Merging advanced photonics with ultrafast electron microscopy

Ultrafast electron microscopy provides unique access to dynamics in heterogeneous nanomaterials by implementing laser-pump electron-probe spectroscopy, diffraction, and imaging. In particular, tailored optical interactions promise the coherent control of free electrons and material excitations. Here, I will discuss new opportunities in Ultrafast Transmission Electron Microscopy (UTEM) featuring coherent electron pulses. Optical phase modulation of nanometer-focussed electron beams enables mode-resolved analysis of plasmonic nanocavities, and consecutive mixing with a phase-locked reference gives access to attosecond field-driven dynamics in condensed matter systems. Furthermore, by employing high-Q integrated photonic microresonators, electron-photon coupling is realized down to the single particle level. This enables flexible and highly efficient electron beam structuring, e.g., at the driving optical frequency or deep sub-harmonics using optical beat notes or soliton pulses.