Energy efficiency studies for dual-grating dielectric laser-driven accelerators

Dielectric laser-driven accelerators (DLAs) can provide high accelerating gradients in the GV/m range due to their having higher breakdown thresholds than metals, which opens the way for the miniaturization of the next generation of particle accelerator facilities. Two kinds of scheme, the addition of a Bragg reflector and the use of pulse-front-tilted (PFT) laser illumination, have been studied separately to improve the energy efficiency for dual-grating DLAs. The Bragg reflector enhances the accelerating gradient of the structure, while the PFT increases the effective interaction length. In this paper, we investigate numerically the advantages of using the two schemes in conjunction. Our calculations show that, for a 100-period structure with a period of 2 μm, such a design effectively increases the energy gain by more than 100 % when compared to employing the Bragg reflector with a normal laser, and by about 50 % when using standard structures with a PFT laser. A total energy gain of as much as 2.6 MeV can be obtained for a PFT laser beam when illuminating a 2000-period dual-grating structure with a Bragg reflector.