Demonstration of acceleration of relativistic electrons at a dielectric microstructure using femtosecond laser pulses.

Acceleration of electrons using laser-driven dielectric microstructures is a promising technology for the miniaturization of particle accelerators. Achieving the desired GV m accelerating gradients is possible only with laser pulse durations shorter than ∼1  ps. In this Letter, we present, to the best of our knowledge, the first demonstration of acceleration of relativistic electrons at a dielectric microstructure driven by femtosecond duration laser pulses.

High-harmonic inverse-free-electron-laser interaction at 800 nm.

We present the first direct observation of a higher-order inverse-free-electron-laser (IFEL) interaction. Interaction at the fourth, fifth, and sixth harmonics is observed from an IFEL operating at 800 nm. The harmonic spacing, relative harmonic strength, and transverse beam overlap of the interaction are all in good agreement with tracking simulations.