New Perspectives on Electro-Optic Electron Beam Diagnostics at Accelerators

Abstract: Electro-optic detection of the electric field carried by relativistic electron beams is important for electron beam diagnostics at state-of-the art linear electron accelerators, X-ray free electron lasers and synchrotrons.

The presentation discusses the design, fabrication and validation of a thin-film lithium niobate on insulator electro-optic time-domain terahertz (THz) frequency electric field sensor. Thin-film lithium niobate offers unprecedented properties for the electro-optic detection of THz wave radiation pulses and transient electric fields because of the large electro-optic coefficient of the material, engineering of the velocity matching of the THz wave and optical wave and much reduced detector size.

The proof-of-concept device is realized using thin-film lithium niobate optical waveguides forming a Mach–Zehnder interferometer with interferometer arms electrically poled in opposite directions. THz waves are coupled to the fully dielectric device from free space. Microfabricated THz-bandwidth low-loss photonic waveguides, electrically poled lithium niobate and fiber optics result in high-level integration of functionalities currently supported by bulk optical components.

Experimentally validated THz frequency electric field sensor performance will be discussed. Successful proof-of-concepts on time-resolved detection of coherent synchrotron radiation, detection of coherent transition radiation and monitoring of the electron beam arrival with sub-picosecond time resolution using the fiber-coupled photonic integrated electric field sensor will be presented.

Visitors: Those from outside Argonne who wish to attend in person must contact accelerator@​anl.​gov to arrange a gate pass.