Electron Modulation and Ultrafast Near-Field Imaging with Vectorial Laser Fields

Controlled interaction of laser light with electron beams is fundamental for ultrafast electron microscopy and electron-based quantum optics, yet their direct coupling is forbidden in free space. Here, we use longitudinally polarized light on a thin membrane and show that the emerging focal fields can modulate the electron beam in a direct, coherent, and linear way, without the need for nanostructured materials or slanted interaction geometries. Also, we use vectorial polarizations to excite and probe three-dimensional nanophotonic near fields in metallic mesocrystals by coherent electron energy gain and loss. We find that longitudinal electric fields excite axial near fields in a direct way, while longitudinal magnetic fields excite oscillating ring currents via azimuthal electric fields. These possibilities enable the tilt-free, collinear generation of attosecond electron pulses or free-electron qubits and provide novel imaging modes in ultrafast electron microscopy and metamaterial tomography.