A THz driven split-ring resonator based ultrafast relativistic electron streak camera

The use of sub-wavelength metal structures to locally enhance high frequency electromagnetic fields, generally known as plasmonics, enables breakthrough opportunities across diverse fields of research such as nonlinear optics, biosensing, photovoltaics and others. Here we study the application of sub-wavelength metallic resonators tuned in the THz frequency range for manipulation and diagnostics of relativistic electron beams. In this work, we report on the use of a double-sided split-ring structure driven by a near single cycle THz field generated by optical rectification to impart a time-dependent angular deviation (streak) on a 4.5 MeV electron beam. Electrons passing through the small gap reveal field enhancement factors larger than 10, in good agreement with finite difference time domain simulations. This work paves the way for further application of high frequency metallic structures in compact particle accelerators such as for THz-based relativistic electron streaking at fs and sub-fs temporal resolution.