes for the electron beam.