Femtosecond electron pulse gating using surface plasmons

We present a theoretical investigation of a novel all-optical method for electron beam gating via ponderomotive surface plasmon (SP) interaction. Using femtosecond optical pulses, large electric field gradient SP waves are launched on the surface of a metal film and selectively gate an external electron beam. It is shown that this method can generate electron pulses having similar durations as the laser pulse. The ultrashort electron packets are highly directional and examination of their spatial distribution reveals a large degree of spatial microbunching. Angle-resolved energy spectra of the electrons reveal that their final velocities are highly correlated with exit angle. Furthermore, it is demonstrated that the SP gating technique can be utilized for temporal characterization of ultrashort electron pulses with durations < 100 fs. (c) 2006 Optical Society of America