Speaker
Description
We present a Dielectric Laser Accelerator concept for achieving tunable interactions with electron beams using silicon photonic integrated circuits to program laser phase fronts. Our photonic circuit is an 8x8 binary tree mesh of Mach-Zehnder Interferometers (MZIs), enabling routing, splitting, and recombination of light via adjustable thermal phase shifters. We couple 2.2 um, 330 fs FWHM laser pulses into eight single-mode waveguides (each with estimated peak fields of 350 MV/m) via a large, high-efficiency (~73%) Three-Wave Interaction Grating (TWIG) coupler. With our circuit architecture, we transform the input beam, with an arbitrary phase front, by aligning the phase in each waveguide channel using TWIG taps, to create a desired wave front incident on an integrated DLA. When illuminated with laser pulses, the DLA generates strong evanescent fields phase-matched to ~40 keV electrons traveling ~100 nm above the silicon surface, allowing gradients up to 75 MeV/m and energy gains on the order of 600 eV across a 128-period structure (0.81 um periodicity). DLAs have been demonstrated as a tool for acceleration, deflection, bunching, and focusing of electron beams, and engineering the incident phase front allows for switching between different interaction modes—unlocking new functionality for controlling electron beam dynamics at optical wavelength scales and kHz frequencies.
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