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Demonstration of electron acceleration by an optical evanescent wave at a flat dielectric-vacuum interface published in Optics Express

We could theoretically and experimentally demonstrate an inelastic interaction between free electrons and an optical evanescent wave excited by total internal reflection at the planar interface between high-refractive index materials (silicon, germanium) and vacuum. This effect is interesting for both electron acceleration by optical near-fields and manipulation with energy states of free electrons by laser light. We showed that even without nanostructuring of the dielectric surface, a similar energy modulation can be obtained as in the case of dielectric laser accelerators (DLAs), where nanogratings are used to create an evanescent field synchronous with electrons propagating along the grating surface. The image shows the electric field (z-component) of a plane wave incident to the planar interface between a dielectric (bottom) and vacuum (top). An evanescent wave with phase velocity along the surface synchronous to the electron propagation velocity is generated via total internal reflection. The results of this work where just published in Optics Express.