Dual-gratings with a Bragg reflector for dielectric laser-driven accelerators

Abstract

The acceleration of a beam of electrons has been observed in a dielectric laser-driven accelerator (DLA) with a gradient of 300 MV/m. It opens the way to building a particle accelerator "on a chip" much more cheaply than a conventional one. This paper investigates numerically an efficient dielectric laser-driven accelerating structure, based on dual-gratings with a Bragg reflector. The design of the structure boosts the accelerating field in the channel, thereby increasing the accelerating gradient by more than 70% compared to bare dual-gratings, from analytical calculations. This is supported by two-dimensional (2D) particle-in-cell simulations, where a 50 MeV electron bunch is loaded into an optimized 100-period structure to interact with a 100 fs pulsed laser having a peak field of 2 GV/m. It demonstrates a loaded accelerating gradient of 1.48 ± 0.10 GV/m, which is (85 ± 26)% higher than that of bare dual-gratings. In addition, studies of the diffraction effect show that the optimized structure should be fabricated with a vertical size of J/ ≥ 0.20 in order to generate an acceptable accelerating performance.

On-Chip Laser-Power Delivery System for Dielectric Laser Accelerators

“…For the parameters discussed, the optimal Q-factors were shown to be around 150. Previous work on optimizing DLA structures for high acceleration gradient has shown that periodic dielectric mirrors may be useful in raising quality factors and field enhancement in DLA structures [39][40][41][42]. However, achieving DLA structures with these Q-factors may be difficult with current fabrication tolerances.…”

Resonant phase matching by oblique illumination of a dielectric laser accelerator

“…In this paper, we demonstrate the flexibility for double grating DLA structures [19,20] to be driven using a laser system of wavelength shorter than the structure periodicity. If illuminated at normal incidence, the phase velocity FIG.…”

Optical design for increased interaction length in a high gradient dielectric laser accelerator

“…Towards this end, researchers have design, built, and power-tested a host of innovative photonic structures, demonstrating synchronous laser-electron interaction with fields up to 1.8 GV/m for relativistic electrons [2] and up to 370 MV/m for subrelativistic electrons [3]. Future structure proposals intend to improve field symmetry, damage handling, staging, diagnostics and more [4,5,6] But so far these devices have been operated in a 'test' configuration in which the drive laser propagates transversely to the electron beam, limiting the interaction region to the laser pulseduration. Since the dielectric lase accelerator (DLA) achieves high gradients by using short pulse lengths to avoid material damage, this necessarily limits the particle-wave interaction to a few microns (or limits the gradient [7]).…”