Electron modulation and ultrafast near-field imaging with vectorial laser fields

TL;DR

This paper demonstrates how vectorial laser fields can coherently modulate electron beams and image near-fields in nanophotonics, enabling new ultrafast electron microscopy and quantum optics techniques.

Contribution

It introduces a method using longitudinally polarized light at a membrane to directly and linearly modulate electron beams without nanostructures or slanted geometries.

Findings

Longitudinal electric fields excite axial near-fields in a direct way.

Longitudinal magnetic fields excite ring currents via azimuthal electric fields.

Enables tilt-free, collinear generation of attosecond electron pulses.

Abstract

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 at 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 tilt-free, collinear generation of attosecond electron pulses or free-electron qubits and provide novel imaging modes in ultrafast electron microscopy and metamaterial tomography.